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DIVERSITY OF ANGIOSPERM LEAF MEGAFOSSILS FROM THE DAKOTA FORMATION (CENOMANIAN, CRETACEOUS), NORTH WESTERN INTERIOR, USA

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DIVERSITY OF ANGIOSPERM LEAF MEGAFOSSILS FROM THE DAKOTA FORMATION (CENOMANIAN, CRETACEOUS), NORTH WESTERN INTERIOR, USA
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2008

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Acute angles ( jstor )
Angiosperms ( jstor )
Fossils ( jstor )
Holotypes ( jstor )
Leaf blade ( jstor )
Leaves ( jstor )
Paratypes ( jstor )
Petioles ( jstor )
Ranches ( jstor )
Species ( jstor )
Florida Museum of Natural History ( local )

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DIVERSITY OF ANGIOSPERM LEAF MEGAFOSSILS FROM THE DAKOTA FORMATION (CENOMANIAN, CRETACEOUS), NORTH WESTERN INTERIOR, USA By HONGSHAN WANG A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2002

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To Meijie and Yuchen

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iii ACKNOWLEDGMENTS I would like to thank the members of my committee, Drs. Walter Judd, Steven Manchester, Ellen Martin, Neil Opdyke, and An thony Randazzo for the interest they have shown in my academic progress and the time that they have spent reviewing this thesis. I thank Dr. David Dilcher, my major supervisor and committee chair, for his continuous encouragement, advice, and support since I first met him in 1995. I thank Professor Guanxiu Yang for encouraging me to pursue a Ph.D. degree in the United States. I thank Dr. Steven R. Manchester for his invalu able discussions and sharing of the lab equipment. I thank Mr. Terry Lott for his assistance in the lab, Dr. David M. Jarzen for his help in the paleobotany collection area. I thank Dr. Scott Wing and Mrs. Amanda Ash (National Museum of Natural History) for access to Lesquereux’s type and other Dakota Formation collections. I thank Carlos Jaramillo for his friendship, useful discussion on the project, and help on computer applications needed in my research. I extend the warmest regards to my fellow graduate students and post-docs, Richard Barclay, Victor Call, Judy Chen, Sarah Corbett, Shusheng Hu, Elizabeth Kowalski, Margaret Landis, Amy McClai n, Mihai Popa, Mike Mueller, Yongdong Wang, Mike Wieman, and Bainian Sun for brightening my years of stay in the paleobotany lab at the Florida Museum of Natural History and in Gainesville, helpfully discussing on my research, and making the paleobotany lab a fun place to work in. I would also like to acknowledge the Department of Geological Sciences, the Graduate Student Council of the Student Government, the College of Liberal Arts and

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iv Sciences, and the Graduate School at the University of Florida for travel support to several conferences to present my research results. I thank the Florida Museum of Natural History for Jerry Britt Award, which par tially supported my field trip to Iowa; the Geological Society of America for partial support of this research, and travel support to GSA meetings; and the Botanical Society of Am erica (Paleobotanical section) for travel support to the Sixth Conference of International Organization of Paleobotany. I thank those numerous people who have helped in the collection of the Dakota Formation specimens since the 1880s. I would like to extend my thanks to the Division of Housing, University of Florida and Drs. Pam Soltis and Douglas Soltis of the Molecular Lab at the Florida Museum of Natural History for financial support for the last four semesters, which is critical to the completion of this dissertation.

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v TABLE OF CONTENTS page ACKNOWLEDGMENTS.................................................................................................iii ABSTRACT......................................................................................................................v ii CHAPTER 1 INTRODUCTION AND BACKGROUND STUDY......................................................1 Introduction................................................................................................................... ..1 Background Study...........................................................................................................3 Paleogeography........................................................................................................3 Stratigraphy..............................................................................................................4 Dakota Formation in Iowa and Nebraska..........................................................5 Dakota Formation in southwestern Minnesota................................................10 Dakota Formation in Kansas............................................................................12 Angiosperm Paleobotany.......................................................................................14 Introduction......................................................................................................14 Background Study............................................................................................16 2 MATERIALS AND METHODS...................................................................................25 3 SYSTEMATICS............................................................................................................29 Floristic Composition....................................................................................................29 Braun’s Ranch Locality, Kansas............................................................................29 Hoisington III Locality, Kansas.............................................................................31 Springfield and Pleasant Dale Localities, Nebraska..............................................33 Courtland I Locality, Minnesota............................................................................34 Systematics...................................................................................................................3 6 Braun’s Ranch Locality, Kansas............................................................................36 Hoisington III Locality, Kansas.............................................................................82 Springfield and Pleasant Dale Localities, Nebraska............................................129 Courtland I Locality, Minnesota..........................................................................152 Diversity Analysis.......................................................................................................202 Introduction..........................................................................................................202 Diversity Analysis of the Dakota Flora................................................................204 Overall Diversity of the Dakota Flora...........................................................204 Comparisons Among Localities.....................................................................206 Diversity Within Individual Localities..........................................................209 Effects on the Diversity Pattern of the Dakota Flora.....................................209

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vi Taphonomic Effects on the Diversity of Angiosperm Leaf Megafossils ......210 Conclusions, Problems, and Perspectives............................................................213 4 PALEOCLIMATE IMPLICATIONS..........................................................................354 Background Study....................................................................................................... 354 Paleoclimatic Implications from Angiosperm Leaf Megafossils................................ 356 Leaf Margin Analysis........................................................................................... 356 Hydathodes........................................................................................................... 356 Leaf Morphology ................................................................................................. 358 Conclusions and Perspectives..................................................................................... 359 5 COMPARISON WITH THE POTOMAC GROUP OF THE EASTERN UNITED STATES ......................................................................................................................360 Background Study....................................................................................................... 360 Comparison Between the Dakota Fl ora and the Potomac Flora................................. 361 Zone I ................................................................................................................... 361 Zone II-B.............................................................................................................. 362 Subzone II-C and Zone III ................................................................................... 365 Conclusion .................................................................................................................. 365 6 CONCLUSIONS, PROBLEM S, AND PERSPECTIVES...........................................367 Conclusions................................................................................................................. 367 Problems and Perspectives.......................................................................................... 368 APPENDIX A SPECIES DISTRIBUTION OF ANGISOEPRM LEAF MEGAFOSSILS IN THE SIX LOCALITIES OF TH E DAKOTA FORMAION ...............................................371 B INDEX OF ANGIOSPE RM SPECIES FROM THE DAKOTA FORMATION.......374 C EXPLANATION OF DIVERSITY INDICES............................................................378 REFERENCES.379 BIOGRAPHICAL SKETCH ...........................................................................................395

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vii Abstract of Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy DIVERSITY OF ANGIOSPERM LEAF MEGAFOSSILS FROM THE DAKOTA FORMATION (CENOMANIAN, CRETACEOUS), NORTH WESTERN INTERIOR, USA By Hongshan Wang May 2002 Chair: David L. Dilcher Department: Geological Sciences During the mid-Cretaceous (about 100 million years before present), one vegetational transition involved the rise to dominance of angiosperms (flowering plants). By this time, the adaptive radiation of angiosperms had already developed major lineages at the level of order and probably some families. As published by Lesquereux, the Dakota Flora is composed of 437 species of angiosperms. The flora of one locality, Rose Creek I, Nebraska, by Upchurch and Dilcher, suggests that the total angiosperm diversity may be about 20 species. In order to fully understand angiosperm diversity at this time period, the early collections such as those described by Lesquereux needed to be critically revised. The present work is the most comprehensive review of the angiosperms in a broad range of the Dakota Flora undertaken and evaluated systematically using modern methods of foliar architecture.

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viii In this project, about 6,000 specimens from six localities of the Dakota Formation were examined. Eighty-seven angiosperm species of 40 genera were identified from 2,670 identifiable leaf megafossil specimens. Diversity analysis shows that the Hoisington III locality, Kansas, and the Courtland I locality, Minnesota, represent the two most diverse angiosperm leaf assemblages of the Dakota Flora. There are 7 to 27 species from each locality. There is less than 25% species overlap between any two localities. The overall diversity of the Dakota Flora is neither as high as that proposed by Lesquereux (437 species), nor as low as suggested by Lidgard and Crane (20 species). Environments were the major control factors of the diversity at individual localities. A conservative estimate of 150 to 200 angiosperm species is proposed. Morphological characters of angiosperm leaves indicate a warm, wet, mesic paleoclimate with possible seasonality on the eastern margin of the Western Interior Seaway during the midCretaceous.

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CHAPTER 1 INTRODUCTION AND BACKGROUND STUDY Introduction The Dakota Formation yields abundant angiosperm leaf megafossils and these fossils have been studied since the late 19th century (Lesquereux, 1868a, 1868b; Newberry, 1868; Lesquereux, 1872, 1873, 1874, 1876a, 1876b, 1876c, 1878, 1883, 1892; Newberry, 1898; Berry, 1911, 1916, 1920, 1922a, 1922b, 1923). However, because of the lack of a clear understanding of leaf arch itecture and the systematic distribution of leaf architectural features in extant angi osperms (Wolfe, 1973; Dilcher, 1974; Doyle and Hickey, 1976), paleobotanists of the 19th and early 20th century assigned these fossil leaves to modern families and genera (Lesquereux, 1892; Berry, 1920). This results in many misinterpretations of the Cretaceous angiosperm record (Wolfe, 1972, 1973; Dilcher, 1974; Wolfe et al., 1975; Doyle and Hickey, 1976; Upchurch and Dilcher, 1990; Upchurch et al., 1994; Dilcher 2000) and blurred the importance of angiosperm leaf fossils in the study of early angiosperm evolution and diversification. This false modern portrayal of the mid-Cretaceous angiosperm record led many people to think that the angiosperms must have had an extensive pre-Cretaceous diversification. The philosophy of assigning the Cretaceous fossil angiosperm leaves to modern families or even genera has changed since the 1970s (Wolfe, 1972; Dilcher, 1974; Doyle and Hickey, 1976; Hughes, 1976). Dilcher (1974, 2000) proposed that up to 60% of all generic assignment to modern genera in some floras are incorrect. Since then, paleobotanists have applied the new philosophy in the study of the Dakota Flora (Dilcher et al., 1976; Dilcher, 1978,

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2 1979; Retallack and Dilcher, 1981; Schwarzwal der and Dilcher, 1981; Crane and Dilcher, 1984; Dilcher and Crane, 1984a,b; Dilcher, 1986; Dilcher and Farley, 1988; Upchurch and Dilcher, 1990). No modern genera were identified from a locality in Nebraska of the Dakota Formation (Upchurch and Dilcher, 1990; Dilcher 2000). Other than these studies, no research has focused on the diversity of angiosperm leaf megafossils of the entire Dakota Flora. One reason for this is that fossil angiosperm leaves have been considered of minimal use for systematic purposes. If other parts of the ancient plants (such as flowers, fruits, wood etc.) are not preserved (in fact they are very rare) and the only information we have is on leaf megafossils, their importance canÂ’t be neglected. Nevertheless, leaves carry clear implications on directions of morphological and ecological evolution of early angiosperms. They represent the early angiosperm diversification pattern. They indirectly affect the relative advancement and relationships of high-rank angiosperm taxa. They represent the first positive indication that the fossil record can achieve a primary role in the reconstruction of angiosperm phylogeny (Hickey and Doyle, 1977). In this project, about 6,000 specimens from 6 localities of the Dakota Formation were examined (Table 1 and Figure 1). I recognized 7 to 27 species from each locality and 87 species from the Dakota Flora. I compared different localities and examined the relationship between each individual locality and the overall Dakota Flora published and described by Lesquereux (1892). The relationship of early angiosperm diversity between different localities and between individual localities and that of the overall Dakota Flora were analyzed. The following questions are addressed by this research: What was the overall diversity of the Dakota Flora and what was the diversity at each locality? Was there a high diversity of angiosperms that is locality specific or

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3 environmentally specific (Retallack and Dilcher, 1986)? What clades of angiosperms dominate each specific locality and how does the angiosperm diversity compare among different localities? If the within-locality diversity is only about 7 to 27 species, then how does the extant diversity at individual localities relate to the overall Dakota Flora of about 437 species of angiosperms observed and published by Lesquereux (1892)? If specimens from numerous localities (or environments) are collected, will there be 437 species of angiosperms? How is the "anomalous" record (Lidgard and Crane, 1988) of 437 angiosperms recorded by Lesquereux (1892) related to the lower level of angiosperm diversity tabulated by Lidgard and Crane (1988)? Is this "anomaly" the result of misidentification of angiosperm leaf megafossils? How does the diversity of angiosperms from the Dakota Formation relate to paleoclimate, paleoecology (environment)? Background Study Paleogeography During the mid-Cretaceous a vast seaway, the Western Interior Seaway (WIS), occupied the Western Interior of North Amer ica (Figure 2). In the United States, the seaway extended about 1,000 miles from central Utah to Minnesota when the sea level was at its highest position. The seaway existed within an asymmetric foreland basin that was bordered on the west by the Columbian-Se vier orogen and flanking foredeep and on the east by the stable cratonic platform (Figure 2) (Kauffman, 1984). Consequently, processes such as sediment accumulation, subsidence, uplift, and erosion on the eastern side are much less dramatic than those of the foreland basin setting on the western side. Tides on the eastern margin were estimated to be microtidal (less than 1 m) (Kauffman and Ryer, 1980; Ryer and Kauffman, 1980). Cretaceous strata are preserved on both sides of the Western Interior Seaway. The Dakota Formation (see the section “Dakota Formation in Iowa and Nebraska” for explanation) was deposited on the stable eastern margin of the seaway in the United States from late Albian to earliest

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4 Turonian, a time of transgression (Witzke and Ludvigson, 1994) and regression (Kauffman, 1977) of the Western Interior Seaway during the Cretaceous. The Dakota Formation is well known for its collections of angiosperm megafossils. The Dakota Formation holds important information on unique depositional settings (Setterholm, 1994; Witzke and Ludvigson, 1994) and yields abundant angiosperm leaf megafossils that provide important information on the early evolution of angiosperms (Upchurch and Dilcher, 1990). The lithology varies in diffe rent areas but is dominated by sandstone, mudstone, and shale with a smaller amount of siltstone or lignite. The source of the sediments is primarily from the deep weathering of the Precambrian metamorphic and igneous rocks to the east or northeast. The sedimentary environments are nonmarine to marginal marine with marine influence increasing up section. Recently, collections of angiosperm leaf megafossils from the Dakota Formation have been made by David Dilcher in the Florida Museum of Natural History (Table 1). Before the formal systematic treatments of these angiosperm fossils, it is important to have a good understanding of the sedimentary geology of the Dakota Formation that yields these fossils. Because all of the angiosperm leaf megafossils are collected from the Dakota Formation, the following survey of previous works concerning the sedimentary geology focuses only on this Formation. Stratigraphy The historic type area of the Dakota Formation is along the Missouri and Big Sioux River Valleys near the Nebraska and Iowa border (Figure 1). It was first described by Meek and Hayden (1858) near Dakota City in northeastern Nebraska. Since then, different terms, such as “Dakota Sandstone”, “Dakota Group”, “Dakota Quartzite”, “Dakota Conglomerate”, and “Dakota Formation” have been used by various authors at

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5 various times to classify the Cretaceous Strata in Arizona, Colorado, Iowa, Kansas, Minnesota, North Dakota, Nebraska, New Me xico, Oklahoma, South Dakota, Texas, Uhta, Montana, Manitoba, Saskatchewan, and Alberta (see USGS, 2001 for references and this unit’s name history). Witzke a nd Ludvigson (1994) suggested that “the Dakota Formation should define as a body of rock of eastern provenance, primarily nonmarine fluvial to marginal marine and deltaic deposits, that were deposited during transgressive phases of the Greenhorn marine cyclothem.” They further proposed “the usage of the terms ‘Dakota Group’ and ‘Dakota Sandstone’ in the Rocky Mountain area is strongly discouraged because the Cretaceous sequences along the western margin of the seaway represent western derived sediments that are la rgely unrelated stratigraphically to the type Dakota area.” In this project, I follow their recommendations and use the term “Dakota Formation” to represent the eastern derived nonmarine to marginal marine sedimentary sequences, which were deposited along the eastern margin of the Western Interior Seaway during both transgressive (Witzke and Ludvigson, 1994) and regressive (Kauffman, 1977) phases in Iowa, Nebraska , Minnesota, North Dakota, South Dakota and Kansas. All the angiosperm leaf megafossils included in the analysis are collected from Nebraska, Minnesota, and Kansas excep t a few from Upchurch and Dilcher (1990), which are collected from Colorado. Dakota Formation in Iowa and Nebraska The Dakota Formation in western Iowa and eastern Minnesota has dual significance for Cretaceous studies in the Western Interior. First, this region includes the historic type area of the Dakota Forma tion, and a thorough definition of the type sequence can provide a basis for comparison with other supposed “Dakota” sequences in the Western Interior (Witzke and Ludvigson, 1994). Second, the transition from

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6 nonmarine to marine sediments of the Greenhorn cycle is preserved in the Dakota Graneros sequence in this area, providing a valuable record of sedimentary processes along the stable eastern margin of the Western Interior Seaway (Setterholm, 1994; Witzke and Ludvigson, 1994). The Dakota Forma tion in the type area and across western Iowa is subdivided into two members, Nishnabotany and Woodbury (White, 1870; Munter et al., 1983). The Nishnabotany Member is a sandstone-dominated sequence unconformably overlying an eroded surface of Paleozoic or Precambrian rocks. The Woodbury Member is dominated by shale and mudstone, with secondary sandstone, siltstone, and lignite. The Woodbury oversteps the Nishnabotany edge eastward in northern Iowa to overlie Paleozoic strata and is capped by marine strata of the “Graneros” shale. The age of the Nishnabotany Member is suggested by palynomorphs as late Albian to early Cenomanian and the Cenomanian age of the Woodbury Member is constrained by marine fossils at the top and palynomorphs throughout (Schemel, 1950; Pierce, 1961; Hall, 1963; Austin, 1970; Ravn and Witzke, 1994, 1995). Based on palynostratigraphic, lithostratigraphic, and sedimentologic data, Brenner et al. (2000) divided the Dakota formation into three sedimentary sequences bounded by three unconformities. These three breaks are interpreted as regional unconformities that extend across the eastern margin of the Western Interior Seaway from western Iowa to western Kansas. One important conclusion is the correlation between the nonmarine Nishnabotany Member of he Dakota Formation in western Iowa and northeastern Nebraska and parts of Kiowa-Skull Creek Formation marine transgressive mudrocks in Kansas (Figure 3). This correlation provides an important chronostratigraphic link

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7 between the nonmarine Upper Albian strata of the eastern margin of the Western Interior Seaway and the previously well studied marine parts of the basin (Brenner et al., 2000). Mudstones and shales of the Dakota Formation have a high kaolinite content with a smaller amount of illite (Frye et al., 1964; Parham and Hogberg, 1964; Parham, 1970; Bowe, 1972). Pisolitic kaolinitic claystone from some localities texturally resemble bauxites and the presence of gibbsite and boehmite (Parham, 1970) further suggests bauxitization processes. Silty laminae or other current-formed sedimentary structures are common in the mudstone and shales and some mudstones show pedogenic features to varying degrees, particularly in the Nishnabotany and Woodbury members. Such mudstones are commonly mottled or rooted and they disrupt or obliterate primary sedimentary structures. Well developed paleosols from the reddish-mottled siltstones and mudstones form the middle part of the Dakota Formation in eastern Nebraska were described by Joechel (1987, 1991). Sandstones of the Dakota Formation of the type area consist of angular to subrounded sand and silt, with coarse grains varying from subrounded to rounded. Feldspar grains are present in many fine-to-medium grained sandstones and muscovite grains are common in fine-grained sandstones and siltstones. Metamorphic rock fragments (quartz-mica schist grains) are present in some sandstones (Witzke and Ludvigson, 1996). Silicified debris of bryoz oans, trilobites, brachiopods, crinoids, fusulinids, and rogose and tabulate corals also common in the chert clasts (Witzke and Ludvigson, 1982). Ludvigson et al. (1987) noti ced that unstable grains (metamorphic rocks fragments and feldspar grains) increase upward in the Dakota Formation. Different types of cements (siderite, pyrite, ferric oxide, and calcite) are recognized in the Dakota

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8 sandstones. Most of the sandstones ar e poorly indurated (Ludvigson et al., 1987). Siderite cements are common in the Nishnabotany Member while calcite cements are most common in upper Woodbury siltstones. Brenner et al. (1981) suggested that methanic diagenetic environments were followed by sulfide environments because the siderite cements preceded pyrite in the Dakota Formation. It is further interpreted by Ludvigson et al. (1987) that the Dakota represents early diagenesis in nonmarine porefluids, with later stage diagenesis influenced by marine derived fluids. According to the current-formed sedimentary structures and paleovalleys in the Dakota Formation from the type area, the source area of sediments is to the east and northeast (Witzke and Ludvigson, 1994). Deep weathering of the Precambrian (Proterozoic igneous rocks and Archean metamorphic rocks) terrains in Minnesota and Wisconsin provided most of the sediments for the Dakota Formation, with the Paleozoic chert-bearing carbonate strata to be considered as a secondary source. Deep weathering and chemical alteration of Precambrian base rocks produced regoliths that are rich in quartz and kaolinite and are relatively depleted in less stable minerals such as feldspars. The subsequent erosion of the kaolinite-rich regolith provided angular quartz and kaolinite sediments to the Dakota depositional systems. Progressive erosional removal of kaolinitic regoliths in the source areas result in the upward increase in feldspar and metamorphic rock fragments observed in the Dakota sequence of northeast Iowa. Although erosion of the Paleozoic strata provided chert grains to the Dakota stream systems, Witzke and Ludvigson (1994) suggested that the Paleozoic terrains mainly served as surfaces of transport for a sediment load primarily from Precambrian sources

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9 and most of the sediments of the Dakota Formation are interpreted as first cycle siliciclastic detritus. The sedimentary environment of the lower Nishnabotany Member is interpreted as braided fluvial systems of relative low si nuosity, probably trending into coarse-grained meandering-belt systems distally (Karl, 1976; Whitley, 1980; Whitley and Brenner, 1981; Witzke, 1983). The upper Nishnabotany Member is interpreted as proximal meandering belt fluvial systems (Witzke and Ludvigson, 1982). Because of a general decrease in stream competency, paleosols developed locally in flood basin and overbank mudstones. The Cenomanian base level arising resulted in marine transgression in the nearby seaway. The sedimentary environments of lower Woodbury Member are interpreted as overbank and flood basin dominated with lignites forming in oxbow and flood plain swamps (Witzke and Ludvigson, 1994, 1996). Marginal marine environments first appeared in the middle part of the Woodbury Member, which indicates the initial marine transgression into the area during the mid-Cenomanian. Both the middle and upper parts of the Woodbury Member show evidence of marginal marine and nonmarine environments (Witzke and Ludvigson, 1994, 1996). Aggradation of coarse-grained braided fluvial sediments, formerly restrict ed to areas of western Iowa and eastern Nebraska during the Albian, was pushed eas tward during the Cenomanian. During this time, more distal fluvial sediments in western Iowa and adjacent Nebraska were marked by fine-grained meander belt system (Witzke et al., 1983). This interval is interpreted as a mosaic of nearshore, fluvial and delta distributary channels. Nonmarine sediments became less common upward through the middle and upper Woodbury and the nearshore

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10 and deltaic facies are displaced progressive ly by offshore and pelagic carbonate facies, which were assigned to the “Graneros Shale” (Witzke and Ludvigson, 1996). In general, the Dakota Formation (late Albian to late Cenomanian) in the type area is dominated by sandstone, mudstone and shale. The provenance for most of the Dakota sediments is to the east or northeast from deeply weathered Precambrian rocks, which provided both quartz grains and clay minerals. The lower Dakota sediments represent a shift from coarse-grained braided-fluvial to proximal meandering belt environments. The upper Dakota sediments represent an upward shift from fluvial channel and flood basin meandering belt environments to deltaic and marginal marine environments. During the middle to late Cenomanian, eastward transgression of the Western Interior Seaway displaced the upper Dakota nearshore and deltaic facies by offshore marine shale facies (Witzke and Ludvigson, 1994, 1996). Dakota Formation in southwestern Minnesota In southwestern Minnesota, the sedimentary geology of the Dakota Formation is similar to that of the type area. The Cretaceous strata overlie unconformably on the Precambrian rocks (Setterholm, 1994). Based on subsurface information and previous investigations, Setterholm (1994) established eight informal lithostratigraphic units and one formation for the Cretaceous rocks from this area. Each unit is defined either by a certain rock type or by a combination of rock types. He further interpreted the depositional history of the area based on the rock units and their physical relationships. In ascending order, these lithostratigraphic units are Sandstone, Mudstone, Lower Interbedded Shale, Marlstone, Speckled Shale, Noncalcareous Shale, Siltstone, Upper Interbedded Shale, and Split Rock Formation. Based on lithology and age, Setterholm (1994) suggested that the sandstone unit is similar to the Nishnabotany Member. The

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11 mudstone unit is similar to the Woodbury Member but it is thicker, indicating that this unit was probably deposited when Graneros Shale was deposited in the western part of southwestern Minnesota. The lower Interbedded shale unit, which only occurs in the western part, closely correlates with the Graneros Shale. The outcrop of the Sandstone unit is rare because it is overlain in this area by younger strata (Setterholm, 1994). It can be up to 26 m thick and is quartzose, micaceous, and is locally intercalated with kaolinitic claystone. The rounded to angular quartz grains were interpreted to derive from a pre-Cretaceous saprolith. Its thickness varies according to the paleo-topography of the Pre-Cretaceous surface and lies directly on the weathered Precambrian surface and is overlain either by the Mudstone or the Interbedded Shale unit (Setterholm, 1994). The Mudstone unit, which contains gray and brown mudstone with many thin sandstone beds, is characterized by coarsening-upward subunits. Each subunit starts with clay and fine silt and is toped by thin siderite cemented sandstone. This was interpreted as related to local autocylic processes instead of sea level fluctuations, subsidence or other larger scale events because they correlate only over a short distance (less than 10 km). This unit generally overlies sandstone but may directly overlie the Precambrian rock (Setterholm, 1994). The Lower Interbedded Shale unit, which is dominated by light to dark gray shale with interbeds of siltstone, sandstone and silty shale, is overlain by marine marlstone and underlain by mudstone or Precambrian rocks (Setterholm, 1994). Based on lithologic characteristics, structure, fossils, and physical relationships, Setterholm (1994) interpreted the depositional history of the Cretaceous rocks from

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12 southwestern Minnesota. The earliest Cretaceous rocks were deposited in the low areas fluvial systems on the pre-Cretaceous surface. As the sea transgresses eastward in the late Cenomanian, a transition from nonmarine to marine deposition began. Because of sea level rise, the eastern part of the southwestern Minnesota became the site of mostly deltaic and nearshore environments. The repeated infixing of interdistributary bays of fluvial dominated delta result in the deposition of the coarsening upward, cyclic deposits of the mudstone unit. The west part of the southwestern Minnesota was mainly marine environments (deposition of the lower Interbedded shale unit). The sea level rise was completed in the early Turonian. From late Cenomanian to early Turonian, some high areas, especially the Sioux Ridge, remained as islands. The Split Rock Formation was deposited mainly in embayments of the ridge. Dakota Formation in Kansas In Kansas, the Dakota Formation is defined as nonmarine and littoral clay and sandstone over the Kiowa Formation and below the Graneros Shale, and consists of the Terra Cotta Clay below and Janssen Clay Members above (Plummer and Romary, 1942). The type sections for both members are in cen tral Kansas. Brenner et al. (2000) divided the mid-Cretaceous strata into four lithostratigraphic units. In ascending order, these units are Cheyenne Sandstone, Kiowa Formation (equivalent to Longford member), Dakota Formation (further divided into the lower Terra Cotta Clay member and upper Janssen Clay Member), and Graneros Shale (Figure 3). The Dakota Formation in Kansas unconformably overlies Kiowa Formation and is overlain disconformably by the Graneros Shale. It is separated from the lower Kiowa Formation by an erosional surface (Hamilton, 1994). Clay lithology dominates the Dakota Formation with sandstone rarely exceeding 40% of the formationÂ’s thickness (Bayne et al., 1971). Hamilton (1989, 1994)

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13 interpreted the sandstone of the basal Dakota Formation in Kansas as fluvial deposits within incised valleys based on concave-up erosional bases, abundance of clay pebbles, and the lack of marine fossils or bioturbation. The thickness of the Dakota Formation varies from 200 to 300 feet (Macfarlane, 1990). The temporal interpretation of Brenner et al. (2000) constrained the age of the Dakota Formation in Kansas to latest Late Albian to earliest Early Cenomanian (Figure 3), as compared with previous interpretations by Hamilton (1994) and Scott et al. (1998). Other temporal interpretations of the Dakota Formation in Kansas are by Franks (1975, Albian to Cenomanian age), with the upper part restricted to the Cenomanian (Hattin, 1965; Franks, 1966). Foraminifera from the underlying Kiowa Formation defines its age to be Albian (Loeblich and Tappan, 1961) while palynology study indicates the age to be early late to latest Albian (Ward, 1986). Arenaceous Foraminifera from the overlying Graneros Shale indicate its age to be Cenomanian (Eicher, 1965). Marine invertebrate fossils from the uppermost Dakota Formation were interpreted as middle Cenomanian age (Hattin, 1965, 1967). The absence of Normapolles group pollen (Farley and Dilcher, 1986) from the samples of the Dakota Formation indicates its age to be older than late Cenomanian, the time that is believed to be the first appearance of that Group in North America (Tschudy, 1981). Based on these data, the age of the Dakota Formation in Kansas is probably from late Albian to middle Cenomanian, which straddles the Upper and Lower Cretaceous boundary (Zeller, 1968; Kauffman, 1977). The lower part of the Dakota Formation, the Terra Cotta Clay Member, is characterized by gray claystone and red-mottled massive claystone, siltstone, and sandstone (Plummer and Romary, 1942). Thickness of this member ranges from 45.7 m

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14 to 76.2 m (Franks, 1966). The sandstones in northern Kansas were deposited in low sinuosity bedload streams flowing southwest (K arl, 1976) and fined-grained facies were deposited in flood plains adjacent to these rivers (Franks, 1975). The contact between these two members is placed at the top of a concretionary siderite limonite, or hematite, and/or “quartzite” sandstone that is overlain by a bed of gray, massive clay (Plummer and Romary, 1942). The upper part of Dakota Formation, Janssen Clay Member, is dominated by kaolinitic claystone, siltstone, some shale, and sandstone (Plummer and Romary, 1942). They represent a transitional from nonmarine to marine environments. Sandstone lenses were deposited in meandering streams (Karl, 1976) and the flat-bedded sandstone were deposited in estuaries and deltas, lignites in fresh to brackish water swamps, and ironbearing claystone in brackish and open marine bays (Siemers, 1971). The Graneros Shale was deposited in shallow nearshore (lower part) and offshore marine environments (upper part) (Hattin, 1965). Paleocurrent indicators throughout the Dakota Formation generally trend west to southwest (Franks, 1966; Siemers, 1976) Angiosperm Paleobotany Introduction The mid-Cretaceous was an important period in the evolution of angiosperms. By this time, the angiosperms had began their adaptive radiation, and major lineages at the level of subclass, order and probably some families made their first appearance (Upchurch and Dilcher, 1990). The paleobotanists of the 19th and 20th centuries (Lesquereux, 1868a, 1868b, 1872, 1873, 1874, 1876a, 1876b, 1876c, 1878, 1883, 1892; Berry, 1911, 1916, 1920, 1922a, 1922b; 1923; Newberry, 1868, 1886, 1895, 1898) described many angiosperm leaf megafossils from the Dakota Formation without a clear

PAGE 23

15 understanding of foliar architecture and cuticular anatomy and assigned these fossils to modern angiosperm genera or even species. Hence the "falsely modern aspect" (Wolfe, 1973; Dilcher, 1974; Doyle and Hickey, 1976; Upchurch and Dilcher, 1990) due to "picture matching" (Wolfe, 1973; Dilcher, 1974) of the early angiosperm leaf megafossils from these floras led to numerous misinterpr etations in the understanding of angiosperm evolution (Wolfe, 1973; Dilcher, 1974; Doyle and Hickey, 1976; Upchurch and Dilcher, 1990; Dilcher, 2000). In their compilation of floristic diversity from Late Jurassic to Paleocene, Lidgard and Crane (1988) considered the Dakota Flora to be anomalous and excluded data from the Dakota Flora in their tabulations because of the great diversity of angiosperms (437 species) when compared with other floras (Figure 4). This false modern aspect of the mid-Cretaceous angiosperm record led many people to think that the angiosperms must have an extensive pre-Cretaceous diversification. The philosophy of assigning the Cretaceous fossil angiosperm leaves to modern family or even genera has been changed since the seventies of the last century (Wolfe, 1972; Dilcher, 1974; Doyle and Hickey, 1976; Hughes, 1976). Ba sed on morphological characters, Dilcher (1974, 2000) proposed that up to 60% of all generic assignment to modern genera in some floras are incorrect. Since then, paleobotanists have applied the new philosophy in the study of the Dakota Flora (Dilcher et al., 1976; Dilcher, 1978, 1979; Retallack and Dilcher, 1981a, 1981b; Schwarzwalder and Dilcher, 1981; Crane and Dilcher, 1984; Schwarzwalder, 1986; Upchurch and Dilcher, 1990; Schwarzwalder, 1991; Upchurch et al., 1994) and the validity of not assigning Cretaceous angiosperm species to modern genera has been reiterated (Dilcher, 1979; Retallack and Dilcher, 1981a, b). No modern genera were identified from a locality of Nebraska of the Dakota Formation (Upchurch

PAGE 24

16 and Dilcher, 1990; Upchurch et al., 1994; Dilcher 2000). Despite these works, there is no work focusing on the overall diversity of angiosperm leaf megafossils of the Dakota flora. There is a need to re-examine the floras of the Dakota Formation from different localities in order to (1) understand the diversity of the angiosperms of this critical period; (2) understand the early evolution of angiosperms during the Cretaceous; (3) compare the Dakota Flora with those of the same age from the western margin of Western Interior Seaway; and (4) compare Dakota Flora with other floras from other areas of the world. Also this re-examination could further help us to understand the early angiosperm diversity and the overall diversity pattern of vascular plants. Background Study Angiosperm leaf megafossils are abundant in the Dakota Formation (Lesquereux, 1874, 1876, 1883, 1892; Tester, 1931; Dilcher et al ., 1976; Dilcher, 1978; Retallack and Dilcher, 1981a, 1981b; Basinger and Dilcher, 1984; Crane and Dilcher, 1984; Dilcher, 1984; Dilcher and Crane, 1984a,b; Kovach and Dilcher, 1985, 1986; Retallack and Dilcher, 1986; Kovach, 1987; Kovach and Dilcher, 1988; Upchurch and Dilcher, 1990). Lesquereux (1892) described the fossil plants from the Dakota Formation (Group) and recognized 437 species of angiosperm leaf megafossils, of which 8 are monocotyledons and 429 dicotyledons. He assigned most of the angiosperm leaf megafossils to extant families and genera, as other paleobotanists of his age did, even though these leaves lacked one or more features found in the extant taxa. His collections are focused on the localities from Kansas (Table 2). Approximately 89.6% (328 of 366 species) of LesquereuxÂ’s collections were from Kansas. In comparison, the localities for this project are well distributed in the northwestern Interi or (Table 1 and Figure 1). However, he

PAGE 25

17 recognized that the specimens from different localities generally represented different species. Sometimes all the leaves of a local area belong to one species, while at a short distance away, another group of leaves represents other species, genera, of even families. He recorded in a large number of leaves embedded in concretions. More than three thousand specimens of this kind were collected from that County. The concretionary specimens were found at 12 different localities, in groups covering limited areas, the largest tract being about 90 meters, the others not more than 18 meters in width (Lesquereux, 1892). The specimens of each locality were collected separately and were also identified separately, and each locality was found to be composed of one to three types of angiosperm leaves. Few leaf types were represented in more than two or three localities. Rushforth (1971) studied the Westwater Flora from the Dakota Sandstone Formation near Westwater, Grand County, Utah and recognized fourteen genera including nineteen species, six of which were assigned to angiosperms. Dilcher and Crane (1984a) noted that there are 15 to 20 species of angiosperm leaves from the Dakota Formation at Linnenberger Brothers Ranch locality near Bunker Hill, Russell County, central Kansas (Table 1). Retallack and Dilcher (1981a, 1981b, 1986) stated that the angiosperms were most abundant and diverse in coastal and fluvial depositional environments from their appearance in Early Cretaceous into Late Cretaceous as opposed to gymnosperms and ferns. They also noted that the early angiosperm paleoecology, paleoenvironment and geological age as well as their morphology and systematics are important for a full understanding of early angiosperm diversity.

PAGE 26

18 Upchurch and Dilcher (1990) described 20 species (revised to 22 in this study) of angiosperm leaves from the Rose Creek I locality in Nebraska. This was the first time that angiosperm leaf megafossils from the Dakota Formation were treated systematically using modern methods of foliar architecture and cuticular anatomy. Skog and Dilcher (1994) summarized the percent species from Farley and DilcherÂ’s data (Farley and Dilcher 1986) for the miospores and their data for the megafossils. Their work focused on the lower vascular plant fossils of five localities from the Dakota Formation and recognized 13 species including one lycophyte, one sphenophyte and eleven pterophytes. David Dilcher (Table 1), students and colleagues have made extensive collections of angiosperm leaf megafossils from many localities from Kansas, Nebraska, and Minnesota during the past forty years. This enables the comprehensive survey of Dakota Angiosperms. This research focuses on angiosperm leaf megafossils from five localities of the Dakota Formation.

PAGE 27

19 Table 1. Angiosperm leaf megafossil localities from the Dakota Formation (?Interpretation of sedimentary environments not available.) Locality State Number of specimens collected Number of angiosperm species Suggested sedimentary environments Linnenberger Brothers' Ranch 916 ca.15 Swamp (Farley and Dilcher, 1986) Braun’s Ranch 2500 23 Marsh lakeside (Farley and Dilcher, 1986) Hoisington III KS 1255 27 Fresh water lake or lagoon environment with river influence (Retallack and Dilcher, 1981a, b; Skog and Dilcher, 1992) Courtland I MN 500 23 ? Rose Creek I 1836 22 (Upchurch and Dilcher, 1990) Tidally influenced distributary margin (Farley and Dilcher, 1986) Pleasant Dale 275 12 ? Springfield NB 125 5 ? Total 7407 87 (unique species)

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20 Table 2. Tabulation of Lesquereux’s (1874, 1882, 1892) localities from the Dakota Formation (?-Locality not specified in Lesquereux’s publications.) Locality State Number of species Ellsworth County 136 Fort Harker, Ellsworth County 61 Near Carneico, Ellsworth County 3 Brookville 3 ? 36 Ten miles northeast of Delphos 37 Pine Creek, Cloud County 21 Two and a half miles north of Glasco 8 Two and a half miles south of Glasco 5 Seven miles northeast of Glasco 5 Western Kansas 3 Clay County 5 Salina Station 3 Bluff Creek KS 2 Subtotal number of species from Kansas 328 Decatur 13 Lancaster County 2 Near Lancaster 1 Platte River, Cass County 1 Beatrice, Gage County 1 ? 3 Blackbird Hills 1 Tekamah NE 1 Subtotal number of species from Nebraska 23 Mankato 1 ? 9 Big Cottonwood River near New Ulm MN 1 Subtotal number of species from Minnesota 11 Total number of species from KS, NE, and MN 362 of 437 published by Lesquereux (1892)

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21 Figure 1. Plant megafossil localities and regional outcrop of the Dakota Formation. Map ranges from southern Minnesota (MN) to north central Kansas (KS) along the eastern margin of the Western Interior Seaway in the United States. 1Linnenberger’s Ranch; 2-Braun’s Ranch; 3-Rose Creek I; 4-Courtland I; 5Hoisington III; 6Pleasant Dale; 7-Springfield; ?-Potential locality from Iowa. State boundaries are dashed. Outcrop map based on Witzke and Ludvigson (1996). IL-Illinois; IA-Iowa; KS-Kansa s; MN-Minnesota; NB-Nebraska; MOMissouri; SD-South Dakota; WS-Wisconsin.

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22 Figure 2. Extent of Western Interior Seaway during Late Turonian. Rectangle defines the study area. Paleogeographic map modified from Roberts and Kirschbaum (1995).

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23 Figure 3. Stratigraphic nomenclature chart of the Albian and Cenomanian subdivisions of the Dakota Formation and associated stratigraphic units in Kansas and the “Tri-state area” of eastern Nebraska, western and central Iowa, and eastern South Dakota. Modified from Brenner et al. (2000).

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24 Figure 4. Absolute systematic diversity of tracheophytes. Cycad-cycadophytes; ginkgoginkgophytes. A-diversity curves of tracheophytes. Species richness is summed from 19 Late Jurassic to Paleocene megafossil flora. The Dakota Flora is excluded. B-if Dakota Flora is included with ½ species overlap with other flora, there will be a spike at the Cenomanian (modified after Lidgard and Crane, 1988). ! " # $ ! % " !"#!&'() ! " # * $ ! % " !"#!&'() $%&'!#()

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25 CHAPTER 2 MATERIALS AND METHODS All specimens examined during this research are collected from the Dakota Formation (Figure 2, Table 1) by David Dilcher, his students and colleagues since 1974. Most of the specimens are preserved as impressions. Some specimens from the Courtland I locality, Minnesota and Pleasant Dale locality, Nebraska have very well preserved cuticular materials, but the cuticular characters are not examined in this study due to time limitations. For impression specimens, extreme oblique lighting was applied to highlight the venation pattern. All descriptions of specimens are based on direct observation under dissecting microscope. Enhancement of details is obtained by highcontrast photography with Kodak Technical Pan 2415 film or Ektachrome 160-tungsten slide film with a Nikon 35mm camera and/or by line drawings. All images were scanned with a Nikon LS-1200 Slide Scanner, saved on CDs with an Adapter Easy CD Creator, and processed using Adobe Photoshop 6.0 software. In this project, I follow Upchurch and Dilcher (1990) and StevensÂ’s (2001) classification criteria. Comparisons with other fossil taxa are based primarily on published figures and/or plates, except some of those published by Lesquereux (1892). Comparisons with these taxa are based on direct observations of published type specimens stored at the paleobiology department, the National Museum of Natural History. Comparisons with extant taxa are also based on published images.

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26 Leaf architectural terminology mostly follows Dilcher (1974) with reference to Hickey (1973, 1979), Wolfe et al. (1975), Wolfe and Wehr 1987b, and LAWG-Leaf Architecture Working Group (1999). The following are exceptions: I’ve used “leaf” and/or “leaflet” to describe specimens only if the specimens demonstrate enough features to show leaf organization (i.e., simple or compound). Otherwise I chose to use “lamina” in descriptions. For leaf organization, I follow LAWG’s (1999) terms in descriptions: Simple leafconsisting of a single lamina; trifoliate-a compound leaf with three leaflets; palmately compound-a leaf with separate subunits (leafle ts) attached at the apex of a petiole. Petiolule represents the stalk of a leaflet and sessile means that a leaflet lacks a petiolule (stalk); pinnately compound-a leaf with leaflets arranged along a rachis. Odd-pinnate to represent leaf with a single terminal leaflet and even-pinnate for leaf with two terminal leaflets. In describing palmately compound leaf or palmately lobed leaves, I chose to use medial lobe/leaflet to refer to the middle lobe/leaflet; lateral lobes/leaflets to refer to two outer lobes/leaflets if the leaf is three lobed or compound with three leaflets; inner (or outer) lateral lobes/leaflets are used to represent lateral lobes/leaflets if the leaf is five-lobed or compound with five leaflets. I follow Upchurch and Dilcher (1990) and Upchurch et al. (1994) to use “cf.” to indicate one or a few minor quantitative differences between Dakota and a previously published species. An “aff.” to indicate general similarity between Dakota taxon and a published taxon but with greater morphologic differences, usually in one or more qualitative characters used to diagnose the taxon. The following abbreviations are used: L/W to represent the ratio of leaf or lamina length to maximum width. When describing the angle of origin of tertiary veins, I use A, R, and O to represent acute, right, and obtuse angles respectively (Dilcher, 1974). For example, AO represents tertiary veins originated from the exmedial (lower or basal) side of the secondary veins at acute angles and obtuse angles from the admedial (upper or apical) side of secondary veins (Dilcher, 1974). “Assemblage” is used in floral analysis to represent floral composition for each locality and Dakota Flora to represent all the plants from the Dakota Formation. All specimens examined in this study are deposited in the Paleobotanical collection of the Florida Museum of Natural History at the University of Florida and are given the prefix UF15713 (Rose Creek I locality, Nebraska), UF18038 (Pleasant Dale, Nebraska), UF18047 (Springfield, Nebraska), UF15709 (Braun Brothers Ranch, Kansas),

PAGE 35

27 UF15706 (Hoisington III, Kansas), UF18267 (Courtland I, Minnesota). The following are the detailed geographic information about each locality and interpretations of age and sedimentary environment for some localities: UF 15709, Braun’s Ranch, Cloud County, Kansas . Description: Near Delphos, Kansas. Small claypit about 2 miles southwest of Braun’s Ranch House. About 0.5 miles west of 200th Road on Cloud Road. Coordinates: SW , SE , sec. 32, T8S, R2W, Lamar, KS Quadrangle 7.5’ series. Latitude/Longitude: 40 03.01’N 97 10.12’W. Age: “Middle” Dakota Formation based on sedimentology and general position in the Dakota outcrop belt, below Rose Creek I and Linnenberger’ Ranch localities (Retallack and Dilcher, 1981). Sedimentary environment: fresh water lake on an alluvial floodplain (Retallack and Dilcher, 1981; Farley and Dilcher, 1986). UF 15706, Hoisington III, Barton County, Kansas . Description: Claystone overlying interbeded sandstone and shales that were exposed at the south end of the north claypit, which is two miles south of Hoisington, Kansas on state route 121. Coordinates: Center E1/2, sec. 20, T 18S, R13W, Great Bend NE, Barton Co., KS Quadrangle 1959, photo revised 1983, 7.5’ series. Latitude/Longitude: 38 28.31’N 98 46.918’W. Age: Early Cenomanian (Farley and Dilcher, 1986). Sedimentary environment: fresh water lake or brackish water lagoon environment with river influence (Retallack and Dilcher, 1981; Skog et al., 1992a; Skog et al.1992b; Skog and Dilcher, 1994). UF 15713, Rose Creek I, Jefferson County, Nebr aska. Description: Six miles south of Fairbury, 50-100 m east of State Route 15. Coordinates: SW SE , sec. 14, T1N, R2E, Fairbury SW, KS Quadrangle 7.5’ series. Latitude/Longitude: 40 03.01’N 97 10.12’W. Leaf megafossils collected from the upper half of the Janssen Clay Member, on the west-facing wall of the pit. Age: early to middle Cenomanian dated by palynology (Farley and Dilcher, 1986), macroinvertebrates (Hattin, 1967; Cobban and Merewether, 1983), and lighostratigraphic position (Upchurch and Dilcher, 1990). Sedimentary environment: a coastal swamp with periods of inundation with brackish water and tidal influences (Farley and Dilcher, 1986; Upchurch and Dilcher, 1990). UF18038, Pleasant Dale, Seward County, Nebraska . Description: Clay pit west of Pleasant Dale, a small town west of Lincoln, on State Highway 103, south of US highway 6. Coordinates: Pleasant Dale, NE Quadrangle, 7.5’ series. Latitude/Longitude: 40.79180 N-96.93272 W. UF18047, Springfield, Sarpy County, Nebraska. Description: Omaha Brick Works. Past the town of Springville, east to gravel road, south to private road and then east to the “pit”. Omaha Brick Works, 72nd and Q Street, Ralston, NE 69051. Coordinates: SW SE NW sec. 30, T13N, R12E, Cedar Creek, NE Quadrangle 7.5’ series. Latitude/Longitude: 41 04”N 96 07”W GNIS.

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28 UF18267, Courtland I, Nicollet County, Minnesota. Coordinates: T109N, R29W. Latitude/Longitude: 44 16’29”N 94 23’13”W GPS.

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29 CHAPTER 3 SYSTEMATICS Floristic Composition The following list contains all the leaf taxa described in this project. I follow the classification criteria of Upchurch and D ilcher (1990) and Stevens (2001). If enough information is available, these leaf megafossils are assigned to modern order. Few fossils are assigned to modern subordinal taxa. Most fossils are designated either with cf. or aff. to indicate their relationships with the most similar extant families. The list contains four sections for BraunÂ’s Ranch, Hoisington III, Springfield and Pleasant Dale, and Courtland I localities. For a list of species arranged in alphabetical order and the number of specimens examined for each species, please see Appendix A. BraunÂ’s Ranch Locality, Kansas MAGNOLIIDS Order LAURALES Genus Wolfiophyllum Wang gen. nov. Wolfiophyllum heigii Wang sp. nov. (Figure 17, 7-9; Figure 17, 11-12; Figure 19,7-8) Wolfiophyllum daphneoides (Lesquereux) Wang comb. nov. (Figure 26, 4-6) Genus Crassidenticulum Upchurch and Dilcher 1990 Crassidenticulum decurrens Upchurch and Dilcher 1990 (Figure 25, 1-10; Figure 26, 1-3) Crassidenticulum trilobus Wang sp. nov. (Figure 21, 1-8; Figure 22, 1-6; Figure 23, 6-8) Crassidenticulum landisae Wang sp. nov. (Figure 27, 1-9; Figure 28, 1-5) Genus Landonia Upchurch and Dilcher 1990 Landonia mullerii Wang sp. nov. (Figure 23, 5) Genus Yangia Wang gen. nov. Yangia glandifolium Wang sp. nov.

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30 (Figure 29, 1-4; Figure 30, 7-8) Genus Rogersia Fontaine 1889 Rogersia parlatorii Fontaine 1889 (Figure 17, 1-6; Figure 17, 10; Figure 18, 1-11; Figure 23, 1) Rogersia lottii Wang sp. nov. (Figure 19,1-3) EUDICOT Order PROTEALES Dumort. aff. family Platanaceae Genus Credneria Zenker emend. Schwarzwalder and Dilcher 1986 Credneria quadratus (Lesquereux) Wang comb. nov. (Figure 24, 1-3) Genus Dischidus Schwarzwalder and Dilcher 1986 Dischidus quinquelobus Wang sp. nov. (Figure 20, 1-4) Genus Eoplatanus Schwarzwalder and Dilcher 1986 Eoplatanus serrata Schwarzwalder and Dilcher 1986 (Figure 13, 1-10; Figure 14, 1-7; Figure 15, 1; Figure 15, 2, Figure 15, 6; Figure 16, 1-15) Genus Aspidiophyllum Schwarzwalder and Dilcher 1986 Aspidiophyllum denticulatus Wang sp. nov. (Figure 15, 3-5) CORE EUDICOTS Order SAXIFRAGALES Dumort. Genus Trochodendroides Berry 1922 Trochodendroides cf. T. rhomboideus Wang sp. nov. (Figure 30, 1-4) Clade UNKNOWN Genus Glandilunatus Wang gen. nov. Glandilunatus minnesotense Wang sp. nov. (Figure 15, 7; Figure 29, 5) Genus Dicotylophyllum Saporta 1894 Dicotylophyllum braunii Wang sp. nov. (Figure 20, 5-6) Dicotylophyllum fragilis Wang sp. nov. (Figure 15, 8-9) Dicotylophyllum huangia Wang sp. nov. (Figure 30, 5-6) Dicotylophyllum sp. (Figure 24, 4-6) Genus Hickeyphyllum Wang gen. nov. Hickeyphyllum imhofia Wang sp. nov. (Figure 19, 9-10) Hickeyphyllum sandersia Wang sp. nov. (Figure 19, 4-6) Genus Kladoneuron Wang gen. nov.

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31 Kladoneuron gooleria Wang sp. nov. (Figure 23, 2-4) Hoisington III Locality, Kansas MAGNOLIIDS cf. Illiciaceae Genus Longstrethia Upchurch and Dilcher 1990 Longstrethia aspera (Lesquereux) Wang comb. nov. (Figure 44, 1-2; Figure 44, 5) cf. Chloranthaceae Genus Crassidenticulum Upchurch and Dilcher 1990 Crassidenticulum decurrens Upchurch and Dilcher 1990 (Figure 36, 5-6) Crassidenticulum variloba Wang sp. nov. (Figure 34, 1; Figure 36, 1) Crassidenticulum trilobus Wang sp. nov. (Figure 36, 2) Order MAGNOLIALES Genus Jarzenia Wang gen. nov. Jarzenia kanbrasota Wang sp. nov. (Figure 43, 6-7) Genus Liriophyllum Lesquereux 1878 Liriophyllum kansense Dilcher and Crane 1984 Order LAURALES cf. Lauraceae Genus Wolfiophyllum Wang gen. nov. Wolfiophyllum pfaffiana (Heer) Wang comb. nov. (Figure 35, 7; Figure 44, 3-4) Genus Rogersia Fontaine 1889 Rogersia potteri Wang sp. nov. (Figure 32, 2-3) Rogersia kansense Wang sp. nov. (Figure 35, 1-4; Figure 35, 6; Figure 35, 8) cf. Atherospermataceae, Gomortegaceae, Gyrocarpaceae, Lauraceae, Hernandiaceae, and Hortoniaceae Genus Pabiania Upchurch and Dilcher 1990 Pabiania variloba Upchurch and Dilcher 1990 (Figure 33, 1-4; Figure 33, 6-7) Pabiania groenlandica (Heer) Wang comb. nov. (Figure 19, 1-7) Pabiania cf. P. groenlandica (Heer) Wang comb. nov. (Figure 33, 5) Order PROTEALES cf. family Nelumbonaceae Genus Nelumbites Berry 1911 Nelumbites fluitus Wang sp. nov.

PAGE 40

32 (Figure 45, 1-7; Figure 46, 1; Figure 46, 3-4; Figure 47, 2) Nelumbites crassinervum Wang sp. nov. (Figure 46, 2; Figure 47, 1; Figure 47, 3-6) Nelumbites farleyi Wang sp. nov. (Figure 46, 6-7) aff. Platanaceae Genus Credneria Schwarzwalder and Dilcher 1986 Credneria cyclophylla (Heer) Wang comb. nov. (Figure 34, 4-6) Genus Sapindopsis Fontaine 1889 Sapindopsis bagleyae Wang sp. nov. (Figure 40, 1-5; Figure 39, 1-7; Figure 41, 1-7) Sapindopsis retallackii Wang sp. nov. (Figure 36, 3-4) Sapindopsis beekeria Wang sp. nov. (Figure 35, 5; Figure 42, 1; Figure 42, 4) EUDICOTS CORE EUDICOTS ROSIDS EUROSIDS II Genus Citrophyllum Berry 1911 Citrophyllum alteruans (Heer) Wang comb. nov. (Figure 48, 1-7) Genus Anisodromum Upchurch and Dilcher 1990 Anisodromum wolfei Upchurch and Dilcher 1990 (Figure 42, 2-3; Figure 42, 5-6) Anisodromum upchurchii Wang sp. nov. (Figure 43, 1-2; Figure 43, 5) Clade UNKNOWN Genus Skogia Wang gen. nov. Skogia leptoselis Wang sp. nov. (Figure 44, 6-7) Genus Dicotylophyllum Saporta 1894 Dicotylophyllum leptovena Wang sp. nov. (Figure 34, 2; Figure 48, 8) Genus Meiophyllum Wang gen. nov. Meiophyllum expansolobum (Upchurch and Dilcher) Wang comb. nov. (Figure 37, 1-6;Figure 38, 1-8) Meiophyllum kowalskiae Wang sp. nov. (Figure 34, 6; Figure 37, 7-8) Genus Jaramillophyllum Wang gen. nov. Jaramillophyllum celatus (Lesquereux) Wang comb. nov. (Figure 32, 1) Genus Wingia Wang gen. nov. Wingia anisos Wang sp. nov. (Figure 43, 3-4)

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33 Springfield and Pleasant Dale Localities, Nebraska MAGNOLIIDS Order MAGNLIALES Genus Jarzenia Wang gen. nov. Jarzenia kanbrasota (Heer) Wang comb. nov. (Figure 63, 5-8; Figure 50, 1-6; Figure 50, 9-10) Order LAURALES cf. family Lauraceae Genus Rogersia Fontaine 1889 Rogersia parlatorii Fontaine 1889 (Figure 65, 5-9) Rogersia cf. R. parlatorii Fontaine 1889 (Figure 65, 10-11) Rogersia kansense Wang sp. nov. (Figure 63, 4; Figure 64, 3; Figure 65, 1-4) Genus Pabiania Upchurch and Dilcher 1990 Pabiania variloba Upchurch and Dilcher 1990 (Figure 71, 1; Figure 71, 3; Figure 71, 6) Genus Manchesterii Wang gen. nov. Manchesterii macrophylla (Lesquereux) Wang comb. nov. (Figure 61, 1-6; Figure 52, 1-2; Figure 52, 4-6) EUDICOTS Order PROTEALES Dumort. cf. family Platanaceae Genus Sapindopsis Fontaine Sapindopsis retallackii Wang sp. nov. (Figure 66, 1-8; Figure 67, 1-5; Figure 63, 1-2) Family Platanaceae Genus Credneria Zenker emend. Schwarzwalder and Dilcher Credneria cf. Credneria cyclophylla (Heer) Wang comb. nov. (Figure 64, 4-5) Genus Eurylobum Schwarzwalder and Dilcher 1986 Eurylobum dentatum Lesquereux emend. Schwarzwalder and Dilcher 1986 (Figure 69, 1-2; Figure 69, 4-5; Figure 70, 1-4) Genus Aspidiophyllum Lesquereux emend. Schwarzwalder and Dilcher 1986 Aspidiophyllum obtusum (Lesquereux) Wang comb. nov. (Figure 68, 1-6; Figure 71, 2; Figure 71, 4-5) CORE EUDICOTS Order SAXIFRAGALES Dumort. cf. Cercidiphyllaceae Genus Trochodendroides Berry 1922 Trochodendroides rhomboideus (Lesquereux) Berry 1922 (Figure 64, 7; Figure 51, 1-7; Figure 51, 10) Clade UNKNOWN Genus Sungia Wang gen. nov.

PAGE 42

34 Sungia delicatus Wang sp. nov. (Figure 62, 1-5) Genus Meiophyllum Wang gen. nov. Meiophyllum expansolobum (Upchurch and Dilcher) Wang comb. nov. (Figure 64, 1-2; Figure 37, 1-8) Dicotylophyllum denticulatus Wang sp. nov. (Figure 64, 6) Quercophyllum tenuinerve Fontaine (Figure 64, 8) ? Menispermites sp. (Figure 68, 7) Courtland I Locality, Minnesota MAGNOLIIDS Order MAGNOLIALES Genus Jarzenia Wang gen. nov. Jarzenia kanbrasota Wang sp. nov. (Figure 50, 1-6; Figure 50, 9-10) Jarzenia reticulatus Wang sp. nov. (Figure 53, 1-3) Genus Liriophyllum (Lesquereux) Dilcher and Crane 1984 Liriophyllum siemia Wang sp. nov. (Figure 50, 11; Figure 58, 1-2; Figure 58, 6-7, Figure 58, 10-11) Order LAURALES cf. Family Lauraceae Genus Wolfiophyllum Wang gen. nov. Wolfiophyllum pfaffiana Wang sp. nov. (Figure 56, 8-12; Figure 58, 3-5; Figure 58, 8-9; Figure 60, 2-3) Rogersia kansense Wang sp. nov. (Figure 50, 7; Figure 51, 11-13; Figure 51, 15-16; Figure 60, 4) Genus Setterholmia Wang gen. nov. Setterholmia rotundifolia (Lesquereux) Wang comb. nov. (Figure 49, 2-7; Figure 49, 9-10) Setterholmia callii Wang sp. nov. (Figure 49, 1; Figure 49, 8) Setterholmia deleta (Lesquereux) Wang comb. nov. (Figure 60, 7-8) Genus Manchesterii Wang gen. nov. Manchesterii macrophylla (Lesquereux) Wang comb. nov. (Figure 52, 1-2; Figure 52, 4-6) Genus Crassidenticulum Upchurch and Dilcher 1990 Crassidenticulum cracendentis Wang sp. nov. (Figure 59, 1-5) Genus Densinervum Upchurch and Dilcher 1990 Densinervum kaulii Upchurch and Dilcher 1990 (Figure 60, 1, Figure 60, 5-6, Figure 60, 9-10)

PAGE 43

35 Genus Pandemophyllum Upchurch and Dilcher 1990 Pandemophyllum kvacekii Upchurch and Dilcher 1990 (Figure 54, 6-9) Pandemophyllum attenuatum Upchurch and Dilcher 1990 (Figure 53, 4-11) Pandemophyllum gracifolia Wang sp. nov. (Figure 53, 12-14) EUDICOTS PROTEALES Dumort. Genus Credneria Zenker 1883 Credneria cyclophylla (Heer) Wang comb. nov. (Figure 55, 1-7) CORE EUDICOTS Order SAXIFRAGALES Dumort. aff. family Cercidiphyllaceae Genus Trochodendroides Berry 1922 Trochodendroides rhomboideus (Lesquereux) Berry 1922 (Figure 51, 1-7; Figure 51, 10) Clade UNKNOWN Genus Dicotylophyllum Saporta 1894 Dicotylophyllum crasseprimus sp.nov. (Figure 59, 6-7) Dicotylophyllum carlsonia Wang sp. nov. (Figure 52, 3) Dicotylophyllum tulipifera (Heer) Wang comb. nov. (Figure 54, 10-12) Dicotylophyllum coughlantia Wang sp. nov. (Figure 57, 1-8) Dicotylophyllum leptovena Wang sp. nov. (Figure 51, 8-9; Figure 51, 14) Genus Crepetia Wang gen. nov. Crepetia minudentis Wang sp. nov. (Figure 56, 1-7) Genus Glandilunatus Wang gen. nov. Glandilunatus minnesotense Wang sp. nov. (Figure 54, 1-5) Similar to the floristic features of the Rose Creek I assemblage (Upchurch and Dilcher 1990), Magnoliids (34 species of 13 genera) and the order Proteales (14 species of 7 genera) are dominant angiosperm elements in the Dakota Flora. They comprise of about 50% of identified genera and 55% of identified species (Figure 5). Of the 87 identified species of 40 genera, none is assignable to extant genus (Figure 6). This is

PAGE 44

36 consistent with the observations of Upchurch and Dilcher (1990) and Dilcher (2000) based on the Rose Creek I assemblage of the Dakota Formation. Comparisons of the fossils angiosperm leaves with modern taxa are based on published literatures and those observations of Upchurch and Dilcher (1990) and Upchurch et al. (1994). Most species do not possess features that permits their placement within a modern family, but shows relationships with one or more extant families. All genera are extinct and the possession of many primitive characters indicates the archaic aspect of the Dakota Flora (Upchurch and Dilcher, 1990), although it is much more advanced compared with older Cheyenne Flora (Huang, 1989) and Potomac Flora (Hickey and Doyle, 1977). Systematics BraunÂ’s Ranch Locality, Kansas MAGNOLIIDS LAURALES Wolfiophyllum Hongshan Wang gen. nov. Generic diagnosis. Lamina lorate to linear; apex acute; base decurrent; petiole normal, short. Margin entire. Primary venation pinnate; primary vein moderate to stout, multistranded. Secondary venation eucamptodromous; secondary veins thick, multistranded, course sinuous to uniformly curved; angle of divergence very narrow acute, with upper pairs more obtuse than lower pairs; veins more densely arranged at the base; exmedial or admedial branches from secondary veins monopodially forking and diminishing to form tertiary veins; secondary veins on the proximal portion running almost parallel to the margin to a distance almost overlapping the superadjacent secondary vein; intersecondary veins present. Tertiary vein course irregular. Type species. Wolfiophyllum heigii .

PAGE 45

37 Derivation of generic name. In honor of Jack A. Wolfe and in recognition of his contributions to angiosperm paleobotany. Discussion. The new genus Wolfiophyllum is established for those Cretaceous leaves with entire margin, strong and multistranded primary venation, eucamptodromous secondary venation, and irregular secondary and higher order veins (Table 3). Wolfiophyllum heigii Hongshan Wang sp. nov. (Figure 17, 7-9; Figure 17, 11-12; Figure 19,7-8) Specific diagnosis. Lamina lorate to linear; apex acute; base decurrent; petiole normal, short. Margin entire. Primary venation pinnate; primary vein moderate to stout, multistranded, course straight or markedly curved. Secondary venation eucamptodromous; secondary veins thick, multistranded, course sinuous to uniformly curved in over view; angle of divergence very narrow acute, with upper pairs more obtuse than lower pairs; veins more densely arranged at the base; secondary veins predominantly fork at 2/3 distance from primary vein to leaf margin exmedial or admedial branches monopodially forking and diminishing to form tertiary veins; secondary veins on the proximal portion running almost parallel to the margin at a distance almost overlapping the superadjacent secondary vein; intersecondary veins present, 1 to 2 between two adjacent secondary veins, simple, composite or monopodially forking and integrading with tertiary veins. Tertiary vein course irregular, percurrent or exmedially ramified, course sinuous. Description. Whole lamina symmetrical to asymmetrical; base symmetrical asymmetrical; form lorate to linear, L/W ratio 6 to 10, 0.3 cm to 0.7 cm wide by 2.5 cm to 5 cm long; apex acute; base decurrent; petiole normal, short. Margin entire, strong

PAGE 46

38 marginal vein about 6 cells wide. Primary venation pinnate; primary vein moderate to stout, multistranded, course straight or markedly curved. Secondary venation eucamptodromous (secondary veins upturned and gradually diminishing apically inside the margin, connected to the superadjacent secondary veins by a series of cross veins without forming prominent marginal loops); secondary veins thick, multistranded, course sinuous to uniformly curved in brief view; angle of divergence very narrow acute (less than 30º), with upper pairs more obtuse than lower pairs; typically 10 to 12 secondary veins present (excluding those pairs at the extreme base which are tertiary or quaternary in order), with veins more densely arranged at the base; secondary veins predominantly fork at 2/3 distance from primary vein to l eaf margin exmedial or admedial branches monopodially forking and diminishing to form tertiary veins; secondary veins on the proximal portion running almost parallel to the margin at a distance almost overlapping the superadjacent secondary vein; intersecondary veins present, 1 to 2 between two adjacent secondary veins, simple, composite or monopodially forking and integrading with tertiary veins. Tertiary vein course irregular, percurrent or exmedially ramified (branching oriented toward the margin), course sinuous. Veins of higher order not observed. Number of specimens examined. 17. Holotype. UF15709-16379a. Paratypes. UF15709-16308; 16344; 24987, 24987’; 16258; 16301. Derivation of epithet. In honor of Vine Heig and in recognition of his contributions the collection of Dakota Formation specimens.

PAGE 47

39 Discussion. This species differs from other Dakota Formation linear, entire margined leaves by its eucamptodromous venation and its irregular higher order venation (Table 3). Wolfiophyllum daphneoides (Lesquereux) Hongshan Wang comb. nov. (Figure 26, 4-6) Embothrium? daphneoides Lesquereux, 1874,Cretaceous Flora, p.87, pl.30, Figure 10. Emended specific diagnosis. Leaf narrow ovate to lanceolate. Margin entire, conspicuously structurally reinforced. Primary venation pinnate; primary vein stout, straight, multistranded. Secondary venation eucamptodromous; secondary veins moderate, multistranded; angle of divergence uniform, narrow acute; secondary veins uniformly curved and gradually diminishing apically near the margin, connected to the superadjacent secondary veins without forming prominent loops near margin; intersecondary veins common, one per intercostal region, extend almost the same distance as adjacent secondary veins; intersecondary veins simple. Description. Leaf narrow ovate to lanceolate, L/W 2 to 3, lamina 4 cm to 6 cm long by 1.9 cm wide; apex missing; base narrow acute; petiole missing; margin entire, conspicuously structurally reinforced by marginal vein. Primary venation pinnate; primary vein stout, straight, multistranded (Figure 26, 6). Secondary venation eucamptodromous (Figure 26, 6); secondary veins moderate, multistranded, 5 to 7 pairs per lamina; angle of divergence uniform, narrow acute, less than 45 ; secondary veins uniformly curved and gradually diminishing apically near the margin, connected to the superadjacent secondary veins without forming prominent loops; intersecondary veins (Figure 26, 6) common, one per intercostal region, extend almost the same distance as

PAGE 48

40 adjacent secondary veins; intersecondary veins simple. Veins of higher order poorly preserved. Number of specimens examined. 4. Holotype. Wolfiophyllum daphneoides Lesquereux, 1874, Cretaceous Flora, p.87, pl.30, Figure 10. Paratype. UF15709-16491; 25002. Other specimens examined. UF15709-31288, 31288’; 31294. Discussion. Wolfiophyllum daphneoides is similar to “Litsea” falcifolia Lesquereux (Lesquereux, 1892) in leaf shape, eucamptodromous secondary venation, and secondary veins originating from the primary vein at very acute angles but they differ in that Wolfiophyllum daphneoides has multistranded primary vein and intersecondary veins. Likewise, it resembles “Litsea” cretacea Lesquereux (Lesquereux, 1892) in leaf shape, eucamptodromous secondary venation but it differs from it in having intersecondary veins and lacking percurrent tertiary veins. These two species are probably closely related to Wolfiophyllum daphneoides and represent one or two different species of the same genus. Wolfiophyllum daphneoides resembles some extant members of the Lauraceae, for example, Lindera angustifolia Cheng and Lindera fragrans Oliv. vel. aff. (Klucking, 1987), Litsea ferruginea Bl. (Klucking, 1987), Nectandra lanceolata Nees (Klucking, 1987), and Neolitsea cambodiana Lec. var. glabra Allen. (Yu and Chen, 1990) in having eucamptodromous secondary venation but it differs from them and in leaf shape and the presence of intersecondary veins. The following features such as entire margin, multistranded primary and secondary veins, eucamptodromous venation, and steep angle of secondary and

PAGE 49

41 intersecondary veins indicate its relationship with the Laurales. Within the Laurales, Wolfiophyllum daphneoides is possibly most closely related to Lauraceae, as indicated by its leaf shape, multistranded primary and secondary veins, and eucamptodromous venation. Crassidenticulum Upchurch and Dilcher 1990 Generic diagnosis (emended). Leaf simple or compound, even-pinnate; leaflet elliptic to oblong; petiole with a decurrent wing of a laminar tissue; margin predominately non-entire, with numerous very small teeth that possess well developed mechanical thickenings along the margin; tooth construction of the chloranthoid type. Primary venation pinnate; primary vein stout to massive. Secondary venation showing strong craspedodromous tendencies but with the secondary veins curving apically and tending to form loops with the superadjacent secondary veins before entering the teeth; secondary veins thin relative to primary vein, numerous, closely spaced. Intersecondary veins present. Tertiary venation reticulate, not rigidly organized. Higher order venation irregularly reticulate. Crassidenticulum decurrens Upchurch and Dilcher 1990 (Figure 25, 1-10; Figure 26, 1-3) Crassidenticulum decurrens Upchurch and Dilcher, 1990, p. 29, pl. 3; pl. 4;Text-Figure3. Celastrophyllum decurrens Lesquereux, 1892, p. 172, pl. 36, Figure1. Specific diagnosis. Same as for genus. Description. Leaf compound, even-pinnate, 5 to 7 leaflets attached distally at point of attachment of terminal leaflet, at least 4 other subtending leaflets pinnately arranged and perhaps in pairs; terminal leaflet symmetrical, lateral leaflet base

PAGE 50

42 asymmetrical, narrow elliptic to very narrow elliptic, L/W 4 to 8, lamina 0.9 cm to 2.5 cm wide by 4.8 cm long; apex retuse; base acute, decurrent; petiole normal, 1 mm to 2 mm wide by 1.5 cm to 2 cm long. Leaflet margin toothed; axes of serrations slightly inclined to the tangent of the margin, apical angle obtuse; serration type convex (basal side)convex (apical side); sinus rounded; 8 to 10 teeth per cm, regularly spaced; teeth simple (all of one size), present on upper 4/5 margin; glands marginal, on teeth as glandular thickenings, glands often not preserved. Primary venation pinnate; primary vein massive, course straight. Secondary venation mixed craspedodromous, secondary veins and tertiary branches on upper 4/5 lamina terminating at margin while those at base joining superadjacent secondary veins or exmedial branches of superadjacent secondary veins often forming conspicuous loops, irregular in shape and size; secondary veins thin, angle of divergence wide acute at 80 , with basal pairs more acute, decurrent on primary vein; course of secondary veins irregular, straight, slightly curved or recurved; secondary veins densely arranged, 5 to10 pairs per cm at middle portion of lamina, spacing irregular; behavior of loop-forming branches irregular , secondary veins at leaf base joining superadjacent secondary veins or exmedial branches of secondary veins to form irregular loops without terminating at margin, secondary veins on upper 4/5 lamina either terminating at tooth apex or branch to join exmedial branches of secondary veins, secondary veins, or intersecondary veins to form secondary or tertiary loops, which are irregular in shape and size, with long axes of the enclosed areas arranged predominately perpendicular or at a slight angle to the leaf margin; intersecondary veins common, simple, 1 to 2 per intercostal region; typically three veins terminating at a tooth apex, a single vein goes directly to the glandular thickenings on the tooth and another tertiary

PAGE 51

43 vein goes to the sinus, these veins originate as branches from secondary or tertiary loops near leaflet margin. Tertiary veins thin, randomly reticulate. Number of specimens examined. 125. Holotype. University of Kansas State Museum (UKSM) 7257 (See Upchurch and Dilcher, 1990). Paratypes. UF15709-11869; 16536; 16546; 24064, 24064Â’; 11111b, 1111bÂ’; 16545; 16396, 16396Â’; 16560; 30900; 16395, 16395Â’; 24036; 24041, 24041Â’; 20264, 20264Â’; 16540 (illustrated). Discussion. Compared with the type species described by Upchurch and Dilcher (1990), specimens from the BraunÂ’s Ranch Locality are better preserved, showing compound leaf, more variations of leaf shapes and well preserved petioles. All other characters are consistent with those of the type species. Upchurch and Dilcher (1990) assigned this genus to the Laurales; however, extant members of this order donÂ’t have compound leaves. See Table 4 for the difference between Crassidenticulum decurrens and other Crassidenticulum species. Crassidenticulum trilobus Hongshan Wang sp. nov. (Figure 21, 1-8; Figure 22, 1-6; Figure 23, 6-8) Specific diagnosis. Leaf simple, three lobed, notches more than 4/5 deep; sinus between lobes structurally reinforced. Leaf margin toothed with angular sinus; serrate axes inclined to the tangent of the margin; apical angle of tooth acute, serration type convex (basal side)-concave (apical side), convex-acuminate or straight-concave. Teeth simple, extent on complete margin except extreme base and between lobes; teeth vary from coarse to fine, some coarse teeth seem to be deciduous; on fine teeth, basal and

PAGE 52

44 apical side difficult to distinguish. Glands on the tooth apex as glandular seta; typically three veins (branches from secondary, tertiary or quaternary arches) terminating at the tooth apex. These veins or finer veins may form meshes irregular both in shape and size; no veins terminating at tooth sinus observed. Primary venation actinodromous; primary vein massive; position of primary vein suprabasal, perfect. Secondary veins thin; angle of divergence moderate to wide acute, with lowest pair more acute than those above; secondary veins decurrent on primary vein. Secondary vein spacing more or less irregular; course of secondary veins uniformly curved before joining exmedial branches of superadjacent secondary vein forming intercostal regions irregular in shape and size, while the rest joining exmedial branches of superadjacent secondary veins to form a series of secondary arches. These arches and the parallel exmedial branches enclose elongate areas with long axes perpendicular to the margin. Intersecondary veins common, 1 to 3 per intercostal region; angle of divergence from primary vein more obtuse than that of secondary veins. Description. Leaf simple, three lobed, sinus more than 4/5 deep; sinus between lobes structurally reinforced by lamina tissue. Both whole leaf and base symmetrical; form very wide obvate, L/W ratio 1, leaves variable in size from very small to large; lamina 4.5 cm to 20 cm wide by 4.5 cm to 16 cm long (estimated maximum width and length). Apex attenuate or obtuse. Base normal obtuse; petiole inflated, sometimes with paired lateral emergencies on basal ½ and at the petiole base; petiole up to 2 mm wide by 6 cm long. Leaf margin toothed with angular sinus; serrate 5 to 10 teeth per cm, axes inclined to the tangent of the margin; apical angle of tooth acute, serration type convex (basal side)-concave (apical side), convex-acuminate or straight-concave (these three

PAGE 53

45 types can occur on one leaf); teeth simple (all of one size), rarely compound (teeth in two sizes), present on complete margin except extreme base and between lobes. Teeth vary from coarse to fine, some coarse teeth seem to be deciduous; on fine teeth, basal and apical side difficult to distinguish; glands ma rginal, on the teeth apex as glandular seta; typically three veins (branches from secondary, tertiary or quaternary arches) terminating at the tooth apex, these veins finer veins may form meshes irregular both in shape and size; no veins terminating at tooth sinus observed. Primary venation actinodromous (three primary veins diverging radically al most from a single point); primary veins massive, course straight; position of primary veins suprabasal, perfect (lateral basilar primary veins cover more than 2/3 of lamina). Middle lobe symmetrical while lateral lobes asymmetrical; lobe elliptic to narrow oblong; 1 cm to 3 cm wide by 3 cm to 16 cm long (estimated ultimate length). Secondary veins thin, up to 15 pairs per lobe; angle of divergence moderate to wide acute (45 to 80 ), with lowest pair more acute than those above; secondary veins decurrent on primary veins, spacing more or less irregular; course of secondary veins uniformly curved before joining exmedial branches of superadjacent secondary vein (usually ½ to 2/3 distance from primary vein to margin), forming intercostal regions irregular in shape and size, while the rest joining exmedial branches of superadjacent secondary veins to form a series of secondary arches; these arches and the parallel exmedial branches (almost perpendicular to margin) enclosing elongate areas with long axes perpendicular to the margin. Intersecondary veins common, 1 to 3 per intercostal region, extending less than ½ distance before joining superadjacent secondary or intersecondary veins to form arches; angle of divergence from primary vein more

PAGE 54

46 obtuse than that of secondary veins. Tertiary veins poorly preserved. Some specimens lack details of secondary and higher order venation and almost appearing chartaceous. Number of specimens examined. 58. Holotype. UF15709-11892 Paratypes. UF15709-16553; 11894; 11108; 16556; 16409, 16409'; 3998, 3998', 3998"; 24157. Derivation of epithet. Latin, “tri-“ means “three,” “-lobus” means “lobe,” referring to the three lobed leaves. Discussion. Among described dicot fossil leaves from the Dakota Formation, “Aralia” formosa Heer (Heer, 1869; Lesquereux, 1883) is similar to Crassidenticulum trilobus in overall appearance, but they differ in that Crassidenticulum trilobus possesses finer teeth, longer and relative thinner petiole, and more oblong lobes than “Aralia” formosa . See Table 4 for the difference between Crassidenticulum trilobus and other Crassidenticulum species. Crassidenticulum landisae Hongshan Wang sp.nov. (Figure 27, 1-9; Figure 28, 1-5) Specific diagnosis. Leaf simple; base acute, decurrent; petiole inflated at base. Leaf margin toothed; serrations axes inclined to the tangent of the margin, apical angle acute, serration concave, straight or convex (b asal side) to concave (apical side); tooth sinus rounded; teeth spacing regular, teeth si mple; glands on tooth apex as glandular thickenings; glandular thickening extend along the basal side of tooth; typically one exmedial branch from secondary vein near margin or a secondary vein terminate at the apical side of tooth, thinner branches may emerge with marginal vein running parallel

PAGE 55

47 along the basal side of tooth; glandular t ooth apex may be deciduous. Primary venation pinnate; primary vein stout to massive, multistranded; course straight or markedly curved. Secondary venation craspedodromous; secondary veins subopposite, regularly spaced; angle of divergence moderate acute, with lowest pair more acute than pairs above; intersecondary veins present. Tertiary veins in the intercostal region tending to be percurrent, course sinus, arrangement predominately alternate, spacing irregular. Quaternary veins moderate, randomly oriented, course sinuous. Quinternary veins reticulate, arising from quaternary or tertiary veins at irregular angles to form close venation. Marginal ultimate venation incomplete, quaternary in order, terminate perpendicularly at the sinus or basal side of tooth. Description. Leaf simple, whole lamina and base of leaf symmetrical, narrow elliptic to narrow oblong, L/W 3 to 4, 1.5 cm to 3.5 cm wide by 4.5 cm to 12 cm long (estimated maximum length); apex probably retu se to acute; base acute, decurrent; petiole inflated at base, 0.5 cm to 2 mm wide by 1.8 mm to 2.1 mm long. Leaf margin toothed; serrations axes inclined to the tangent of the margin, apical angle acute, serration concave, straight or convex (basal side) to concave (apical side); tooth sinus rounded; 4 to 7 teeth per cm, spacing regular; teeth simple (all of one size), basal ¼ to 1/5 usually lacking teeth; glands on tooth apex as gla ndular thickenings; glandular thickening extend along the basal side of tooth; typically one exmedial branch from secondary vein near margin or a secondary vein terminate at the apical side of tooth, thinner branches may emerge with marginal vein running parallel al ong the basal side of tooth; glandular tooth apex may be deciduous. Primary venation pinnate; primary vein stout to massive, multistranded; course straight or markedly curved. Secondary venation craspedodromous

PAGE 56

48 (secondary veins and their exmedial branches terminating at teeth apex); on the same specimen, secondary venation may be semicraspedodromous (secondary veins branching just within the margin, one of the branches terminating at the margin, the other joining the superadjacent secondary veins); typically 9 to 12 pairs per lamina, subopposite, regularly spaced; angle of divergence moderate acute (about 50°), with lowest pair more acute than pairs above; course uniformly curved but more or less sinuous; intersecondary veins present, composite (made up of coalesced tertiary vein segments for over 50% of its length). Tertiary veins in the intercostal region tending to be percurrent, course sinus, arrangement predominately alternate, spacing irregular. Quaternary veins moderate, randomly oriented, course sinuous. Quinternary veins reticulate, arising from quaternary or tertiary veins at irregular angles to form close venation. Marginal ultimate venation incomplete, quaternary in order, terminate perpendicularly at the sinus or basal side of tooth. Number of specimens examined. 13 Holotype. UF15709-23280, 23280’. Paratypes. UF15709-6541; 16549, 16549’; 24043; 24070; 24063, 24063’. Derivation of epithet. In honor of Margaret Landis, and in recognition of her contributions to Dakota Formation paleobotany. Discussion. Crassidenticulum landisae can be distinguished from other toothed species (Table 4) from the Braun’s Ranch locality by the fact that Crassidenticulum decurrens has numerous, thinner, and more irregular secondary veins . Crassidenticulum trilobus is trilobed and has secondary veins, which are more widely spaced and originate from primary veins at more obtuse angles. Yangia glandifolium has a strong primary

PAGE 57

49 vein, numerous and thinner secondary veins, finer teeth on margin and oil glands all over the lamina (Figure 29, 2). Landonia Upchurch and Dilcher 1990 Generic diagnosis. See Upchurch and Dilcher (1990). Landonia mullerii Hongshan Wang sp. nov. (Figure 23, 5) Specific diagnosis. Leaf simple, narrow obvate, base acute cuneate; petiole normal; margin entire, with marginal vein. Primary venation pinnate; primary vein massive, multistranded. Secondary venation brochidodromous; secondary veins thin relative to primary vein, multistranded, widely spaced; secondary veins decurrent on primary vein, lowest pair more acute than pairs above; secondary veins uniformly curved, joining exmedial branches of superadjacent secondary veins to form a series of prominent loops; basal pair of secondary veins thin, joining veins arising from primary vein at obtuse angles to form a prominent series of loops; intersecondary veins present, possibly composite, extending to only half distance from primary vein to margin. Tertiary veins moderate relative to secondary veins; angle of divergence from secondary veins or intersecondary veins predominantly right (admed ial side)-right (exmedial side); pattern of tertiary veins tend to be percurrent, course straight or retroflexed; primary-tertiary vein angle oblique, arrangement predominantly alternate. Quaternary veins thin, randomly reticulate. Ultimate veins near fimbriate, branches arising from secondary arches fused into a very thin vein running along the margin. Description. Leaf simple, narrow obvate, L/W 2.3, lamina 3 cm long by 1.3 cm wide; apex missing; base acute cuneate; petiole normal, 10 mm long by 8 mm wide;

PAGE 58

50 margin entire, with marginal vein. Primary venation pinnate; primary vein massive, multistranded, slightly curved. Secondary venation brochidodromous; secondary veins thin relative to primary vein, multistranded, about 10 secondary veins present, widely spaced relative to leaf size; secondary veins decurrent on primary vein, angle of divergence moderate acute (45 to 65 ), with lowest pair more acute than pairs above; secondary veins uniformly curved, joining exmedial branches of superadjacent secondary veins to form a series of prominent loops; basal pair of secondary veins thin, joining veins arising from primary vein at obtuse angles to form a prominent series of loops; intersecondary veins present, possibly composite, extending to only half distance from primary vein to margin. Tertiary veins moderate relative to secondary veins; angle of divergence from secondary veins or intersecondary veins predominantly right-right; pattern of tertiary veins tend to be percurrent, course straight or retroflexed; primarytertiary vein angle oblique, arrangement predominantly alternate. Quaternary veins thin, randomly reticulate. Ultimate veins near fimbriate, branches arising from secondary arches fused into a very thin vein running along the margin. Number of specimens examined. 1. Holotype. UF15709-16465. Derivation of epithet. In honor of Michael Muller and in recognition of his contributions to the collection of Dakota Formation specimens. Discussion. The following characters are consistent with the generic diagnosis for Landonia , a genus set up by Upchurch and Dilche r (1990) for Cretaceous angiosperm: massive multistranded primary vein; brochidodromous secondary venation; widely space

PAGE 59

51 secondary veins; larger angles of divergence; thin basal pair of secondary veins forming prominent loops; marginal vein about 2 cells wide, very inconspicuous. Yangia Hongshan Wang gen. nov. Generic diagnosis. Leaf margin toothed; serrate axes inclined to the tangent of the margin, apical angle obtuse; serration t ype convex (basal side-convex (apical side); sinus rounded; teeth simple. Glands occur on lamina and margin; glands on lamina irregularly distributed; marginal glands on t ooth apex as glandular thickenings. Primary venation pinnate; primary vein massive, straight, multistranded. Secondary venation festooned brochidodromous; secondary veins very thin relative to primary vein; closely arranged; course straight at ½ to 1/3 half leaf lamina; intersecondary veins common, simple. Derivation of generic name. In honor of Professor Guanxiu Yang and in recognition of her contributions to the Chinese paleobotany. Discussion. The new genus, Yangia , is set up to represent those Dakota Formation angiosperm leaves with toothed margin, oil glands on leaf lamina, massive multistranded primary vein, festooned brochidodromous secondary venation, and common intersecondary veins. Yangia glandifolium Hongshan Wang sp. nov. (Figure 29, 1-4; Figure 30, 7-8) Specific diagnosis. Same as for genus. Description. Leaf length over 10 cm, width at least 4 cm; apex missing; base normal, obtuse; basal portion of petiole missing. Most of the margin missing, observed margin toothed; serrate axes inclined to the tangent of the margin, apical angle obtuse;

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52 serration type convex (basal side)-convex (apical side); sinus rounded; teeth simple, 7 per cm, probably on the entire margin. Glands laminar and marginal; glands on lamina 0.2 mm in diameter, 100 to 120 glands per cm2, irregularly distributed; marginal glands on teeth as glandular thickenings. Primary vena tion pinnate; primary vein massive, straight, multistranded, at least 3 mm wide. Secondary venation festooned brochidodromous; secondary veins very thin relative to primary vein; closely arranged, 5 to 6 per cm; angle of divergence right (80 to 85 ); course straight before joining superadjacent branches of secondary veins at ½ to 2/3 distance of half leaf lamina to form loops; secondary loops typically enclosed by tertiary and quaternary loops; intersecondary veins common, simple, 1 to 3 per intercostal region, almost the same thickness as that of secondary veins. Tertiary veins in intercostal region thin, tending to be percurrent, irregularly spaced. Veins of higher order not observed. Number of specimens examined. 2. Holotype. UF15709-4754. Paratype. UF15709-31012. Derivation of epithet. Latin, “glandi-“ means “glandular,” and “folium” means “leaf,” referring to glands on leaf lamina. Discussion. Yangia glandifolium possesses glandular bodies that are distributed on the leaf lamina between the veins, possibly produced by crystallized organic contents of oil cells. Yangia glandifolium is easy to be distinguished from other toothed leaves (Table 4) of the Dakota Formation by its strong primary vein, thin and numerous secondary veins and oil glands distributed on the leaf lamina. Rogersia Fontaine 1889

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53 Emended generic diagnosis. Lamina base acute, cuneate, demarcation between lamina and petiole indistinct. Margin entire. Petiole normal. Primary venation pinnate; primary vein stout, multistranded. Secondary venation brochidodromous; secondary veins moderate in thickness, irregularly spaced; angle of divergence narrow acute, with lowest pairs more acute than those above and much thinner; course of secondary veins sinuous, joining superadjacent secondary veins or exmedial branches of superadjacent secondary veins at obtuse angles to form very irregular loops; intercostal area very elongate and admedially oriented; order of arches (secondary to quaternary) in excostal region indistinct and irregular in shape, but all elongate and tending to be parallel oriented to the margin; intersecondary veins common, difficult to distinguish from secondary veins by thickness. Tertiary veins thick, sometimes integrading with intersecondary or quaternary veins, tending to be percurrent; angle of origin irregular, predominately acute-obtuse (AO), course stra ight convex, relationship to primary vein (primary vein-tertiary vein angle) irregular; arrangement predominately alternate. Quaternary veins moderate in thickness, randomly oriented, integrading with tertiary or quinternary veins. Quinternary veins moderate in thickness, randomly oriented, either integrading with quaternary veins or forking once or twice to form an open venation. Type species. Rogersia longifolia Fontaine, 1889, pl. 139, Figure 6; pl. 144, Figure 2; pl. 150, Figure 1; pl. 109, Figures 1-2) Discussion. The genus Rogersia was set up by Fontaine in 1889. However, he did not designate a type species for this genus. Diagnostic characters of this genus, such as entire margin, multistranded primary venation, brochidodromous secondary venation,

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54 common intersecondary veins, and integrading higher order veins indicate its relationship within the Laurales. Rogersia parlatorii Fontaine 1889 (Figure 17, 1-6; Figure 17, 10; Figure 18, 1-11; Figure 23, 1) “Andromeda” parlatorii Heer, Lesquereux, 1874, p.88, pl.23, Figures 6-7; pl.28, Figure 15. Rogersia angustifolia Fontaine, 1889, Potomac or Younger Mesozoic Flora, pl. 143, Figure2; pl. 149, 4, 8; pl. 15, Figures 2-7. Specific diagnosis. Leaflet (whole lamina) form oblong, lorate to linear; apex acuminate with a sharp tip; base acute, cuneate, demarcation between lamina and petiole indistinct. Margin entire. Petiole normal. Primary venation pinnate; primary vein stout, multistranded, course straight, or markedly curved. Secondary venation brochidodromous; secondary veins moderate in thickness, irregularly spaced; angle of divergence narrow acute, with lowest 3 to 5 pairs more acute than those above and much thinner; course of secondary veins sinuous, joining superadjacent secondary veins or exmedial branches of superadjacent secondary veins at obtuse angles to form very irregular loops; intercostal area very elongate and admedially oriented; order of arches (secondary to quaternary) in excostal region indistinct and irregular in shape, but all elongate and tending to be parallel oriented to the margin; intersecondary veins common, difficult to distinguish from secondary veins by thickness, one (occasionally two) per intercostal area. Tertiary veins thick, sometimes integrading with intersecondary or quaternary veins, tending to be percurrent; angle of origin irregular, predominately acuteobtuse (AO), course straight convex, relationship to primary vein (primary vein-tertiary

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55 vein angle) irregular; arrangement predominately alternate. Quaternary veins moderate in thickness, randomly oriented, integrading with tertiary or quinternary veins. Quinternary veins moderate in thickness, randomly oriented, either integrading with quaternary veins or forking once or twice to form an open venation. Description. Leaflet (whole lamina) symmetrical, base symmetrical to slightly asymmetrical; form oblong, lorate to linear, L/W ratio 6 to 10 or more, lamina 0.4 cm to 1.4 cm wide by 3 cm to 12.5 cm long; apex acuminate with a sharp tip; base acute, cuneate, demarcation between lamina and petiole indistinct. Margin entire. Petiole normal, up to 1 mm wide and 6 mm long. Primary venation pinnate; primary vein stout, multistranded, course straight, or markedly curved. Secondary venation brochidodromous; secondary veins moderate in thickness, irregularly spaced; angle of divergence narrow acute (less than 45 ), with lowest 3 to 5 pairs more acute than those above and much thinner; course of secondary veins sinuous, joining superadjacent secondary veins or exmedial branches of superadjacent secondary veins at obtuse angles to form very irregular loops; intercostal area very elongate and admedially oriented; order of arches (secondary to quaternary) in excostal region indistinct and irregular in shape, but all elongate and tending to be parallel oriented to the margin; intersecondary veins common, difficult to distinguish from secondary veins by thickness, one (occasionally two) per intercostal area. Tertiary veins thick, sometimes integrading with intersecondary or quaternary veins, tending to be percurrent; angle of origin irregular, predominately acute-obtuse (AO), course stra ight convex, relationship to primary vein (primary vein-tertiary vein angle) irregular; arrangement predominately alternate. Quaternary veins moderate in thickness, randomly oriented, integrading with tertiary or

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56 quinternary veins. Quinternary veins moderate in thickness, randomly oriented, either integrading with quaternary veins or forking once or twice to form an open venation. Number of specimens examined. 195. Paratypes. UF15709-16511; 16512, 16512’; 16457; 16497, 16497’; 16275, 16275’; 16259, 16259’; 11865; 11862; 16269; 16458; 16267; 11874. Discussion. More secondary veins, densely arranged; indistinguishable elongate intercostal region; integrading secondary, tertiary veins and quaternary veins are diagnostic characters for this species. Lesquereux (1874) described some Dakota Formation specimens and assigned them to “ Andromeda ” parlatorii Heer (Lesquereux, 1874, p.88, pl.22, Figures 6-7; pl.28, Figure 15). H eer (1874) also used the same name. Fontaine (1889) assigned some Potomac specimens (Fontaine, 1889, Potomac or Younger Mesozoic Flora, pl. 143, Figure2; pl. 149, Figures 4, 8; pl. 150, Figures 2-7.) to Rogersia angustifolia . Based on leaf venation patterns, Fontaine’s specimens are the same as described by Lesquereux (1874). Based on 11.3. of International Code of Botanical Nomenclature (IAPT-International Association for Plant Taxonomy,2001), “For any taxon from family to genus inclusive, the correct name is the earliest legitimate one with the same rank, except in cases of limitation of priority by conservation (see Art. 14) or where Art. 11.7, 15, 19.4, 56, 57, or 59 apply.” The correct species epithet should be parlatorii . Rogersia lottii Hongshan Wang sp. nov. (Figure 19,1-3) Specific diagnosis. Lamina form narrow elliptic; base decurrent, acute; petiole normal, short. Margin entire, with structural reinforcement. Primary venation pinnate;

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57 primary vein stout, multistranded, course markedly curved. Secondary venation festooned brochidodromous; secondary veins thick, angle of divergence moderate acute, with lowest pair more acute than pairs above; course abruptly curved, joining superadjacent secondary veins at obtuse angle to form prominent loops which are enclosed by tertiary and quaternary loops; intersecondary veins present, simple. Tertiary veins thin. Description. Both whole lamina and base asymmetrical; form narrow elliptic, L/W 5, 1 cm wide by 5 cm long (estimated maximum length); apex missing; base decurrent, acute; petiole normal, short, 5 mm long by 0.9 mm wide. Margin entire, with structural reinforcement. Primary venation pinnate; primary vein stout, multistranded, course markedly curved. Secondary venation festooned brochidodromous; secondary veins thick, about 20 secondary veins present, angle of divergence moderate acute, with lowest pair more acute than pairs above; course abruptly curved, joining superadjacent secondary veins at obtuse angle to form prominent loops which are enclosed by tertiary and quaternary loops; intersecondary veins present, simple; intersecondary veins not well differentiated from secondary veins. Tertiary veins thin, with no specific pattern observed. Number of specimens examined. 1. Holotype. UF15709-12524, 12524Â’. Derivation of epithet. In honor of Terry Lott and in recognition of his contributions to the collection of Dakota Formation specimens. Discussion. The following characters can be used to distinguish this species from other entire margined leaves from BraunÂ’s Ranch locality: relatively thick secondary

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58 venation forming prominent secondary loops; entire and structurally reinforced margin; and intersecondary veins sometimes not well differentiated from secondary veins in thickness (Table 3). CORE EUDICOTS SAXIFRAGALES Dumort. Trochodendroides Berry 1922 Trochodendroides cf. T. rhomboideus (Lesquereux) Berry 1922 (Figure 30, 1-4) Specific diagnosis. Leaf simple, form suborbiculate; apex acuminate; base acute, decurrent; petiole inflated at base. Basal margin entire, distal ¾ to 4/5 portion toothed; teeth simple; glands on the tooth as a glandular. Primary venation acrodromous; diverging point basal, perfect; primary vein stout, multistranded, course straight, extending directly to the apex; lateral primary veins stout, multistranded, course markedly curved, extending more than 5/6 distance to the apex before joining secondary veins from primary vein; lateral primary veins may form 1 to 2 conspicuous exmedial branches. Secondary veins from middle primary vein branching ½ to 2/3 distance from lateral primary veins; secondary veins thin, intergrading with tertiary veins toward apex and base and exmedially. Exmedial secondary veins from lateral primary veins thick, uniformly curved to join superadjacent veins forming secondary arches; the lowest pair running parallel to the margin and extending 1/5 to 1/4 distance to the apex before joining superadjacent secondary veins to form arches; typically three adjacent branches from the arches merge at tooth apex, one vein extends into the tooth branching to form two opposite lateral veins going to tooth margin while the central vein continues into the

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59 glandular tip, also from the looping tertiary veins one unbranched vein extends directly to the tooth sinus. Tertiary veins thin, randomly reticulate. Quaternary veins relatively randomly oriented either anastomosing to form imperfect areoles or forming simple curved veinlets. Very thin marginal vein or slightly reinforced margin present on leaf and tooth margins. Description. Leaf simple, whole lamina and base of leaf symmetrical; form suborbiculate, L/W 1.6, 2.6 cm to 3.2 cm wide by 4.5 cm to 5 cm long; apex acuminate; base acute, decurrent; petiole inflated at base, 0.5 mm wide by 2 cm long. Basal margin entire, distal ¾ to 4/5 portion toothed (margi n having projections with pointed glandular apexes; axes of serration inclined to the tangent of the margin, apical angle acute, serration type convex (basal side)-acuminate (apical side); sinus angular; spacing of serrations regular, 5 to 6 teeth per cm; teeth simple (all of one size; glands on the tooth as a glandular seta, glandular tips of teeth may be deciduous. Primary venation acrodromous (two lateral primary veins running in convergent arches toward the leaf apex, arches not recurved at base); diverg ing point basal, perfect; primary vein stout, multistranded, course straight, extending directly to the apex; lateral primary veins stout, multistranded, course markedly curved, extending more than 5/6 distance to the apex before joining secondary veins from primary vein; lateral primary veins may form 1 to 2 conspicuous secondary veins exmedially and other minor secondary veins. Secondary veins from the middle primary vein branching at ½ to 2/3 distance from lateral primary veins; secondary veins thin, intergrading in order with tertiary veins toward apex and base and exmedially, either straight in course and extending directly to join lateral primary veins, or recurved to join admedial branched from lateral primary veins. Some

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60 exmedial secondary veins from the lateral primary veins may be thick, uniformly curved to join superadjacent veins forming secondary arches; the lowest pair running parallel to the margin and extending 1/5 to 1/4 distance to the apex before joining superadjacent secondary veins to form arches; typically three adjacent branches of these arches merge near the tooth apex. One vein extends into the tooth, branching to form two opposite lateral veins going to tooth margin while the central vein continues into the glandular tip, also from the looping tertiary veins one unbranched vein extends directly to tooth sinus. Tertiary veins thin, randomly reticulate. Quaternary veins relatively randomly oriented either anastomosing to form imperfect areoles (meshes of irregular shape, more or less variable in size) or forming simple curved veinlets. Very thin marginal vein or slightly reinforced margin present on leaf and tooth margins. Number of specimens examined. 3. Holotype. UF15709-11860. Paratypes. UF15709-11861; 11897. Discussion. Trochodendroides cf. T. rhomboideus is similar to Trochodendroides rhomboideus (Figure 51, 1-7; Figure 51, 10) but they differ in that the leaves of Trochodendroides rhomboideus are wide ovate to very wide ovate (rhomboidal) with rounded tooth apices. Trochodendroides cf. T. rhomboideus has more acute leaf base and acuminate tooth apex. EUDICOTS PROTEALES PLATANACEAE Credneria Zenker emend. Schwarzwalder and Dilcher 1986

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61 Credneria quadratus (Lesquereux) Hongshan Wang comb. nov. (Figure 24, 1-3) Pterospermites quadratus Lesquereux, 1871, p.301. Protophyllum quadratum Lesquereux, 1874, p.104, pl.19, Figure 1. Protophyllum pterospermitfolium , Lesquereux, 1892, p.195, pl.59, Figure 1. Specific diagnosis (emended). No specific diagnosis was provided by Lesquereux (1871, 1874, 1892) when he published this species. Leaf simple, margin entire, shape orbiculate, base strongly auricular, apex rounded. Primary venation pinnate. Secondary venation simple craspedodromous; secondary veins thick relative to primary veins, with lower pairs more densely arranged at basal 1/3 portion of lamina; secondary veins alternate, angle of divergence moderate acute, with upper pairs more acute than lower pairs; course of secondary veins straight, terminating at the margin; typically 1 to 2 exmedial branches per secondary vein. The basal four pairs of secondary veins crowded to at leaf base; all the major branches of secondary veins terminate at the margin; the basal most 2 to 3 pairs of secondary veins camptodromous; Tertiary veins moderate; angle of origin predominantly right-right, percurrent; course straight, but those originating from primary veins and 1 to 4 from proximal portion of secondary veins convex; relationship to primary vein oblique, primary vein-tertiary vein angle increases upward; arrangement predominantly alternate. Quaternary veins moderate, course orthogonal (arising at right angles); qui nternary veins moderate, orthogonal, anastomosing to form imperfect areoles; veinlets simple curved or branching once forming open venation.

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62 Description. Leaf orbiculate, L/W 1, lamina 7.2 cm wide by 7.2 cm long; apex rounded; base strongly auriculate, but appearing peltate; petiole incomplete, 1.5 mm wide by 4 cm long, with basal portion missing; margin entire. Primary venation pinnate; primary vein stout, course straight. Sec ondary venation simple craspedodromous (all of the secondary veins and their branches terminating at the margin); secondary veins thick relative to primary veins, 7 pairs per lamina, with lower 4 pairs densely arranged at basal 1/3 portion of lamina; secondary veins alternate, angle of divergence moderate acute (45 to 65 ), with upper pairs more acute than lower pairs; course of secondary veins straight, terminating at the margin; typically 1 to 2 exmedial branches per secondary vein; all the major branches of secondary veins terminate on the margin; the basal most 2 to 3 pairs of secondary veins produce exmedial loops; the secondary veins expand slightly into a possible glandular body at the leaf margin; hydathodes present. Tertiary veins moderate; angle of origin predominantly right (lower side)-right (upper side), percurrent; course straight, but those originating from primary ve ins and those one to four from lower side of secondary veins convex (middle portion of the veins curving away from the center of the leaf); relationship to primary vein oblique, primary-tertiary vein angle increases upward; arrangement predominantly alternate, close (interval between veins less than 0.5 cm). Quaternary veins moderate, course or thogonal (arising at right angles); quinternary veins moderate, orthogonal, anastomosing to form imperfect areoles; veinlets simple curved or branching once forming open venation. Number of specimens examined . 1. Holotype. Credneria quadratus , Lesquereux, 1874, p.104, pl.19, Figure 1. Paratype. UF15709-14835.

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63 Discussion. The genus Credneria was originally set up by Zenker (1883). Lesquereux (1874) assigned similar specimens from the Dakota Formation to the genus Protophyllum . Schwarzwalder (1986) suggested that the difference between the two genera on the basis of perfoliate leaves in Protophyllum and the presence of craspedodromous secondary venation in combination with entire or undulate margins had little significance. Therefore, the two genera should be merged. I follow Schwarzwarlder’s (1986) emendation. Credneria quadratus from Braun’s Ranch locality differs from other platanoid leaves in having: auricular base; 3 to 4 pairs of basal secondary veins clustered at the base, with lower most pair thin and camptodromous (not terminating at the margin), second pair curving downward and craspedodromous; arrangement of secondary veins on the primary vein changes from opposite at the base to subopposite in the middle and alternate on the upper portion of the leaf. Credneria quadratus differs from Credneria cyclophylla (Heer) Wang (Figure 55, 1-7) found at the Courtland I locality in that the latter has fewer secondary veins despite the size variation, cuneate or cordate base, and one pair of basal secondary veins with more exmedial branches (sometime may be up to 7). Dischidus Schwarzwalder and Dilcher 1986 Specific diagnosis. “Fossil leaf, lamina undivided, with five distinct lobes, petiolate; angle of leaf base narrow ( 60°) to moderate (> 60°, 180°), sometimes decurrent; lamina apex often acuminate, sometimes broad (> 60°); incision between lobes deep and pronounce (> 3/4 distance to mid-lamina); angle between adjacent lobes small ( 45°); primary venation palinactinodromous; suprabasal primary veins robust, equal in

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64 strength to central primary vein; angle between suprabasal primary veins narrow ( 45°) to moderate (> 45°, 100°); secondary veins mostly craspedodromous, may be camptodromous near base of lamina; secondary veins arising at moderate (> 25°, < 50°) to large ( 50°) angles; tertiary veins convex in axils of primary vein, percurrent to reticulate, tertiary veins closely spaced ( 3.5 mm apart); higher order veins orthogonal to highly orthogonal; quaternary veins moderately spaced (> 0.8 mm, 1.5 mm apart) (Schwarzwalder, 1986).” Dischidus quinquelobus Hongshan Wang sp. nov. (Figure 20, 1-4) Specific diagnosis. Leaf five lobed, stipulate, sinuses between major lobes rounded. Margin toothed with rounded sinus, serrations inclined to the tangent of the margin; apical angle of tooth acute, serration type convex-convex; teeth simple or occasionally compound; spacing regular, extent on 1/ 2 to 2/3 of lobes; marginal glands at tooth apex as glandular thickenings; petiole base inflated, stipulate. Primary venation palinactinodromous; primary veins massive, multistranded; position of primary veins perfect. Secondary venation craspedodromous; secondary veins thick, subopposite to alternate, extending directly to tooth apex without branching (craspedodromous); angle of divergence uniform, moderate acute; secondary veins extend to and fork at the major sinuses between the lobes. Tertiary veins moderate relative to secondary veins, percurrent; primary-tertiary vein angle oblique and constant; arrangement of tertiary veins predominately alternate. Quaternary veins thin, course orthogonal, transverse to tertiary veins. Conspicuous marginal veins present. In tooth sinus, tertiary veins fork and these branches join with marginal veins before terminating at glandular tooth apex;

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65 three veins merge at the tooth apex, consisting one secondary vein and two marginal veins. Description. Leaf five lobed, stipulate, sinuses between major lobes rounded. Leaf symmetrical; base symmetrical, form very wide obvate, L/W 0.8, 5 cm wide by 4 cm long (distance from lowermost position of lamina to middle lobe apex); base cordate. Margin toothed with round sinus, axes of serrations inclined to the tangent of the margin; apical angle of tooth acute, serration type c onvex (basal side)-convex (apical side); teeth simple (of the same size) or occasionally compound (secondary teeth present); spacing regular, extent on 1/2 to 2/3 of lobes; marg inal glands (or possibly hydathodes) at tooth apex as glandular thickenings, about 0.5 mm in diameter. Petiole base inflated, 1 mm wide by 12 mm long, two stipules (Figure 20, 4) attached to petiole base, stipules 3 mm to 5 mm long by 2 mm to 3 mm wide. Primary venation palinactinodromous (primary veins having two lateral subsidiary points of radiation above the lowest point); primary veins massive, multistranded, course straight; position of primary veins perfect (lateral primary veins cover more than 2/3 of lamina), marginal (primary veins terminating at margin); middle lobe symmetrical, lateral lobes with basal secondary lobes slightly asymmetrical at the base; lobes narrow obvate; 0.7 cm to 1.4 cm wide by 2 cm to 4 cm long (length measured from the lowest point of primary vein divergence to lobe apex). Secondary venation craspedodromous; secondary veins thick, 5 to 7 pairs per lobe, subopposite to alternate, course straight, extending directly to teeth apex without branching; angle of divergence uniform, moderate acute (45 to 60 ); secondary veins slightly decurrent on the primary veins; secondary veins extend to and fork at the major sinuses between the lobes. Tertiary veins moderate relative to secondary veins,

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66 percurrent, course straight; primary-tertiary vein angle oblique and constant; arrangement of tertiary veins predominately alternate (joining each other with an offset). Quaternary veins thin, course orthogonal (arising at right angles), transverse to tertiary veins. Conspicuous marginal veins present. In tooth sinus, tertiary veins fork and branches join with marginal veins before terminating at glandular tooth apex; three veins merge at the tooth apex, consisting of one secondary vein and two marginal veins. No veins of higher order observed. Number of specimens examined. 1. Holotype. UF15709-11883, 11883' (part and counterpart). Derivation of epithet. Latin, “quinque” means “five,” “lobus” means “lobe,” referring to the five lobed leaf. Discussion. The genus Dischidus was proposed by Schwarzwalder (1986, Ph. D thesis. See p.58 for generic diagnosis.) for fossil platanoid leaves previously assigned to the modern genus Aralia (primarily five lobed leaves). The five lobed stipulate leaf, tooth with thick glandular thickenings (possibly hydathodes), palinactinodromous primary venation and conspicuous marginal veins of the new species is clearly distinct from any previously described Cretaceous leav es from North America. These characters and the typical platanoid tooth type (three ve ins merging at the tooth apex, consisting one secondary vein and two marginal veins) indicate its relationship with the Platanaceae. Eoplatanus Schwarzwalder and Dilcher 1986 Eoplatanus serrata Schwarzwalder and Dilcher 1986 (Figure 13, 1-10; Figure 14, 1-7; Figure 15, 1; Figure 15, 2; Figure 15, 6; Figure 16, 1-15)

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67 Eoplatanus serrata Schwarzwalder and Dilcher 1986, , pl.8, Figures 35-37 (unpublished Ph.D. thesis). Specific diagnosis and Description. See Schwarzwalder (1986, Ph. D thesis, pp. 45-50) Number of specimens examined. 718. Discussion. About 480 specimens of leaves and 238 specimens of infructescences from the BraunÂ’s Ranch Locality, a 400 square-meter clay pit in Cloud County, Kansas, USA. Based on their co-occurrence, Wang et al. (2000) suggested that they are isolated organs of one plant species. The leaves are typically three lobed (Figure 13, 2; Figure 13, 3-4; Figure 13, 8; Figure 14, 1-5) with suprabasal actinodromous venation (Figure 13, 2; Figure 14, 1). Secondary venation is dominantly craspedodromous. Typically one secondary vein extends into each tooth and is accompanied by higher order veins (typically tertiary in order) that form a series of ascending loops. Glandular heads (hydathodes) are more distinctive on young leaves (Figure 13, 3; Figure 16, 15). Tertiary veins are percurrent (Figure 14, 2), with those in the axils of primary-primary and primary-secondary veins forming chevrons (Figure 14, 6-7). Conically inflated petiole bases are hollow and apparently enclose the axillary buds (Figure 13, 2; Figure 13, 6), which is a characteristic feature in all modern species of Platanaceae except in pinnately veined species Platanus kerrii (Leroy, 1982). Stipules (Figure 13, 6) are triangular in shape, small and only observed on immature leaves. Infructescences (Figure 16, 1-14) may contain up to 23 (Figure 16,4) globose heads. Fruits are achenes lacking a basal tuft of trichomes (dispersal hairs, Figure 16, 2-3), which is present in modern species. Achenes are small, 1.5 mm long by 0.5 mm wide,

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68 with a rounded apex and acute base (Figure 16, 2-3). Based on these observations, these specimens represent an extinct genus of Platanaceae (sycamore or plane tree family) (Wang et al., 2000). Paratypes. UF15709-3120; 3946; 4511; 4529; 11885; 11998; 23268; 23346; 23355; 31176; 31211; 39511. Aspidiophyllum Schwarzwalder and Dilcher 1986 Aspidiophyllum denticulatus Hongshan Wang sp. nov. (Figure 15, 3-5) Specific diagnosis. Leaf simple, trilobed. Leaf symmetrical; base symmetrical, margin toothed with round sinus, axes of serrations inclined to the tangent of the margin; apical angle of tooth acute, serration type convex-convex; teeth simple or occasionally compound; spacing regular, extent on almost entire margin except extreme base of leaf lamina; marginal glands at tooth apex as glandular thickenings. Primary venation palinactinodromous; primary veins massive, multistranded, course straight; position of primary veins. Secondary venation craspedodromous; secondary veins thick, subopposite to alternate, course straight, extending directly to teeth apex; angle of divergence uniform, moderate acute; secondary veins slightly decurrent on the primary veins; secondary veins extend to and fork at the major sinuses between the lobes; lowermost three or four secondary veins of lateral lobes always having exmedial and/or admedial branches which also extend directly into marginal teeth apexes. Tertiary veins moderate relative to secondary veins, percurrent, course straight; primary vein-tertiary vein angle oblique and decreases upward; arrangement of tertiary veins predominately. Quaternary veins thin, course percurrent, transverse to tertiary veins. Typically three veins

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69 terminating at the tooth apex, consisting of one secondary vein (or branches of secondary veins) and two marginal veins. Quinternary veins orthogonal. Description. Leaf simple, trilobed. Leaf symmetrical; base symmetrical, L/W 0.5, margin toothed with round sinus, axes of serrations inclined to the tangent of the margin; apical angle of tooth acute, serration type convex (basal side)-convex (apical side); teeth simple (of the same size) or occasionally compound (secondary teeth present); spacing regular, extent on almost entire margin except extreme base of leaf lamina; marginal glands at tooth apex as glandular thickenings, about 0.5 mm in diameter; observed petiole incomplete, 2 mm wide by 3 mm long. Primary venation palinactinodromous (primary veins having two lateral subsidiary points of radiation above the lowest point); primary veins massive, multistranded, course straight; position of primary veins perfect (lateral primary veins cover more than 2/3 of lamina). Secondary venation craspedodromous; secondary veins thick, 5 to 7 pairs per lobe, subopposite to alternate, course straight, extending directly to teeth apex; angle of divergence uniform, moderate acute (45 to 60 ); secondary veins slightly decurrent on the primary veins; secondary veins extend to and fork at the major sinuses between the lobes; lowermost three or four secondary veins of lateral lobes always having exmedial and admedial branches which also extend directly into marginal teeth apexes. Tertiary veins moderate relative to secondary veins, percurrent, course straight; primary-tertiary vein angle oblique and decreases upward; arrangement of tertiary veins predominately alternate (joining each other with an offset). Quaternary veins thin, course percurrent, transverse to tertiary veins. Typically three veins merge at the tooth apex, consisting of

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70 one secondary vein (or one branch of secondary veins) and two marginal veins. Quinternary veins orthogonal. Higher order veins not observed. Number of specimens examined. 2. Holotype. UF15709-23279. Paratype. UF15709-31177. Derivation of epithet. Latin, “denticulatus” means “with small teeth,” refers to many small teeth on leaf margin. Discussion. This species distinguishes from other Aspidiophyllum species by its numerous teeth on the leaf margin and its secondary veins possessing exmedial and admedial branches, which also extend directly into tooth apexes, and its percurrent tertiary and quaternary veins. It can be distinguished from other genera of platanoid leaves by its trilobed leaf shape. It differs from Eoplatanus serrata in that the secondary veins of Eoplatanus serrata don’t have exmedial and/or admedial branches, which also terminate in the teeth. Glandilunatus minnesotense Hongshan Wang sp. nov. (Figure 15, 7; Figure 29, 5) Specific diagnosis. See Courtland I locality I. Description. Leaf palmately lobed, estimated about 5 cm long by 4 cm wide, with 3 shallow lobes and the margins of each lobe repeatedly lobed; apex of lobes obtuse; conspicuous cresulent glands terminate on the lobes; base rounded; petiole not observed. Venation palinactinodromous; medial primary vein stout. Two major basal secondaries sub-opposite. Secondaries originating from primary vein at uniform (narrow acute) angles. Both exmedial and admedial branches from basal secondaries extending directly

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71 to major tooth apex, while these may giving rise to fine veins on both exmedial and admedial sides, but the finer veins terminate on the marginal gland base on secondary teeth on the sinuous. Tertiaries thin, angle of origin Acute-Acute (AA), course convex, originating at narrow acute angles on the exmedial side of the secondaries, extending into glands on the margin or the sinuous. Veins of higher order poorly preserved. Paratype. UF15709-11107. Discussion. Glandilunatus minnesotense is common at the Courtland I locality. Though only one specimen is observed from the BraunÂ’s Ranch Locality, it yields sufficient diagnostic characters such as palinactinodromous venation, cresulent glands on teeth, and all secondary veins and their branches terminate on the teeth to assign it to Glandilunatus minnesotense. Clade UNKNOWN Dicotylophyllum braunii Hongshan Wang sp. nov. (Figure 20, 5-6) Specific diagnosis. Petiole extremely abbreviated. Lamina trilobed; sinus between lobes more than 3/4 deep, symmetrical, lobes diverging at an angle of 90 . Form very wide ovate; base rounded; margin entire. Primary venation actinodromous; primary vein massive, course straight. Lobes oblong to narrow oblong; apex of middle lobe acuminate. Secondary veins thin, angle of divergence moderate acute (45 to 60 ). Secondary venation festooned brochidodromous; secondary veins uniformly curved, joining superadjacent secondary veins to form confluent loops near the margin, this forming a continuous vein which give rise to exmedial tertiary loops along the lamina margin. Intersecondary veins common, simple, 1 to 3 pairs per intercostal region.

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72 Description. Lamina trilobed; sinus between lobes more than 3/4 deep, symmetrical, lobes diverging at an angle of 90 . Form very wide ovate, L/W less than 1, at least 6 cm wide (distance between two lateral lobe apexes) by 4.2 cm long (middle lobe apex to point of primary vein divergence); base rounded; margin entire; petiole missing. Primary venation actinodromous three primary veins diverging radially almost from a single point form the lamina base; primary vein massive, course straight. Lobes oblong to narrow oblong; middle lobe 1.2 cm wide by 4.2 cm long (distance from apex to point of primary vein divergence); lateral lobes I cm wide by 3 cm long (observed length); apex of middle lobe acuminate, with a 3 mm long spinose apex. Secondary venation festooned brochidodromous; secondary veins thin, 5 to 6 pairs per lobe, angle of divergence moderate acute (45 to 60 ); secondary veins uniformly curved, joining superadjacent secondary veins to form confluent loops near the margin, forming a continuous vein which gives rise to tertiary exmedial loops along the margin of the lamina. Intersecondary veins common, simple, 1 to 3 pairs per intercostal region. Veins of higher order not observed. Lamina base slightly depressed. Number of specimens examined. 1. Holotype. UF15709-14841. Derivation of epithet. In honor of the Braun brothers for granting access to the claypit in their Ranch for collections. Discussion. The following diagnostic features distinguishes this species from all other Dakota Formation and modern angiosperm leaf species: trilobed lamina, entire lamina margin, actinodromous primary venation, festooned brochidodromous secondary venation with secondary veins uniformly curved and joining superadjacent secondary

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73 veins to form confluent loops near the margin, forming a continuous vein that gives rise to tertiary loops along the margin of the lamina, and intersecondary veins common. The depressed lamina base indicates that this specimen might represent a winged-fruit. The venation and disposition of the widely placed lateral lobes is reminiscent of the three lobed winged Juglandaceous fruits found in Eocene sediments (Dilcher et al., 1976). Dicotylophyllum fragilis Hongshan Wang sp. nov. (Figure 15, 8-9) Specific diagnosis. Leaf base peltate; petiole very thin, with many striations. Primary venation actinodromous; primary vein stout, curved in course, bifurcating gradually to give rise to secondary veins. Tertiary veins thin relative to primary or secondary veins; tertiary veins percurrent, angle of origin predominately acute-acute; course convex. Quaternary veins thin, arising from tertiary veins predominately at right angles. Description. Leaf apex missing; base peltate; observed petiole 6 cm long by 2 mm wide, appearing very thin, with may striations on petiole. Primary venation actinodromous (five primary veins diverging ra dially from a single suprabasal points), primary vein stout, curved in course, bifurcating gradually to give rise to (or integrate with) secondary veins. Tertiary veins thin relative to primary or secondary veins; angle of origin predominately acute-acute (AA) (angles of origin on the primary vein or exmedial side of secondary veins and on the admedial side of secondary veins acute); tertiary veins percurrent, course convex (middle portion of the vein curving away from the center of the leaf). Quaternary veins thin, arising from tertiary veins predominately at right angles. Veins of higher order not observed.

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74 Number of specimens examined. 1. Holotype. UF15709-30123. Derivation of Epithet. Latin, “fragilis” means “easily broken,” referring to the fragile character of this species. Discussion. This species differs from all other aquatic species from Hoisington III locality in having a thin lamina that is very easily broken during preservation, a long and thin petiole, peltate base, and thin higher order veins. The thin lamina structure, peltate leaf base, and its thin, striated long petiole indicate that this species may be an aquatic plant. Dicotylophyllum huangia Hongshan Wang sp. nov. (Figure 30, 5-6) Specific diagnosis. Leaf apex obtuse rounded. Leaf wide ovate. Margin toothed; serration axes inclined to the tangent of the margin; apical angle acute; serration type convex (basal side)-concave (apical si de); sinus rounded; teeth regularly spaced; teeth simple, extent more than 6/7 on distal margin; teeth contain glandular thickenings on tooth apex and may occasionally extend along basal side of teeth. Primary venation pinnate; primary vein moderate, course straight. Secondary venation semicraspedodromous; secondary veins moderate in thickness; course uniformly curved; intersecondary veins present, simple. Tertiary veins thick relative to secondary veins, randomly reticulate, occasionally percurrent; tertiary veins originated from exmedial branches of secondary veins extend into the tooth sinus. Quaternary veins moderate, reticulate, randomly oriented.

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75 Description. Leaf incomplete, apex obtuse rounded, base missing. Leaf wide ovate, L/W 1.2, 1.7 cm wide by 2 cm long. Margin toothed; serration axes inclined to the tangent of the margin; apical angle acute; serration type convex (basal side)-concave (apical side); sinus rounded; 5 to 6 teeth per cm, regularly spaced; teeth simple (all of one size), extent more than 6/7 on distal margin ; teeth contain glandular thickenings on tooth apex and may occasionally extend along basal side of teeth. Primary venation pinnate; primary veins thin, course straight. Secondary venation semicraspedodromous; secondary veins moderate, 5 pairs per lamina; angle of divergence moderate acute (45 to 65 ), variation uniform; course uniformly curved; intersecondary veins present, simple. Tertiary veins thick relative to secondary veins, randomly reticulate, occasionally percurrent; tertiary veins originated from exmedial branches of secondary veins extend into the tooth sinus. Quaternary veins moderate, reticulate, randomly oriented. Veins of higher order not observed. Number of specimens examined. 1. Holotype. UF15709-11845. Derivation of epithet. In honor of Qiangsheng C. Huang and in recognition of his contributions of the collections of Dakota Formation Angiosperm fossils. Discussion. This species is similar to Crassidenticulum landisae (Figure 27, 1-9; Figure 28, 1-5) in tooth type but they differ in that the latter has narrow elliptic to narrow oblong leaf shape, craspedodromous secondary venation, more secondary veins which originated from primary veins at more acute angles, composite intersecondary veins, and percurrent tertiary veins. Hickeyphyllum Hongshan Wang gen. nov.

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76 Generic diagnosis. Leaf narrow oblanceolate to elliptic, margin entire. Primary venation pinnate; primary vein multistranded. Secondary venation brochidodromous; intersecondary veins present. Tertiary veins moderate; random or orthogonal reticulate; quaternary veins thin, random reticulate. Derivation of generic name. In honor of Leo Hickey and in recognition of his contributions to angiosperm paleobotany. Discussion. The new genus, Hickeyphyllum is set up for those Dakota Formation fossil leaves with the following characters: narrow oblanceolate to elliptic shape with entire margin, primary venation pinnate, secondary venation brochidodromous, intersecondary veins common, and reticulate tertiary veins. Hickeyphyllum imhofia Hongshan Wang sp. nov. (Figure 19, 9-10) Specific diagnosis. Leaf coraceous, narrow oblanceolate; apex retuse; base decurrent, demarcation with petiole indistinct; petiole normal; margin entire, with strong marginal vein. Primary venation pinnate; primary veins massive, markedly curved, multistranded. Secondary venation festooned brochidodromous; secondary veins thin relative to primary vein; angle of divergence moderate acute; course abruptly curved, joining superadjacent secondary veins at acute or right angles to enclose prominent intercostal areas; secondary arches always enclosed by tertiary and quaternary arches; intersecondary veins present, composite. Tertiary veins moderate; random or orthogonal reticulate; quaternary veins thin, random reticul ate. Branches (quaternary or quinternary in order) from secondary or tertiary arches merge with marginal vein near leaf margin.

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77 Description. Leaf coraceous, narrow obvate to oblanceolate, L/W 5, lamina 6 cm long by 1.2 cm wide; apex retuse; base decurrent, demarcation with petiole indistinct; petiole normal; margin entire, with strong marginal vein. Primary venation pinnate; primary veins massive, markedly curved, multistranded. Secondary venation festooned brochidodromous (secondary veins joined together in a series of prominent arches); secondary veins thin relative to primary vein; angle of divergence moderate acute (45 to 65 ), with upper pairs more obtuse than lower ones; course abruptly curved, joining superadjacent secondary veins at acute or right angles to enclose prominent intercostal areas, intercostal areas near base more admedially oriented; secondary arches always enclosed by tertiary and quaternary arches; intersecondary veins present, composite. Tertiary veins moderate; random or orthogonal reticulate; quaternary veins thin, random reticulate. Veins of higher order not observed. Branches from secondary or tertiary arches (these veins are quaternary or quinternary in order) merge with marginal vein. Number of specimens examined. 1. Holotype. UF16709-16439; 16439Â’. Derivation of epithet. In honor of Stephan Imhof and in recognition of her contributions to the collection of specimens from the BraunÂ’s Ranch locality. Discussion. The following features: strong primary vein, prominent intercostal areas enclosed by secondary veins, composite intersecondary veins, strong marginal veins are diagnostic and can be used to distinguish it with other entire margined leaves from the Dakota Formation. Hickeyphyllum sandersia Hongshan Wang sp. nov. (Figure 19, 4-6)

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78 Specific diagnosis. Lamina narrow elliptic; apex mucronate; margin entire. Primary venation pinnate; primary vein stout, straight, multistranded. Secondary venation brochidodromous; secondary veins thin relative to primary vein, multistranded, arrangement on primary vein subopposite; secondary veins uniformly curved to join intersecondary vein and exmedial branches of secondary veins at obtuse angles to form a series of loops; these loops elongate, with long axes almost parallel to lamina margin; intersecondary veins common, simple, multistranded, extending to 2/3 distance from primary vein to leaf margin. Tertiary veins moderate, arising from secondary or intersecondary veins at irregular angles, course curved; orientation of tertiary veins almost parallel to long axis of lamina. Quaternary veins thin, randomly reticulate. Description. Lamina incomplete, slightly asymmetrical; lamina narrow elliptic, L/W > 4:1, lamina 3 cm long by 0.7 cm wide; apex mucronate; base missing; margin entire. Primary venation pinnate; primary vein stout, straight, multistranded. Secondary venation brochidodromous; secondary veins thick relative to primary vein, multistranded, about 8 pairs present, arrangement on primary vein subopposite; secondary veins uniformly curved to join intersecondary vein and exmedial branches of secondary veins at obtuse angles to form a series of loops; these loops elongate, almost parallel to the long axis of lamina; intersecondary veins common, simple, multistranded, extending to 2/3 distance from primary vein to leaf margin. Tertiary veins moderate, arising from secondary or intersecondary veins at irregular angles, course curved; orientation of tertiary veins almost parallel to leaf margin. Quaternary veins thin, randomly reticulate. Veins of higher order not observed. Number of specimens examined. 5.

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79 Holotype. UF15709-16487, 16487’. Other specimens examined UF15709-14843; 11112; 16459. Derivation of epithet. In honor of Ben Sanders and in recognition of his contributions to the collection of specimens from the Braun’s Ranch locality. Discussion. Hickeyphyllum sandersia differs from Hickeyphyllum imhofia in having narrow elliptic leaf shape, mucronate apex, secondary veins thick relative to primary vein, secondary loops elongate with long axes almost parallel to lamina margin, orientation of tertiary veins almost parallel to long axis of lamina (Table 3). Kladoneuron Hongshan Wang gen. nov. Generic diagnosis. Leaf margin entire. Primary venation pinnate. Secondary venation cladodromous; course of secondary veins uniformly curved, often fork once; branches from secondary veins may fork once or twice more near the margin; finer branches of these veins either join superadjacent branches to form loops or merge and then diminishing near the margin. Derivation of generic name. Greek, “klados” means “branch” and “neuron” means “nerve,” referring to the repeatedly branching veins. Discussion. The new genus Kladoneuron is set up for those fossil leaves from the Dakota Formation with cladodromous venation, which is a rare character on the leaves of the Cretaceous fossil angiosperms. Kladoneuron gooleria Hongshan Wang sp. nov. (Figure 23, 2-4) Specific diagnosis. Lamina oblanceolate, base decurrent; margin entire. Primary venation pinnate; primary vein stout. Secondary venation cladodromous; secondary

PAGE 88

80 veins thin relative to primary vein, 5 pairs per half lamina; angle of divergence narrow acute; course of secondary veins uniformly curved, often fork once at ¼ to ½ distance from primary vein to leaf margin; branches from secondary veins may fork once or twice more near the margin; finer branches of these veins either join superadjacent branches to form loops or merge and then diminishing near the margin. Description. Leaf slightly asymmetrical, oblanceolate, L/W 3:1, lamina 3.7 cm long by 1.2 cm wide; apex missing; base slightly asymmetrical, decurrent; petiole normal, short, 5 mm long by 1.2 mm wide; leaf margin entire. Primary venation pinnate; primary vein stout, slightly curved. Secondary venation cladodromous; secondary veins thin relative to primary vein, 5 pairs per half lamina; angle of divergence narrow acute (less than 45 ), upper pairs more obtuse than lower pairs; course of secondary veins uniformly curved, often fork once at ¼ to ½ distance from primary vein to leaf margin; branches from secondary veins may fork once or twice more near the margin; finer branches of these veins either join superadjacent branches to form loops or merge and then diminishing near the margin. Veins of higher order poorly preserved. Number of specimens examined. 1. Holotype. UF15709-12511, 12511’. Derivation of epithet. In honor of Scott Gooler and in recognition of his contributions to the collection of specimens of the Braun’s Ranch locality. Discussion. This species distinguish itself from all other entire margined leaves by its small leaf size, fewer secondary veins and cladodromous venation. Dicotylophyllum sp. (Figure 24, 4-6)

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81 Specific diagnosis. Leaf oblanceolate; apex obtuse; margin entire, structurally reinforced. Primary venation pinnate; primary vein stout, straight, multistranded. Secondary venation brochidodromous; secondary veins thin relative to primary vein, alternate; secondary veins decurrent on the primary vein, angle of divergence moderate acute; secondary veins appearing to be zigzag due to branching, joining exmedial branches of secondary vein near margin to form loops; differentiation of intercostal and excostal regions not obvious; intersecondary veins common, composite, integrading with tertiary veins. Tertiary veins randomly reticulate, integrading with intersecondary and quaternary veins. Quaternary veins thin, randomly reticulate, interlarding with tertiary veins. Veins of higher order not observed. Description. Leaf oblanceolate, L/W 3:1, lamina symmetrical, 6.5 cm long by 2.1 cm wide; apex obtuse; base possibly normal obtuse; petiole missing; margin entire, structurally reinforced. Primary venation pinnate; primary vein stout, straight, multistranded. Secondary venation brochidodromous; secondary veins thin relative to primary vein, about 12 secondary veins present, alternately arranged; secondary veins decurrent on the primary vein, angle of divergence moderate acute (about 45 ); secondary veins appearing to be zigzag due to branching, joining exmedial branches of secondary vein near margin to form loops; differentiation of intercostal and excostal regions not obvious; intersecondary veins common, 1 to 2 per intercostal region, composite, integrading with tertiary veins. Tertiary veins randomly reticulate, integrading with intersecondary and quaternary veins. Quaternary veins thin, randomly reticulate, integrading with tertiary veins. Veins of higher order not observed. Number of specimens examined. 2.

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82 Type. UF 15709-16505, 16505’; 11866. Discussion. This species differs from other Dakota Formation angiosperm species in having integrading intersecondary, tertiary, and quaternary veins; randomly reticulate venation; margins thinly reinforced. Hoisington III Locality, Kansas MAGNOLIIDS MAGNOLIALES Jarzenia Hongshan Wang gen. nov. Jarzenia kanbrasota Hongshan Wang sp. nov. (Figure 43, 6-7) “ Prunus” (?) parlatorii Lesquereux, 1868, Ann. Jour. Sci., 2nd ser., vol. 46, p.102. “ Andromeda” parlatorii Heer, Newberry, 1895, Flora of the Amboy clays, p.120, pl. 31, Figures 1-7; pl. 33, Figures 1,2,4,5. Description. Lamina elliptic, L/W 2.5, 3.5 to 4 cm wide by 9 to 10 cm long (estimated length). Apex missing. Base acute, decurrent. Margin entire. Petiole missing. Primary venation pinnate; primary vein stout, multistranded, course straight. Secondary venation brochidodromous; secondary vein moderate relative to primary vein. > 8 pairs per lamina, opposite to subopposite, decurrent; spacing irregular; angle of divergence narrow acute (< 45º), uniformly curved to join exmedial branches of superadjacent secondary veins to form one series of loops. Intersecondary veins present, course simple. Tertiary veins not well preserved, possibly percurrent. Number of specimens examined. 2. Paratypes. UF15706-3171; 24492. Discussion. See Courtland I locality systematics for discussion.

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83 LAURALES cf. LAURACEAE Wolfiophyllum Hongshan Wang gen. nov. Wolfiophyllum pfaffiana (Heer) Hongshan Wang comb. nov. (Figure 35, 7; Figure 44, 3-4) “ Andromeda” pfaffiana Heer, Lesquereux, 1874, Fl. Foss. Arct., vol.6, 2 Abth., p.79, pl.25, Figure 6; pl.38, Figures 5-7; pl.44, Figure 12). “ Andromeda” pfaffiana Lesquereux, 1892, pp.116-117, pl.18, Figures 7-8; pl.52, Figure 7. Specific diagnosis. Leaf simple; whole leaf lamina and base slightly asymmetrical; form very narrow elliptic. Base acute, decurrent. Margin entire. Petiole normal, short, stout. Primary venation pinnate; primary vein stout, multistranded, course straight. Secondary venation eucamptodromous, secondary veins upturned and gradually diminishing apically inside the margin, connected to the superadjacent secondary veins by a series of cross veins without forming prominent marginal loops. Angle of divergence of secondary veins uniform, narrow acute; secondary veins uniformly curved and gradually diminishing apically inside the margin, connected to the superadjacent secondary veins without forming prominent loops; intersecondary veins common, one per intercostal region, extending half to almost the same distance as adjacent secondary veins; intersecondary veins simple. Description. Leaf simple; whole leaf lamina and base symmetrical; form very narrow elliptic to narrow oblong, L/W 4 to > 7, 10 cm to 12 cm long (estimated maximum length) by 1.3 cm to 2.6 cm wide. Apex missing. Base acute, decurrent.

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84 Margin entire. Petiole normal, short, stout, up to 1 cm long by 1.5 mm wide, with decurrent lamina tissue on both sides, curved to one side. Primary venation pinnate; primary vein stout, multistranded, course strai ght or slightly curved. Secondary venation eucamptodromous, secondary veins upturned and gradually diminishing apically near the margin, connected to the superadjacent secondary veins by a series of cross veins without forming prominent marginal loops; secondary veins up to 12 pairs per lamina; angle of divergence uniform, narrow acute (less than 45 ); secondary veins uniformly curved and gradually diminishing apically inside the margin, connected to the superadjacent secondary veins without forming prominent loops; secondary vein course apically curved, occasionally forking near the margin; intersecondary veins common, one per intercostal region, extending half to almost the same distance as adjacent secondary veins; intersecondary veins simple. Tertiary veins predominately percurrent, course straight; angle of origin AO (acute on lower side of secondary veins and obtuse on upper side of secondary veins), forming cross veins between adjacent secondary and intersecondary veins. Veins of higher order poorly preserved. Number of specimens examined. 3. Holotype. UF15706-14815. Paratype. UF15706-24620. Other specimen examined . UF15706-4619. Discussion. The suite of characters, especially the combination of narrow elliptic simple leaf and eucamptodromous venation is different from any other angiosperm leaf megafossils from the Hoisington III locality, Kansas. The distinction between Wolfiophyllum pfaffiana with other similar leaves from Hoisington III locality is well

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85 demonstrated in Table 3. Wolfiophyllum pfaffiana is similar to Wolfiophyllum heigii from the BraunÂ’s Ranch Locality, Kansas, in that both are entire-margined leaves with eucamptodromous secondary venation, but they differ in that Wolfiophyllum heigii has thicker primary vein, stronger and fewer multistranded secondary veins, and seemingly thicker leaves. Wolfiophyllum pfaffiana is most similar in leaf architecture to some modern species in the Lauraceae with eucamptodromous secondary venation. For example, Phoebe angustifolia Meissn. (Klucking, 1987), Persea salicina (Hance) Kosterm. (Klucking, 1987), Lindera angustifolia Cheng and Lindera fragrans Oliv. vel. aff. (Klucking, 1987) all possess the same venation pattern and similar leaf shape. These modern species differ from the Wolfiophyllum pfaffiana in having relatively strong secondary veins, lacking intersecondary veins, and having well differentiated vein orders. Rogersia Fontaine 1889 Rogersia potteri Hongshan Wang sp. nov. (Figure 32, 2-3) Specific diagnosis. Leaf simple. Margin entire. Primary venation pinnate; primary vein stout, multistranded, course straight. Secondary venation festooned brochidodromous, spacing of secondary veins irregular, course uniformly curved; secondary veins joining exmedial branches of superadjacent secondary veins to form two series of loops. Intersecondary veins present, simple. Tertiary veins thin, predominately percurrent. Quaternary veins thin, orthogonal reticulate, anastomosing to form pentagonal or quadrangular meshes. Description. Leaf simple; whole leaf lamina and base symmetrical; form narrow elliptic, 7.5 cm long by 1.8 cm wide. Apex probably attenuate. Base acute, decurrent.

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86 Margin entire. Petiole normal, 1.1 cm long by 1mm wide. Primary venation pinnate; primary vein stout, multistranded, course straight. Secondary venation festooned brochidodromous; ±10 pairs per lamina, opposite or subopposite, decurrent; angle of divergence narrow acute (±30º), with lowest 2 to 3 pairs more acute than pairs above; spacing of secondary veins irregular, course uniformly curved; secondary veins joining exmedial branches of superadjacent secondary veins to form two series of loops. Intersecondary veins present, simple. Tertiary veins thin, predominately percurrent; angle of origin AO (acute on the lower side of the secondary and obtuse on the upper side), primary vein-tertiary vein angle oblique; course slightly wavy. Quaternary veins thin, orthogonal reticulate, anastomosing to form pentagonal or quadrangular meshes. Veins of higher order not observed. Number of specimens examined. 1. Holotype. UF15706-7529, 7529’. Derivation of epithet. In honor of Frank Potter and in recognition of his contributions to the collection of Hoisington III specimens from Kansas. Discussion. Rogersia potteri resembles other Dakota Formation entire margined leaves (Table 3), but it differs from them in having elliptic leaf shape, festooned brochidodromous secondary venation with well define intercostal region and two series of excostal loops, and percurrent tertiary veins. Rogersia kansense Hongshan Wang sp. nov. (Figure 35, 1-4; Figure 35, 6; Figure 35, 8) Specific diagnosis. Leaf simple; whole lamina and base symmetrical; form linear oblong. Apex attenuate. Base acute, decurrent. Margin entire. Petiole short, stout.

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87 Primary venation pinnate; primary vein stout, multistranded; course straight or slightly curved. Secondary venation brochidodromous; secondary veins thin relative to primary vein; subopposite, decurrent on primary vein; angle of divergence narrow acute (±30º), spacing irregular; secondary veins uniformly curved to join exmedial branches of super adjacent secondary veins or superadjacent secondary veins to form an intercostal region with its long axis oblique to primary vein (±30º), then continuing to join exmedial branches of adjacent secondary veins to form two series of loops; these loops enclosing elongate areas with long axis almost parallel to leaf margin; secondary veins running along the margin appearing to be intramarginal veins. Intersecondary veins present, simple. Tertiary veins thin, irregular, percurrent with retroflexed or straight course. Description. Leaf simple; whole lamina and base symmetrical; form linear oblong, L/W > 9, 7.5 cm to 9 cm long by 0.5 cm to 1 cm wide. Apex attenuate. Base acute, decurrent. Margin entire. Petiole short, stout. Primary venation pinnate; primary vein stout, multistranded; course straight or slightly curved. Secondary venation brochidodromous; secondary veins thin relative to primary vein, more than 10 pairs per leaf lamina; subopposite, decurrent on primary vein; angle of divergence narrow acute (±30º), spacing irregular; secondary veins uniformly curved to join exmedial branches of super adjacent secondary veins or superadjacent secondary veins at a distance of 1/5 to ¼ of half lamina to form an intercostal region with its long axis oblique primary vein (±30º), then continuing to join exmedial branches of adjacent secondary veins to form two series of loops; these loops enclosing elongate areas with long axis almost parallel to leaf margin; secondary veins running along the margin appearing to be intramarginal veins. Intersecondary veins present, 1 per intercostal region, simple, extending about ½

PAGE 96

88 distance from primary vein to leaf margin and then intersect with upper adjacent secondary veins. Tertiary veins thin, irregular, percurrent with retroflexed or straight course. Veins of higher order not observed. Number of specimens examined. 200. Holotype. UF15706-3063, 3063Â’. Paratypes. UF15706-24591 (shoot); 24801; 24798. Derivation of epithet. Referring the occurrence of this species in Kansas. Discussion. Rogersia kansense is similar in leaf shape and angle of divergence of secondary veins to Wolfiophyllum heigii from the BraunÂ’s Ranch locality of Kansas, but they differ in that W. heigii has eucamptodromous secondary venation, forking secondary veins near margin, and percurrent or exmedially ramified tertiary veins (Table 3). MAGNOLIIDS cf. CHLORANTHACEAE Crassidenticulum Upchurch and Dilcher 1990 Crassidenticulum decurrens Upchurch and Dilcher 1990 (Figure 36, 5-6) Celastrophyllum decurrens Lesquereux, 1892, p.172, pl.36, Figure 1. Crassidenticulum decurrens Upchurch and Dilcher, 1990, pp.29, pl.3-4, text Figure 3. Paratypes. UF15706-24648; 24685, 24685Â’. Discussion. Only two fragmentary specimens observed from the Hoisington III locality. The venation pattern, tooth type, and other characters are consistent with that described by Upchurch and Dilcher (1990). Crassidenticulum variloba Hongshan Wang sp. nov.

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89 (Figure 34, 1; Figure 36, 1) Specific diagnosis. Leaf simple, deeply trilobate or five-lobed; lobe shape lanceolate; medial lobe base symmetrical while lateral lobe base strongly asymmetrical, usually with the outer sides of outer lobes (or lateral lobes on trilobate leaf) strongly decurrent; margin of lobes toothed except on the extreme base of lamina; axes of serrations inclined to the tangent of the margin, apical angle acute; serration type convex (basal side)-convex (apical side); sinus of tooth rounded; regularly spaced; teeth simple; sinus between lobes rounded, bracing accomplished by primary vein. Petiole thin. Primary venation of lobes pinnate; primary vein stout. Secondary venation pinnate. Description. Leaf simple, deeply trilobate or five-lobed; lobe shape lanceolate; medial lobe base symmetrical while lateral lobe base strongly asymmetrical, usually with the outer sides of outer lobes (or lateral lobes on trilobate leaf) strongly decurrent; margin of lobes toothed except on the extreme base of lamina; axes of serrations inclined to the tangent of the margin, apical angle acute; serration type convex (basal side)-convex (apical side); sinus of tooth rounded; 8 to 10 teeth per cm, regularly spaced; teeth simple (all of one size); sinus between lobes rounded, bracing accomplished by primary veins (lamina structure lacking or less than 0.5 mm wide on the sinus. Petiole thin, observed petiole 5 cm long by 0.5 mm wide. Primary venation of lobes pinnate; primary vein stout. Secondary venation pinnate; secondary veins thin. Veins of higher order not observed. Number of specimens examined. 2. Types. UF15706-24679, 24679Â’; 24684.

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90 Discussion. These two specimens, lacking details of venation pattern, are difficult to assign to any other species. The deeply lobed leaf appear to be compound, making it difficult to assign these specimens to Crassidenticulum trilobus, which is deeply lobed but still has lamina structures on sinus. The secondary veins of Crassidenticulum trilobus are stronger and their spacing is larger. These specimens may related to Sapindopsis bagleyae as evidenced by their compound-looking shape and apparently sessile “leaflets,” but the margin of their “leaflet” is toothed, and their primary and secondary veins are thinner. I temporarily assign these two specimens to a new species. Crassidenticulum trilobus Hongshan Wang sp. nov. (Figure 36, 2) Number of specimens examined from Hoisington III locality . 1. Paratypes. UF15706-24677, 24677’ (Part and counterpart). Discussion. This species is common in the Braun’s Ranch locality, Kansas. Though only one specimen was observed from Hoisington III locality, its characteristic massive multistranded primary vein and secondary venation pattern assure its assignment to Crassidenticulum trilobus . cf. Atherospermataceae, Gomortegaceae, Gyrocarpaceae, Lauraceae, Hernandiaceae, and Hortoniaceae Pabiania Upchurch and Dilcher 1990 Pabiania variloba Upchurch and Dilcher 1990 (Figure 33, 1-4; Figure 33, 6-7)

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91 Pabiania variloba Upchurch and Dilcher, 1990, Plate 8; plate 9, Figures 1-3; plate 11, Figures 1-7; text Figures 8-9. Acerites multiformis Lesquereux, Retallack and Dilcher, 1981, Figure 4. Specific diagnosis and Description. (See Upchurch and Dilcher, 1990, pp.2126). Number of specimens examined from Hoisington III locality . 56. Paratypes. UF15706-14812; 14832; 24436; 24483; 24587; 24653. Discussion. In Upchurch and Dilcher’s (1990) diagnosis and description of this species, the primary venation was described as palinactinodromous. Observations based on Hoisington III locality specimens indicate that the primary venation of P. variloba is suprabasal actinodromous. Of the published specimens by Upchurch and Dilcher (1990) and specimens stored at the Paleobotany collection in the Florida Museum of Natural History (50 specimens), most of the leaves are smaller in size compared with the specimens from the Hoisington III locality, Kansas. All other characters are consistent with those described by Upchurch and Dilcher (1990). One specimen (Upchurch and Dilcher, 1990) has basal actinodromous venation instead of suprabasal actinodromous venation. This specimen was assigned to Pabiania groenlandica (Heer) Wang. Pabiania groenlandica (Heer) Hongshan Wang comb. nov. (Figure 31, 1-7) “Aralia” groenlandica Heer, 1882, Heer, p.84, pl.38, Figure 3; pl.39, Figure 1; pl.46, Figures 16-17 “Aralia” groenlandica Heer,1892, Lesquereux, pp.134-135, pl.54, Figures 1-3. Pabiania variloba Upchurch and Dilcher, 1990, pl.8, Figure 6.

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92 Specific diagnosis. Leaf trilobate. Base rounded. Petiole long, commonly with winged lamina tissue along both sides of the margin, base of petiole ocreate. Margin entire. Apex of lobes rounded. Lateral lobes or iented at wide angles with medial lobe. Primary venation basal actinodromous, occasionally suprabasal actinodromous if basilaminar secondary veins strongly developed; medial primary vein stout, lateral primary veins of the same thickness, all extending directly to the apex of lobes; medial primary vein course straight or slightly curved; lateral primary veins course recurved, diverging from medial primary veins at slightly lower angles than superadjacent secondary veins. Secondary venation festooned brochidodromous; secondary veins moderate in thickness relative to primary veins; two pairs of basilaminar secondary veins present in all leaves (with one strongly developed and secondary in order and the other pair tertiary in order); secondary veins opposite, diverging from medial primary vein at wide angle, looping festooned brochidodromous, t ypically two series of loops present in the excostal region; two secondary veins (one form medial primary vein and one from admedial side of lateral primary veins) joining below the sinus to brace the sinus; angle of brochidodromous junction obtuse; excostal loops curving apically. Intersecondary veins common, simple or composite, extending at ½ of half lobe lamina. Tertiary veins thin relative to secondary veins, predominately randomly reticulate. Quaternary veins random reticulate. Veins of secondary or tertiary order below sinus and between medial and lateral primary veins form inverted 'V's. Description. Leaf trilobate. Base rounded. Petiole long, up to 5 cm long by ±1 mm wide, commonly with winged lamina tissue along both sides of the margin, base of petiole ocreate (with an ocrea-like structure). Margin entire. Apex of lobes rounded;

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93 lamina L/W less than 1 (length measured from the leaf base to apex of medial lobe and width measured from widest portion of late ral lobes perpendicular to medial primary vein), leaf up to 13.5 cm long by at least 15 cm wide. Lateral lobes oriented at wide angles with medial lobe. Primary venation basal actinodromous, occasionally suprabasal actinodromous if basilaminar secondary veins strongly developed (three pairs present); medial primary vein stout, lateral primary veins of the same thickness, all extending directly to the apex of lobes; medial primary vein course straight or slightly curved; lateral primary veins course recurved, diverging from medial primary vein at slightly lower angles than superadjacent secondary veins. Secondary venation festooned brochidodromous; secondary veins moderate in thickness relative to primary veins, 2 to 4 pairs, typically 3 in each lobe; two pairs of basilaminar secondary veins present in all leaves (with one strongly developed and secondary in order and the other pair tertiary in order); secondary veins opposite, diverging from medial primary vein at wide angle (70º to 90º), looping festooned brochidodromous, typica lly two series of loops present in the excostal region; two secondary veins (one form medial primary vein and one from admedial side of lateral primary veins) joining below the sinus to brace the sinus; angle of brochidodromous junction obtuse; excostal loops curving apically. Intersecondary veins common, simple or composite, extending at ½ of half lobe lamina. Tertiary veins thin relative to secondary veins, predominately randomly reticulate. Quaternary veins random reticulate. Veins of secondary or tertiary order below sinus and between medial and lateral primary veins form inverted 'V's. Veins of higher order not observed. Number of specimens examined. 34. Holotype. UF15706-24464.

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94 Paratypes. UF15706-14823; 24414; 30154, 30154Â’; 24423. Discussion. Pabiania groenlandica is similar to Pabiania variloba Upchurch and Dilcher in that both are trilobed. It differs from Pabiania variloba in having a more rounded lobe apex and leaf base, long petiole with winged lamina tissue along both sides and with ocreate base, lateral lobes oriented at wide angles to medial lobe, primary venation basal actinodromous, both medial and lateral primary veins stout and extending directly to the apex of lobes, secondary venation festooned brochidodromous, and a common intersecondary vein. One specimen published by Upchurch and Dilcher (1990) has basal actinodromous venation instead of suprabasal actinodromous venation. This specimen indicates the occurrence of P. groenlandica at Rose Creek I locality, Nebraska. Pabiania cf. P. groenlandica (Heer) Hongshan Wang comb. nov. (Figure 33, 5) Specific diagnosis. Leaf trilobate. Base rounded. Apex of lobes rounded. Lateral lobes oriented at wide angles with medial lobe. Primary venation basal actinodromous; medial primary vein stout, lateral primary veins of the same thickness, all extending directly to the apex of lobes; medial primary vein course slightly curved; lateral primary veins course strongly recurved, almost perpendicular to medial primary vein. Secondary venation festooned brochidodromous; secondary veins moderate in thickness relative to primary veins; secondary veins opposite, diverging from medial primary vein at wide angle, looping festoone d brochidodromous, typically two series of loops present in the excostal region; two secondary veins (one form medial primary vein and one from admedial side of lateral primary veins) joining below the sinus to brace the sinus; angle of brochidodromous junction obt use; excostal loops curving apically;

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95 exmedial branches from lateral primary veins strongly developed. Intersecondary veins common, simple or composite, extending at ½ of half lobe lamina. Description. Leaf trilobate. Base rounded. Petiole not observed. Margin entire. Apex of lobes rounded; lamina L/W < 1, leaf up to 13.5 cm long by at least 20 cm wide (estimated maximum width). Lateral lobes orie nted at wide angles with medial lobe. Primary venation basal actinodromous; medial primary vein stout, lateral primary veins of the same thickness, all extending directly to the apex of lobes; medial primary vein course straight or slightly curved; lateral primary veins course recurved, almost perpendicular to medial primary vein. Secondary venation festooned brochidodromous; secondary veins moderate in thickness, reticulate to primary veins, 2 to 4 pairs, typically 3 in each lobe; basilaminar secondary veins lacking; exmedial branched from lateral primary veins strongly developed; secondary veins opposite, diverging from medial primary vein at wide angle (70º to 90º ), looping festooned brochidodromous, typically two series of loops present in the excostal region; two secondary veins (one form medial primary vein and one from admedial side of lateral primary veins) joining below the sinus to brace the sinus; angle of brochidodromous junction obtuse; excostal loops curving apically. Intersecondary veins common, simple or composite, extending at ½ of half lobe lamina. Veins of higher order not observed. Number of specimens examined. 1. Holotype. UF15706-24465. Discussion. Most characters of this leaf type are the same as those of Pabiania groenlandica. It is different from Pabiania groenlandica in two characters, the large leaf size and the lack of two or more basilaminar secondary veins. Observations on more

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96 specimens are needed in order to justify segregation from Pabiania groenlandica as a new species. cf. Illiciaceae Longstrethia Upchurch and Dilcher 1990 Longstrethia aspera (Lesquereux) Hongshan Wang comb. nov. (Figure 44, 1-2; Figure 44, 5) “Myrica” aspera Lesquereux, 1892, p.66, pl.2, Figure 11. Specific diagnosis. Leaf margin toothed; serrate axes inclined to the tangent of margin, serration type straight or convex-st raight or convex; tooth simple, spacing irregular; sinus rounded; three veins entering each tooth with one medial secondary vein or branch from secondary vein, two accompanying veins from basal and apical side, these two veins joining superadjacent veins of the same order to form loops before entering tooth. Primary venation pinnate; primary vein stout, multistranded, course curved. Secondary venation mixed craspedodromous; secondary veins thin relative to primary vein, subopposite; originating from primary vein at moderate acute angles, uniformly apically curved before entering the tooth or running along the basal side of tooth before terminating on the tooth with superadjacent secondary veins. Intersecondary veins present, composite. Tertiary veins thin, orthogonal reticulate, forming meshes irregular in shape and size. Quaternary vein orthogonal reticulate, forming imperfect areoles. Veinlets simple, linear or curved. Description. Two specimens of middle portion of leaf lamina observed. Observed lamina 9 cm to 15 cm long by 1.5 cm to 2.5 cm wide. Margin toothed; serrate axes inclined to the tangent of margin, serration type straight or convex-straight or

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97 convex; tooth simple, spacing irregular, one per cm; extending on all margin observed; sinus rounded, up to 1.5 mm deep (vertical distance from adjacent tooth apex to bottom of sinus); three veins entering each tooth with one medial secondary vein or branch from secondary vein, two accompanying veins from basal and apical side, these two veins joining superadjacent veins of same order to form loops before entering tooth. Primary venation pinnate; primary vein stout, multistranded, course curved. Secondary venation mixed craspedodromous (most of the secondary veins terminating at the margin and the rest brochidodromous); secondary veins thin relative to primary vein, one pair per cm, subopposite; originating from primary vein at moderate acute angles, uniformly apically curved before entering the tooth or running along the basal side of tooth before terminating on the tooth with superadjacent secondary veins. Intersecondary veins present, composite. Tertiary veins thin, orthogonal reticulate, forming meshes irregular in shape and size. Quaternary vein orthogonal reticulate, forming imperfect areoles. Veinlets simple, linear or curved. Number of specimens examined. 2. Holotype. Longstrethia aspera Lesquereux, 1892, p.66, pl.2, Figure 11. Paratypes. UF15706-24578; 24650, 24650’. Discussion. Longstrethia aspera is similar to “Quercus” primordialis Lesquereux (1868, 1874) in leaf shape and toothed margin, and craspedodromous secondary venation, but they differ in that “Quercus” primordialis has more secondary veins which are closely arranged, and percurrent tertiary veins. Longstrethia aspera is similar to Longstrethia varidentata Upchurch and Dilcher (Upchurch and Dilcher, 1990) in that both have linear leaf shape and toothed margin, but they differ in that (1) leaf

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98 margin of Longstrethia varidentata varies from entire to coarsely toothed, (2) secondary venation varies from brochidodromous with strongly flattened brochidodromous loops, to pinnate with an intramarginal vein, and (3) relatively thin and numerous secondary veins. For modern affinities of this genus, see Upchurch and Dilcher (1990). PROTEALES aff. PLATANACEAE Credneria Schwarzwalder and Dilcher 1986 Credneria cyclophylla (Heer) Hongshan Wang comb. nov. (Figure 34, 4; Figure 34, 6-7) Specific diagnosis. Leaf very wide ovate. Base obtuse, decurrent. Margin toothed; tooth simple, extending on upper 2/ 3 margin, spacing irregular; dentate axes approximately perpendicular to the tangent of the margin; dentate apex obtuse, mucronate; toothed type concave on both sides; sinus rounded, shallow. Primary venation pinnate; primary vein stout, multistranded, course straight. Secondary venation simple craspedodromous; secondary veins thick relative to primary veins, multistranded, opposite or subopposite; angle of divergence narrow acute; secondary vein course straight or slightly curved, all terminating on the margin; 2 to 3 exmedial branches from basal two pairs of secondary veins also terminating on the margin. Intersecondary veins absent. Tertiary veins thick, percurrent, course convex; angle of origin AA (acute on both sides of secondary veins); arrangement on secondary veins close. Quaternary veins percurrent, course straight; quinternary veins orthogonal reticulate, forming quadrangular well-developed areoles. Veinlets simple, linear or curved.

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99 Description. Whole lamina and base symmetrical, very wide ovate, L/W < 1, 8 cm long (estimated length) by 8.5 cm wide. Apex missing. Base obtuse, decurrent. Margin toothed; tooth simple, extending on upper 2/3 margin, spacing irregular, 2 to 3 teeth per cm on middle portion of margin; dentate axes approximately perpendicular to the tangent of the margin; dentate apex obtuse (> 90º), mucronate; toothed type concave on both sides; sinus rounded, shallow (less than 1 mm deep-vertical distance from tooth apex to bottom of sinus). Observed petiole 3 cm long by 1 mm wide. Primary venation pinnate; primary vein stout, multistranded, course straight. Secondary venation simple craspedodromous (all of the secondary veins and their branches terminating at the margin); secondary veins thick relative to primary veins, multistranded, ±5 pairs per leaf lamina, opposite or subopposite; angle of divergence narrow acute (< 45º) with uniform variation; secondary vein course straight or slightly curved, all terminating at the margin; 2 to 3 exmedial branches from basal two pairs of secondary veins also terminating on the margin. Intersecondary vein absent. Tertiary veins thick, percurrent, course convex (middle portion of vein curve away from the cen ter of the leaf); angle of origin AA (acute on both sides of secondary veins); arrangement on secondary veins close (interval between veins less than 0.5 cm). Quaternary veins percurrent (perpendicular to tertiary veins), course straight; quinternary vein s orthogonal reticulate, forming quadrangular well-developed areoles. Veinlets simple, linear or curved. Number of specimens examined. 3. Holotype. “Populus” cyclophylla Heer, 1858, Proc. Phila. Acad. Nat. Sci., p. 266. Paratypes. UF15706-24780; 24783; 14821.

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100 Discussion. The specimens from Hoisington III locality are less variable in leaf shape, but they demonstrate well-preserved higher order veins, especially ultimate veins. Other characters are consistent with those from the Courtland I locality. cf. PLATANACEAE Sapindopsis Fontaine 1889 Sapindopsis bagleyae Hongshan Wang sp. nov. (Figure 40, 1-5; Figure 39, 1-7; Figure 41, 1-7) Specific diagnosis. Leaf compound, consisting of three to six pinnately alternate to opposite leaflets; leaf stipulate, petiole thin; leaflets narrow oblong to narrow elliptic; leaflet margin entire, structurally reinforced, apex acute to acuminate, base acute and asymmetrical, when four leaflets present the terminal two leaflets decurrent on rachis; two ultimate leaflets oppositely arranged, with outer side lamina decurrent on rachis, giving a bilobed appearance; the apex of thes e two leaflets sometimes lobed once, with deep sinus extending about 1/3 distance of lamina length, bracing of the sinus accomplished by forking of primary veins and then running along the margin within sinus. Leaflet occasionally sessile or with thin petiole. Primary venation of leaflets pinnate; primary vein multistranded, stout to massive, course straight. Secondary venation eucamptodromous or slightly brochidodromous; secondary veins moderate in thickness, numerous; secondary veins uniformly originate from primary vein at moderate to narrow acute, subopposite, uniformly curved and diminish near lamina margin; intersecondary veins common, composite. Tertiary veins thick relative to secondary veins, angle of origin acute-obtuse, predominately percurrent, slightly convex;

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101 arrangement on secondary vein predominately alternate. Quaternary veins orthogonal, forming quadrangular or pentagona l imperfect areoles; veinlets simple, curved or straight. Description. Leaf compound, consisting of three to six pinnately arranged alternate (Figure 39, 7) to opposite (Figure 39, 1; Figure 39, 5) leaflets; leaf stipulate (Figure 40, 3; Figure 39, 1; Figure 41, 1-2), pe tiole thin, stipules up to 1.5 cm long by 0.6 cm wide, with venation parallel to the long axis; leaflets narrow oblong (Figure 41, 7) to narrow elliptic (Figure 39, 1); leaflet 6.5 cm to 13.5 cm long by 1.5 cm to 2.5 cm wide (L/W 4.3 to 5.4); leaflet margins entire, structurally reinforced, apex acute to acuminate, base acute and asymmetrical, when four leaflets present the terminal two leaflets decurrent on rachis; two ultimate leaflets oppositely arranged, with outer sides lamina decurrent on rachis, giving a bilobed appearance; the apex of these two leaflets sometimes lobed once, with deep sinus extending about 30% distance of lamina length, bracing of the sinus accomplished by forking of primary veins and then running along the margin within sinus. Leaflet occasionally sess ile or with thin petiolule, about 1 mm wide and up to 3.5 cm long. Primary venation of leaflets pinnate; primary vein multistranded, stout to massive (the ratio of vein width to lamina width is ± 4%), course straight. Secondary venation eucamptodromous (secondary veins upturned and gradually diminishing apically inside the margin, connected to the superadjacent secondary veins by a series of cross veins without forming prominent marginal loops) or slightly brochidodromous; secondary veins moderate in thickness, ± 15 pairs per leaflet lamina; secondary veins uniformly originate from primary vein at moderate to narrow acute (less than 65 ) angle, up to 15 pairs per leaflet, subopposite, uniformly curved and diminish near lamina margin; intersecondary veins common, composite (made up of coalesced

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102 tertiary vein segments for over 50% of its length). Tertiary veins thick relative to secondary veins, angle of origin acute-obtuse (AO, lower side of the secondary vein and upper side of the secondary veins), predominately percurrent, slightly convex; arrangement on secondary vein predominately alternate. Quaternary veins orthogonal (arising at right angles), forming quadrangular or pentagonal imperfect areoles; veinlets simple, curved or straight. Number of specimens examined. 110. Holotype. UF15706-14830, 14830Â’. Paratypes. UF15706-4812; 14814; 14831; 24481; 24670; 24681, 24681Â’; 24675; 24683, 24683Â’; 24711; 24719; 24747; 24758; 31455. Derivation of epithet. In honor of Carolyn Bagley and in recognition of her contributions to the collections of Hoisington III locality specimens. Discussion. Sapindopsis bagleyae differs from Sapindopsis anhouryi Dilcher and Basson (Dilcher and Basson, 1990) from the mid-Cretaceous locality of Lebanon in having compound leaves consisting of three to six pinnately alternate to opposite leaflets, leaflets narrow oblong to narrow elliptic and with distinctive petioles, eucamptodromous or slightly brochidodromous secondary venation, and percurrent tertiaries. Compared with other species of Sapindopsis from the Potomac Group (Hickey and Doyle, 1977), Sapindopsis bagleyae has high differentiation venation orders. Sapindopsis bagleyae differs from Sapindopsis variabilis of the Cheyenne Group (Huang, 1989; Huang and Dilcher, 1994) in that Sapindopsis variabilis is characterized by winged petiolules and variably sized leaflets. Sapindopsis bagleyae from Sapindopsis sp. A of the Cheyenne Group (Huang, 1989; Huang and Dilcher, 1994) in that Sapindopsis sp. A has only three

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103 leaflets. Sapindopsis bagleyae differs from Sapindopsis sp. B of the Cheyenne Group (Huang, 1989; Huang and Dilcher, 1994) in that Sapindopsis sp. B has truly pinnate, compound leaves, while the ultimate leaflets of Sapindopsis bagleyae may be sessile. For discussion on modern affinities of the genus Sapindopsis , see Doyle and Hickey (1976) and Upchurch et al. (1994). Sapindopsis retallackii Hongshan Wang sp. nov. (Figure 36, 3-4) Description. Lamina base symmetrical. Form lanceolate, L/W > 5, 10 cm long (estimated length) by 1.8 cm wide. Apex missing. Base normal, acute. Margin entire. Petiole normal, short, 0.8 cm long by 0.5 mm wide. Primary venation pinnate; primary vein stout, slightly curved, up to 0.5 mm wide at the widest portion of leaf lamina. Secondary venation festooned brochidodromous; secondary vein fine relative to primary vein; secondary veins diverging from primary vein at narrow acute angles, with lowest 1 to 2 pairs more acute than pairs above; secondary veins slightly recurved after diverging from primary vein, then extending a distance to about ½ to ¼ of half lamina before joining superadjacent secondary or intersecondary veins to form two series of loops in the excostal region. Intersecondary veins common, 1 to 3 pairs per intercostal region; intersecondary veins simple or occasionally forking at variable distance after diverging from primary vein; intersecondary veins almost the same width as secondary veins. Tertiary veins hair like; diverging from primary veins, exmedial (lower) side of secondary veins or intersecondary veins at moderate acute to narrow acute angles, predominately exmedially ramified, orientation parallel to secondary or intersecondary veins, connected by cross veins of the same order.

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104 Number of specimens examined. 1. Paratype. UF15706-3153. Discussion. Only one specimen was observed from Hoisington III locality but the distinctive venation pattern shows that it represents a leaflet of Sapindopsis retallackii Sapindopsis beekeria Hongshan Wang sp. nov. (Figure 35, 5; Figure 42, 1; Figure 42, 4) Specific diagnosis. Leaf pinnate compound; leaflets alternately arranged on rachis; leaflet elliptic; leaflet base, asymmetrical, apex acute, margin entire, petiole short. Primary venation pinnate; primary vein stout, multistranded, course straight. Secondary vein course straight, opposite to subopposite; spacing irregular, densely arranged; angle of divergence wide acute, with basal pairs slightly obtuse than pairs above; secondary veins course straight, curved abruptly very close to margin to form intramarginal vein; Intersecondary veins common, simple. Description. Leaf pinnate compound; leaflets alternately arranged on rachis; leaflet elliptic, L/W 2.5, lamina 1.8 cm to 4.1 cm wide by 4.5 cm to 10 cm long; leaflet base acute or obtuse decurrent, asymmetrical, apex acute, margin entire, petiole short. Primary venation pinnate; primary vein stout, multistranded, course straight. Secondary venation not well observed, possibly forming an intramarginal vein very close to margin; secondary veins moderate relative to primary veins; more than 15 pairs per lamina, course straight, opposite to subopposite; spacing irregular, densely arranged; angle of divergence wide acute (> 60º), with basal pairs slightly obtuse than pairs above; secondary veins course straight, curved abruptly very close to margin to form intramarginal vein; intersecondary veins common, 1 to 2 per intercostal region, simple,

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105 course parallel to adjacent secondary veins, extending 4/5 distance from primary vein to lamina margin. Veins of higher order not observed. Number of specimens examined. 3. Types. UF15706-14813; 12922; 24568. Derivation of epithet. In honor of Charles Beeker and in recognition of his contributions to the collection of Dakota Formation specimens. Discussion. Densely arranged secondary and intersecondary veins, a possible intramarginal vein, and alternate arrangement of leaflets on rachis are diagnostic of this species. This suite of characters can be used to distinguish Sapindopsis beekeria from other members of the Sapindopsis. Clade UNKNOWN Skogia Hongshan Wang gen. nov. Generic diagnosis. Lamina thin. Base cordate. Margin entire. Petioles thin, multistranded. Primary venation pinnate; primary vein multistranded. Secondary vein thin, decurrent on primary vein, subopposite; angle of divergence moderate acute uniform. Intersecondary veins common, simple. Tertiary veins thin, originating from secondary or intersecondary veins at right angles, forming meshes rectangular or square in shape and oriented with long axis parallel to secondary veins. Quaternary veins of the same pattern. Derivation of generic name. In honor of Judith Skog and in recognition of her contributions to paleobotanical research. Skogia leptoselis Hongshan Wang sp. nov. (Figure 44, 6-7)

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106 Specific diagnosis. Same as for genus. Description. Observed lamina 11 cm long by 5 cm wide; lamina very thin. Base cordate. Observed margin entire. Petiole thin, multistranded, 6 cm long by 1.5 mm wide. Primary venation pinnate; observed primary vein 1.5 mm wide, multistranded, slightly curved. Secondary venation not observed; secondary vein thin relative to primary vein, 8 pairs observed, decurrent on primary vein, subopposite; angle of divergence moderate acute (±45º), uniform. Intersecondary veins common, simple, 1 to 2 pairs between two adjacent secondary veins. Tertiary veins thin, originating from secondary or intersecondary veins at right angles, forming meshes rectangular or square in shape and oriented with long axis parallel to secondary veins. Quaternary veins of the same pattern. Veins of higher order not observed. Number of specimens examined. 1. Holotype. UF15706-24573. Derivation of epithet. Greek, “lepto” means “thin, delicate” and “selis” means “leaf,” referring to the thin and delicate lamina structure. Discussion. The observed leaf lamina is 11 cm long and estimated leaf length may be up to at least 15 cm. Although secondary venation pattern is not observed because the fragmented nature of the specime n, the combined feature of this leaf type, such as thin lamina structure, thin primary and higher order veins, large spacing of secondary veins (8 pairs observed on 11 cm lamina), the presence of intersecondary veins, and tertiary venation patterns is distinctive from any other Dakota Formation fossil angiosperms. The multistranded primary vein and the presence of intersecondary veins indicate its possible affinity within the Magnoliidae. The thin lamina texture, tertiary and

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107 quaternary veins forming rectangular meshes with long axis parallel to secondary veins are observed in some extant herbaceous angiosperms, and this may indicate Skogia leptoselis is an herbaceous plant which grows near water. PROTEALES aff. NELUMBONACEAE Nelumbites Berry 1911 Nelumbites fluitus Hongshan Wang sp. nov. (Figure 45, 1-7; Figure 46, 1; Figure 46, 3-4; Figure 47, 2) Specific diagnosis. Leaf orbicular. Base strongly auriculate with auricles overlapping or wide. Petiole with a spheri cal floating structure attached at middle portion. Margin crenate; dentate obtuse, both sides convex; dentate simple, spacing regular, extending almost on complete margin; sinus rounded, shallow; typically three veins entering a tooth, one medial vein of tertiary order and perpendicular to the tangent of margin and two accompanying veins of quaternary order running along margin before entering tooth. Primary venation basal actinodromous; primary veins massive, typically one medial and 4 lateral primary veins on one leaf lamina; medial vein straight, terminating on the margin; lateral primary veins forking several times, gradually decreasing in thickness toward margin, joining adjacent branches to form five to sevensided meshes with long axes radially oriented; all lateral primary veins apically curved; exmedial branches of two outer lateral primary veins also apically curved. Veins of secondary order not obvious. Veins of higher order (tertiary or quaternary) within those primary-vein-formed meshes orthogonal reticulate, forming quadrangular or pentagonal smaller meshes; quinternary veins orthogonal reticulate, forming the smallest meshes.

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108 Description. Leaf orbicular, 1 to 4 cm in diameter. Base strongly auriculate or wide obtuse (a special case of obtuse such that the base angle is large than 180º, LAWG, 1999), auricles overlapping. Observed petiole 3 cm long by 1.5 mm wide, with a spherical floating structure att ached at middle portion. Margin cremate, with dentate axes approximately perpendicular to the tangent of the margin; dentate obtuse, both sides convex; dentate simple, spacing regular, ±5 per cm on margin, extending almost on complete margin; sinus rounded, shallow, no more than 0.5 mm deep (vertical distance from apex of adjacent dentate to bottom of sinus); typically three veins entering a tooth, one medial vein of tertiary order and perpendicular to the tangent of margin and two accompanying veins of quaternary order running along margin before entering tooth. Primary venation basal actinodromous; primary veins massive, typically one medial and 4 lateral primary veins on one leaf lamina; medial vein straight, terminating on the margin; lateral primary veins forking several times, gradually thinning toward margin, joining adjacent branches to form five to seven-sided meshes with long axes radially oriented; all lateral primary veins apically curved; exmedial branches of two outer lateral primary veins also apically curved. Veins of secondary order not obvious. Veins of higher order (tertiary or quaternary) within those meshes orthogonal reticulate, forming quadrangular or pentagonal smaller meshed; quinternary veins orthogonal reticulate, forming the smallest meshes. Number of specimens examined. 35. Holotype. UF15706-8263, 8263’. Types. UF15706-3075, 3075’; 3116; 8264; 8268; 24086; 24088; 24094; 24120; 24637.

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109 Derivation of Epithet. Latin, “fluito” means “float,” referring to that the species possesses floating structures. Discussion. This species differs from all other Dakota Formation aquatic angiosperm leaf megafossils in having a strongly auriculate leaf base, petiole with a spherical float attached, dentate margin, basal actinodromous venation with all lateral primary veins apically curved, primary veins forming five to seven-sided meshes with long axes radially oriented. Nelumbites fluitus resembles Nelumbites cf. N. minimus (Vakhrameev) Upchurch et al. (Upchurch et al., 1994) in small leaf size, orbicular leaf shape, and crenate margin but it differs from it in having auriculate leaf base, basal actinodromous primary venation, more primary veins and all distally oriented, and with a floating structure attached on the petiole (Table 5). The floating structures of Nelumbites fluitus resemble the pseudo-bulbs of Eichhornia crassipes (water hyacinth) of the Pontederiaceae. Eichhornia crassipes is a floating aquatic plant, native to tropical America. Its leaves are attached to inflated stems with trapped air, and act as an air bladder providing buoyancy, which enables the plants to float freely. The water hyacinth tends to grow in large bunches and lives in still or slow moving fresh water. However, the co-occurrence of Nelumbites fluitus with rhizome-like structures (Figure 46, 5) may indicate that Nelumbites fluitus leaves are attached to these rhizome-like structures and are not freely floating. Nelumbites crassinervum Hongshan Wang sp. nov. (Figure 46, 2; Figure 47, 1; 47, 3-6) Specific diagnosis. Leaf orbicular. Base peltate eccentric. Margin crenate; dentate axes approximately perpendicular to the tangent of margin; tooth type convex-

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110 convex; tooth simple, spacing regular, apical angle obtuse or acute; sinus rounded or angular when apical angle of tooth acute; tooth extent on complete margin; three veins entering a tooth, with medial and basal side vein almost the same thickness or with basal vein slightly thinner, basal and apical veins running parallel to tooth margin and joining medial vein at variable vertical distance on medial vein, these veins often accompanied by higher order veins. Primary venation actinodromous; primary veins stout to massive, three primary veins diverging from one single point; primary vein usually thickened at diverging point; primary vein course sinus; medial primacy vein giving ride to 2 to 3 pairs oppositely or sub-oppositely arranged veins with almost the same thickness as primary veins. Primary veins forking numerous times, joining adjacent branches to form meshes irregular in shape and size with long axes oriented perpendicular to the tangent of leaf margin, these veins degrading to veins of tertiary order near margin with one entering a tooth. Tertiary to quinternary veins between lower order veins orthogonal reticulate, forming quadrangular or pentagonal meshes of irregular shape and size. Description. Leaf orbicular, 6 to 11 cm in diameter. Base peltate eccentric (petiole attached near the edge but inside the boundaries of the leaf margin, LAWG, 1999). A spherical floating structure possibly attached. Margin crenate; dentate axes approximately perpendicular to the tangent of margin; crenation type convex-convex; tooth simple, spacing regular, apical angle obtuse or acute; sinus rounded or angular when apical angle of tooth acute; depth of si nus 1 to 2 mm (measured from apex of tooth to bottom of sinus); crenations extent on complete margin; three veins entering a tooth, with medial and basal side veins almost the same thickness or with basal veins slightly thinner, basal and apical veins running parallel to crenation margin and joining medial

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111 vein at variable vertical distance on medial vein, these veins often accompanied by higher order veins. Primary venation actinodromous; primary veins stout to massive, three primary veins diverging from one single point; primary vein usually thickened at diverging point; primary vein course sinus; medi al primary vein giving rise to 2 to 3 pairs oppositely or sub-oppositely arranged veins with almost the same thickness as primary veins. Primary veins forking numerous times, joining adjacent branches to form meshes irregular in shape and size but with long axes oriented perpendicular to the tangent of leaf margin, these veins degrading to veins of tertiary order near margin with one entering a tooth. Tertiary to quinternary veins between lower order veins orthogonal reticulate, forming quadrangular or pentagonal meshes of irregular shape and size. Number of specimens examined. >30. Holotype. UF15706-3666, 3666’. Types. UF15706-14822; 24108, 24108’; 24116. Derivation of Epithet. Latin, “crassus” means “thick, stout” and “nervus” means “nerve,” referring to the stout veins of this species. Discussion. Nelumbites crassinervum is distinguished from Nelumbites fluitus by (1) peltate eccentric base; (2) larger leaf; (3) larger crenations, serrate instead of dentate; (4) fewer (three instead of nine) but thicker primary veins and irregular in course; and (5) primary and secondary veins intergrading with each other so there is no distinctive demarcation between them. Nelumbites crassinervum differs from Nelumbites farleyi by its (1) peltate eccentric leaf base; (2) crenate margin; and (3) stronger primary vein. It is possible that there is a floating structure att ached on leaf petiole (Figure 47, 1). On some specimens (Figure 46, 2; Figure 47, 1), there are carbon materials preserved at the point

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112 where the primary veins are originated. This could be resulted from the thickness of the primary veins or could be resulted from the floating structures attached on the petioles. More and better-preserved specimens need to be examined to verify this. Nelumbites crassinervum is similar to Menispermites virginiensis Fontaine (Fontaine, 1889), but they differ in that Menispermites virginiensis has more primary veins and these veins are more straight in course, and the meshes formed by higher order veins are regularly oriented. Nelumbites farleyi Hongshan Wang sp. nov. (Figure 46, 6-7) Specific diagnosis. Leaf orbicular or slightly oblate, funnel-form. Base peltate central (petiole attached within the boundaries of the leaf margin and near the center of the leaf, LAWG, 1999). Margin entire. Numerous dots (resulted from air lacunae) covering the entire leaf. Primary venation actinodromous; primary vein stout, radiating outward from the center of the leaf; one medial primary vein usually thicker and extending longer distance toward margin than other primary veins; primary vein thickness gradually decreasing toward the opposite direction to medial primary vein; primary veins repeatedly forking and joining adjacent branches to form meshes both irregular in shape and size, intergrading with higher order (secondary or tertiary) vein at ¼ to 1/3 radius near margin. Secondary to quaternary veins intergrading with each other, orthogonal reticulate. Marginal veins possibly quinternary in order and terminating on the margin (perpendicular to the tangent of margin). Description. Leaf orbicular (6 cm in diameter) or slightly oblate (12.2 cm by 10.1 cm), funnel-form. Petiole 4 mm wide. Base peltate central, petiole attached within

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113 the boundaries of the leaf margin and near th e center of the leaf (LAWG, 1999). Margin entire. Numerous dots covering entire leaf. Primary venation actinodromous; primary vein stout, 11 per leaf, radiating outward from the center of the leaf; one medial primary vein usually thicker and extending longer distance toward margin than other primary veins; primary vein thickness gradually decreasing toward the opposite direction to medial primary vein; primary veins repeatedly forking and joining adjacent branch to form meshes both irregular in shape and size, intergrading with higher order (secondary or tertiary) vein at 1/4 to 1/3 radius near margin. Secondary to quaternary veins intergrading with each other, orthogonal reticulate. Marginal veins possibly quinternary in order and terminating on the margin (perpendicular to the tangent of margin). Number of specimens examined. 5. Holotype. UF15706-24103. Paratype. UF15706-14806. Derivation of epithet. In honor of Martin B. Farley and in recognition of his contributions to the collection of Dakota Formation specimens and research on Dakota Formation geology. Discussion. Nelumbites farleyi is most similar to Nelumbites extenuinervis Upchurch et al. (Upchurch et al., 1994) in th at both species have orbicular funnel leaf shape, entire margin, peltate leaf base, actinodromous primary venation with straight course, but it differs from it in having more primary veins (about 11 instead of 5 to 6), distally and proximally arrangement of primary veins, and meshes both irregular in shape and size (Table 5). Nelumbites farleyi differs from Nelumbites fluitus in having (1) larger leaf; (2) entire margin; (3) peltate central base; (4) more primary veins and radially

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114 oriented; and (5) primary to quaternary veins intergrading with each other and the meshes they form not obviously radially oriented (Table 5). Nelumbites farleyi is distinguished from Nelumbites crassinervum by (1) entire margin; (2) more primary veins; (3) peltate central base; and (4) higher order venation pattern (Table 5). Nelumbites farleyi is similar to Menispermites virginiensis Fontaine (Fontaine, 1889) except that Menispermites virginiensis has an undulate or obscurely crenulate margin, and possibly a deeply auriculate leaf base. The primary venation pattern and leaf shape are similar to Menispermites cyclophyllus Lesquereux (Lesquereux, 1883) and Menispermites grandis Lesquereux (Lesquereux, 1883), but both of these two species have percurrent tertiary veins and a peltate eccentric leaf base. Nelumbites farleyi differs from Menispermites dentatus Heer (Heer, 1882) in that the latter has more primaries, crenulate margin, and percurrent veins between adjacent primary veins (Table 5). SAPINDALES Citrophyllum Berry 1911 Emended diagnosis . Leaf simple, lamina unlobed, petiole alate, constricted at the base of the lamina, margin entire, structurally reinforced. Primary venation pinnate. Secondary venation eucamptodromous, festooned brochidodromous; secondary venation often faintly visible or absent on impressions; secondary veins originating from primary vein at acute or moderate acute angles; intercostal regions exmedially elongate, apically curved. Tertiary and higher order venation more or less immersed in the laminar tissue, reticulate. Citrophyllum alteruans (Heer) Hongshan Wang comb. nov.

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115 (Figure 48, 1-7) “Magnolia” alteruans Heer, 1868, Heer, p.73, pl. 55, Figure 1. Specific diagnosis. Leaf simple, whole lamina and base symmetrical. Apex obtuse. Margin entire. Petiole aliform, base inflated; demarcation between lamina wing and leaf lamina distinct. Primary venation pi nnate; primary vein stout, course straight. Secondary venation festooned brochidodromous; secondary veins thin relative to primary vein, subopposite to alternate; angle of divergence moderate acute; secondary veins uniformly curved, joining exmedial branches of superadjacent secondary vein at right or obtuse angles to form two series of loops. Intersecondary veins common, simple. Tertiary veins random reticulate, but tending to be percurrent near leaf margin. Quaternary and quinternary veins random reticulate. Description. Leaf simple, whole lamina and base symmetrical. Form ovate to narrow elliptic, L/W 1.3 to 2.6, lamina 3 to 6 cm wide by 8 cm long. Apex obtuse. Base normal obtuse or cuneate. Margin entire. Petiole aliform, base inflated; petiole 0.5 to 1.8 mm wide by 2.5 cm to 4 cm long; lamina wing 0.2 mm to 1.8 mm wide on each side; demarcation between lamina wing and leaf lamina distinct. Primary venation pinnate; primary vein stout, 0.5 mm to 1 mm wide, cour se straight. Secondary venation festooned brochidodromous; secondary veins thin relative to primary vein, ±9 pairs per leaf lamina, subopposite to alternate; angle of divergence moderate acute (±50º), with lowest pair more obtuse than pairs above; secondary vein uniformly curved, joining exmedial branches of superadjacent secondary vein at right or obtuse angles to form two series of loops. Intersecondary veins common, 1 to 2 between adjacent secondary veins, simple, extending a distance of 1/3 to ½ of half leaf lamina. Tertiary veins random reticulate, but

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116 tending to be percurrent near leaf margin. Quaternary and quinternary veins random reticulate. Number of specimens examined. 6. Holotype. Citrophyllum alteruans Heer, 1868, p.73, pl. 55, Figure 1. Paratypes. UF15706-24332; 24495; 24584; 24645; 24646. Discussion. Citrophyllum aligera differs from Citrophyllum doylei Upchurch and Dilcher (Upchurch and Dilcher, 1990) and “Ficus” aligera Lesquereux (Lesquereux, 1892) in having longer petiole and festooned brochidodromous venation. Some specimens from the Hoisington III locality occasionally don’t have alate petioles. These specimens may represent the further reduction of lamina tissue on the petiole. As discussed by Upchurch and Dilcher (1990), the modern affinities of the genus Citrophyllum is with Sapindales of Eurosids II instead of Rutaceae because it doesn’t possess features that characterize Rutaceae (Upchurch and Dilcher, 1990). Anisodromum Upchurch and Dilcher 1990 Anisodromum wolfei Upchurch and Dilcher 1990 (Figure 42, 2-3; Figure 42, 5-6) Emended specific diagnosis . Leaf compound. Leaflet narrow ovate or elliptic. Base obtuse. Margin entire. Primary vena tion pinnate; primary vein stout, multistranded, course straight. Secondary venation predominately eucamptodromous; secondary veins moderate relative to primary veins, multistranded, opposite or slightly subopposite, decurrent; basal secondary veins joining superadjacent secondary veins or their exmedial branches to form loops very close to margin; other secondary veins uniformly curved and diminishing near margin; adjacent secondary veins connected by percurrent tertiary

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117 veins. Tertiary veins percurrent, moderate relative to secondary veins; course predominately straight, oriented at almost right angle with primary vein; arrangement close. Quaternary vein orthogonal reticulate. Description. Whole lamina and base symmetrical. Form narrow ovate or elliptic, L/W 2 to 2.6, lamina 3 to 4.7 cm wide by 8 to 9 cm long. Apex missing. Base obtuse. Margin entire. Observed petiole with a 0.2 to 0.3 mm wide decurrent lamina tissue; petiole 0.5 mm wide by 2 mm long. Primary venation pinnate; primary vein stout, multistranded, course straight. Secondary venation predominately eucamptodromous; secondary veins moderate relative to primary vein, multistranded, ±9 pairs per lamina, opposite or slightly subopposite, decurrent; angle of divergence moderate acute (45º to 65º), with basal pairs at slightly more obtuse angles; basal secondary veins joining superadjacent secondary veins or their exmedial branches to form loops very close to margin; other secondary veins uniformly curved and diminishing near margin; adjacent secondary veins connected by percurrent tertiary veins. Tertiary veins percurrent, moderate relative to secondary veins; angle of origin AO (acute on exmedial side of secondary vein and obtuse on admedial side of secondary veins) or RO (right on primary vein and obtuse on admedial side of seconda ry vein); course predominately straight, oriented almost at right angle with primary vein; arrangement close (interval between veins less than 0.5 cm). Quaternary vein orthogonal reticulate. Veins of higher order not observed. Number of specimens examined. 3. Paratypes. UF15706-24566, 24566’; 14818. Other specimens examined. UF15706-24782.

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118 Discussion. See Upchurch and Dilcher (1990) for comparison of Anisodromum wolfei with other fossil and modern species. Anisodromum upchurchii Hongshan Wang sp. nov. (Figure 43, 1-2; Figure 43, 5) Specific diagnosis. Lamina base acute, decurrent. Margin entire. Primary venation pinnate; primary vein stout, multistranded, straight. Secondary venation brochidodromous, secondary veins moderate relative to primary vein, opposite, subopposite or alternate; angle of divergence wide acute, uniformly curved apically; secondary vein spacing distant. Intersecondary veins common, usually opposite to a secondary vein on the other side of lamina. Tertiary veins moderate relative to secondary veins, percurrent, course straight, oriented almost at right angles with primary vein. Description. Only fragments of leaves observed. Apex missing. Base acute, decurrent. Margin entire. Primary venation pinnate; primary vein stout, multistranded, straight. Secondary venation brochidodromous, secondary veins moderate relative to primary vein, ±6 pairs per lamina, opposite, subopposite or alternate; angle of divergence wide acute, with lowest pair more acute than pairs above, uniformly curved apically; secondary vein spacing distant (distance between veins 1 to 1.5 cm. Intersecondary veins common, 1 to 2 per intercostal region; extending less than ½ distance of half lamina, usually opposite to a secondary vein on the other side of lamina. Tertiary veins moderate relative to secondary veins, percurrent, course straight; angle of origin AO (acute on exmedial side and obtuse on admedial side of secondary veins or intersecondary vein) or RO (right on primary vein and obtuse on admedial side of secondary or intersecondary

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119 veins), primary vein-tertiary vein angle almost right (90º); tertiary vein interval close (interval between veins less than 0.5 cm). Veins of higher order not observed. Number of specimens examined. 4. Holotype. UF15706-24576. Paratypes. UF15706-24636; 24586; 24634. Derivation of epithet. In honor of Garland R. Upchurch, JR. and in recognition of his contributions to the Dakota Formation angiosperm paleobotany. Discussion. Anisodromum upchurchii differs from Anisodromum wolfei in that it has large angle of divergence of secondary veins, large spacing distance, fewer secondary veins, and intersecondary veins arranged opposite to secondary vein on the opposite side of leaf lamina. MAGNOLIALES Liriophyllum Lesquereux 1878 Liriophyllum kansense Dilcher and Crane 1984 Number of specimens from Hoisington III . 30. Discussion. See Dilcher and Crane (1984a). Clade UNKNOWN Dicotylophyllum leptovena Hongshan Wang sp. nov. (Figure 48, 8; Figure 34, 2) Specific diagnosis. See Systematics: Courtland I locality . Description. Leaf base asymmetrical. Apex missing. Base acute, decurrent. Margin entire. Petiole short, stout, 1 cm long by 1.5 mm wide. Primary venation pinnate; primary vein massive, multistranded, course straight, observed primary vein

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120 about 1.2 mm wide. Secondary venation brochidodromous; secondary veins thin relative to primary vein, 6 pairs observed in a 6 cm long leaf lamina; secondary veins originating from primary vein at wide acute angle (±70º), joining superadjacent secondary veins at a distance of about 1/5 of half lamina to enclose an intercostal region; secondary veins uniformly curved, but becoming sinus when intersect with intersecondary veins. Intersecondary veins always present, 2 to 3 per intercostal region, simple. Tertiary veins course irregular, intersecting with intersecondary veins or random reticulate, anastomosing to form meshes irregular in shape and size. Quaternary veins irregular in course, exmedially ramified or forming incompletely closed meshes irregular in shape and size. Veinlets simple, curved. Vein pattern in excostal region not observed. Number of specimens examined. 1. Paratype. UF15706-24734. Discussion. The specimen from Hoisington III locality has well-preserved higher order veins than the specimens form the Courtland I locality, Minnesota. Meiophyllum Hongshan Wang gen. nov. Generic diagnosis (emended). Leaf simple, five-lobed; apex of lobes obtuse; margin toothed; sinus rounded; serrations minute, simple; serration type variable from concave to straight on apical side and stra ight to convex on basal side, spacing irregular; typically three veins entering a tooth, medial vein originating form exmedial side of secondary vein, basal vein tertiary in order and running very close to the margin before entering the tooth, vein of apical side not well developed. Primary venation basal actinodromous; medial primary vein straight in course; inner lateral primary veins apically curved; outer primary veins apically curved or recurved. Secondary venation

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121 predominately brochidodromous or semicraspedodromous when margin is toothed; secondary veins thin relative to primary veins. Derivation of generic name. Chinese, “mei” means “beautiful,” in honor of Professor Mei Meitang and in recognition of her contributions to the Chinese paleobotany. Meiophyllum expansolobum (Upchurch and Dilcher) Hongshan Wang comb. nov. (Figure 37, 1-6; Figure 38, 1-8) Meiophyllum expansolobum Upchurch and Dilcher 1990, U.S. Geological Bulletin, pl.4849, Figures 1-4; text Figure 25. Specific diagnosis. Leaf simple, five-lobed; medial lobe narrow obovate, narrow ovate or narrow oblong, symmetrical; inner lateral lobes asymmetrical, shape irregular, curved apically; outer lateral lobes occasionally underdeveloped (leaf tending to be trilobate); apex of lobes obtuse; base of lamina obtusely cuneate or strongly rounded to give a truncate appearance; margin toothed near apex of lobes, strongly reinforced; sinus rounded, bracing accomplished by two secondary veins originated from adjacent primary veins, these two veins join and then fork to run along the margin; serrations minute, simple; serration type ranging from concave to straight on apical side and straight to convex on basal side, spacing irregular; typically three veins entering a tooth, medial vein originating form exmedial side of secondary vein, basal vein tertiary in order and running very close to the margin before entering the tooth, vein of apical side not well developed. Petiole long, thin, base swollen; thickened lamina structure always present at the junction of petiole and lamina base and extending up to 1 cm proximally along the petiole. Primary venation basal actinodromous; primary vein stout to massive, multistranded;

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122 medial primary vein straight in course; inner lateral primary veins apically curved; outer primary veins apically curved or recurved. Secondary venation predominately brochidodromous or semicraspedodromous when margin is toothed near apex; secondary veins thin relative to primary veins; originating from primary veins at wide acute to angle, straight or slightly curved and then abruptly curved very close to the margin to join superadjacent secondary veins to form rectangular or rhomboidal intercostal regions; typically one series of loops present in the excostal region if margin is entire; secondary veins below sinus and between adjacent primary veins forming inverted ‘V’ pattern. Intersecondary veins common, composite, 1 to 3 per intercostal region. Tertiary veins orthogonal reticulate, forming predominately quadrangular meshes, tending to be percurrent and arranged at very oblique angles with primary veins. Quaternary veins orthogonal reticulate. Description. Leaf simple, five-lobed, lamina varies from 3.2 cm long by 6 cm wide to 15 cm long by 15 cm wide; sinus deep, extending ¾ to 4/5 of distance from apex to lamina base; medial lobe narrow obovate, narrow ovate or narrow oblong, symmetrical; lateral lobes asymmetrical, shape irregular, curved apically; outer lobes occasionally underdeveloped (leaf tending to be trilobate); apex of lobes obtuse; base of lamina obtusely cuneate or strongly rounded to give a truncate appearance; margin toothed near apex of lobes, strongly re inforced; sinus rounded, bracing accomplished by two secondary veins originated from adjacent primary veins, these two veins join and then fork to run along the margin; serrations minute, simple; serration type ranging from concave to straight on apical side and stra ight to convex on basal side, spacing irregular; typically three veins entering a tooth, medial vein originating form exmedial side of

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123 secondary vein, basal vein tertiary in order and running very close to the margin before entering the tooth, vein of apical side not well developed. Petiole long, thin, 8 cm long by 1 mm wide; petiole base swollen; thickened lamina structure always present at the junction of petiole and lamina base and extending up to 1cm proximally along the petiole. Primary venation basal actinodromous; primary veins stout to massive, multistranded; medial primary vein straight in course; inner lateral primary veins apically curved; outer primary veins apically curved or recurved. Secondary venation predominately brochidodromous or occasionally semicraspedodromous near apex; secondary veins thin relative to primary veins; originating from prim ary veins at wide acute angles, straight or slightly curved and then abruptly curved very close to the margin to join superadjacent secondary veins to form rectangular or rhomboidal intercostal regions; typically one series of loops present in the excostal region if margin is entire; secondary veins below sinus and between adjacent primary veins forming inverted ‘V’ pattern. Intersecondary veins common, composite, 1 to 3 per intercostal region. Tertiary veins orthogonal reticulate, forming predominately quadrangular meshes, tending to be percurrent and arranged at very oblique angles (<20º) with primary veins. Quaternary veins orthogonal reticulate. Veins of higher order not observed. Number of specimens examined. 52. Holotype. UF15720304, 8304’ (Upchurch and Dilcher, 1990, p.48, pl.31, Figures 1-4). Paratypes. UF15705-14825, 14825’; 14826; 14827; 14828, 14828’; 24461; 24788, 24788’; 30158; 31448, 31448’.

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124 Discussion. This species was first described by Upchurch and Dilcher (1990). Their observation was based on one specimen from the Rose Creek I locality, Nebraska. Observations on the Hoisington III locality specimens yield more information on this species, especially the variations of leaf morphology. For example, secondary venation of Meiophyllum expansolobum can vary from predominately brochidodromous to semicraspedodromous. High order venation (tertiary and quaternary veins) is well preserved on the specimens from Hoisington III locality, Kansas. Meiophyllum kowalskiae Hongshan Wang sp. nov. (Figure 34, 3; Figure 37, 7-8) Specific diagnosis. Leaf simple, five-lobed; medial lobe narrow ovate, symmetrical; inner lateral lobes asymmetrical, curved apically; apex of lobes obtuse or slightly acute; base of lamina obtusely cuneate or truncate; margin toothed; sinus rounded; serrations minute, simple; serration type ranging from concave to straight on apical side and straight to convex on basal side, spacing irregular; typically three veins entering a tooth, medial vein originating form exmedial side of secondary vein, basal vein tertiary in order and running very close to the margin before entering the tooth, vein of apical side not well developed. Primary ve nation basal actinodromous; primary vein thin, multistranded; medial primary vein straight in course; inner lateral primary veins apically curved; outer primary veins apically curved or recurved. Secondary venation semicraspedodromous; secondary veins thick relative to primary veins; originating from primary veins at moderate acute angle, slightly curved in course; connected with superadjacent secondary veins by tertiary order cross veins. Tertiary veins orthogonal reticulate.

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125 Description. Leaf simple, five-lobed, leaf 4 cm long by 8 cm wide (estimated maximum width); sinus deep, extending ¾ to 4/5 of distance from apex to lamina base; medial lobe narrow ovate, symmetrical; lateral lobes asymmetrical, curved apically; apex of lobes obtuse or slightly acute; base of lamina obtusely cuneate or truncate; margin toothed; sinus rounded; serrations minute, si mple; serration type ranging from concave to straight on apical side and straight to c onvex on basal side, spacing irregular; typically three veins entering a tooth, medial vein originating form exmedial side of secondary vein, basal vein tertiary in order and running very close to the margin before entering the tooth, vein of apical side not well devel oped. Petiole not observed. Primary venation basal actinodromous; primary veins thin, multistranded; medial primary vein straight in course; inner lateral primary veins apically curved; outer primary veins apically curved. Secondary venation semicraspedodromous; secondary veins thick relative to primary veins; originating from primary veins at moderate acute angle, slightly curved. Tertiary veins orthogonal reticulate. Veins of higher order not observed. Number of species examined . 2. Holotype. UF15705-14824, 14824’. Paratypes. UF15705-24460; Derivation of epithet. In honor of Elizabeth A. Kowalski and in recognition of her contributions to paleobotany. Discussion. Meiophyllum kowalskiae is distinguished from Meiophyllum expansolobum in having smaller leaves, relatively thin secondary veins, semicraspedodromous secondary venation, and toothed margin. Jaramillophyllum Hongshan Wang gen. nov.

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126 Generic diagnosis. Leaf simple, spatulate; leaf base with a strong decurrent lamina tissue. Margin structurally reinforced. Primary venation pinnate; primary vein thick. Secondary venation craspedodromous. Derivation of generic name. In honor of Carlos A. Jaramillo and in recognition of his contributions to paleobotany. Discussion. The new genus is set up to represent those leaves with a unique spatulate leaf shape, base with a strong decurrent lamina tissue, and craspedodromous secondary venation. Jaramillophyllum celatus (Lesquereux) Hongshan Wang comb. nov. (Figure 32, 1) Phyllites celatus Lesquereux, 1892, U.S. Geological Survey Monograph 17, pp.215-216, pl.61, Figure 1 Specific diagnosis. Same as for genus. Description. Leaf 12 cm long (estimated length) by 9 cm wide. Base with a strong decurrent lamina tissue, at least 3 cm long by 1.2 cm wide. Margin structurally reinforced. Primary venation pinnate; primary vein 2 mm thick at middle portion of leaf lamina, curved. Secondary venation craspedodromous; secondary veins at least 5 pairs, subopposite, diverging from primary vein at moderate acute angle (±60º), with the basal pair at more acute angles than pairs above. Number of specimens examined. 1. Holotype. Jaramillophyllum celatus Lesquereux, 1892, U.S. Geological Survey Monograph 17, pp.215-216, pl.61, Figure 1. Paratypes. UF15706-24491.

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127 Discussion. This species differs from all othe r Dakota Formation angiosperm leaf megafossils by its unique shape, strong primary vein, and its strong decurrent lamina tissue on the petiole, which gives an appearance of peltate leaf base. Phyllites is a genus established by Brongniart (1822) for Miocene dicot leaves from Oeningen, Switzerland. The genus is based on Phyllites populina (Brongniart, 1822). The genus includes a miscellaneous assemblage of leaves of doubtful affinity (Andrews, 1970). I move Phyllites celatus Lesquereux (Lesquereux, 1892) out and assign it to the new genus Jaramillophyllum . Wingia Hongshan Wang gen. nov. Generic diagnosis. Lamina margin entire. Primary venation pinnate; primary vein stout, multistranded, course straight. Secondary venation festooned brochidodromous; secondary veins moderate relative to primary veins, subopposite to alternate, decurrent, spacing irregular, with one side more closely spaced than the other side; secondary vein curved apically, joining tertiary veins from superadjacent secondary veins to form two series of loops. Tertiary veins moderate relative to secondary veins, predominately percurrent, orthogonal reticulate near primary vein; course irregular, straight or sinuous; primary-tertiary vein angle oblique. Type species. Wingia anisos . Derivation of generic name. In honor of Scott Wing and in recognition of his contributions to paleobotany. Discussion. The new genus Wingia is set up for those angiosperm leaves from the Dakota Formation with entire margin, festooned brochidodromous secondary venation, secondary vein spacing with one side more closely spaced than those on the

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128 other side; secondary veins curved apically, joining tertiary veins from superadjacent secondary veins to form two series of loops, and predominately percurrent tertiary veins. Wingia anisos Hongshan Wang sp. nov. (Figure 43, 3-4) Specific diagnosis. Same as for genus. Description. Whole lamina and base symmetrical, lamina elliptic, L/W 1.5, lamina 2.9 cm to 3.1 cm wide by 4.5 cm to 5.5 cm long. Apex obtuse. Base acute normal. Margin entire. Petiole not observed. Primary venation pinnate; primary vein stout, multistranded, course straight. S econdary venation festooned brochidodromous; secondary veins moderate relative to primary vein, ±7 pairs per lamina, subopposite to alternate, decurrent, spacing irregular, with one side more close than the other side; angle of divergence narrow acute to moderate acute (45 to 65º), with one side apparently more acute than those of the other side; secondary vein curved apically, joining tertiary veins from superadjacent secondary veins to form two series of loops. Tertiary veins moderate relative to secondary veins, predominately percurrent, orthogonal reticulate near primary vein; angle of origin (AO); course irregular, straight or sinuous; primary-tertiary vein angle oblique. Veins of higher order not observed. Number of specimens examined. 2. Holotype. UF15706-24633. Paratype. UF15706-24635. Derivation of epithet. Greek, “anisos” means “unequal,” referring the uneven spacing of secondary veins.

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129 Discussion. Characters such as entire margin, multistranded primary vein, and festooned brochidodromous secondary venation indi cate the affinity of this species with Magnoliales, but the uneven secondary vein spacing may indicate the leaf is compound, which excludes the assignment to the Magnoliales. Springfield and Pleasant Dale Localities, Nebraska MAGNOLIIDS MAGNLIALES Jarzenia Hongshan Wang gen. nov. Jarzenia kanbrasota Hongshan Wang sp. nov. (Figure 63, 5-8; Figure 50, 1-6; Figure 50, 9-10) Description. Leaf oblanceolate or narrow obovate, L/W 2 to 3, 5.5 cm to 11 cm long by 3.5 cm to 4 cm wide; apex obtuse; base acute, normal; margin entire; petiole not observed. Primary venation pinnate; primary vein stout, straight or slightly curved, multistranded. Secondary venation brochidodromous; secondary veins 6 to 10 pairs, subopposite, moderate in thickness relative to primary vein, originating from primary vein at moderate acute angles (45 to 65 ), with lowest one or two pairs more acute than pairs above; secondaries straight at 2/3 distance from primary vein to margin and then curved gradually to joining exmedial branches of superadjacent secondaries at obtuse angles to form loops; intercostal and excostal region not well defined; two basal thin secondaries originating at extreme base of lamina and runs very closely along the margin (less than 0.5 mm to the margin). Intersecondaries present, no more than one per intercostal region, extending half distance to the margin before intergrading or branching to form tertiaries.

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130 Number of specimens examined. 13. Paratypes. UF18038-31738; 31745; 31749; 31751. Discussion. This species is very common from the Courtland I locality, Minnesota. LAURALES cf. LAURACEAE Rogersia Fontaine 1889 Rogersia parlatorii Fontaine 1889 (Figure 65, 5-9) Description. Leaflet (?) symmetrical, base symmetrical to slightly asymmetrical; form oblong, lorate to linear, L/W ratio 6 to 10 or more; apex acuminate with a sharp tip; base acute, cuneate, demarcation between lamina and petiole indistinct. Margin entire. Petiole normal, up to 2 mm wide by 1 cm long. Primary venation pinnate; primary vein stout, multistranded, course straight (Figure 65, 5; Figure 65, 7-8), or markedly curved (Figure 65, 9). Secondary venation brochidodromous; secondary veins moderate in thickness, irregularly spaced; angle of divergence narrow acute (less than 45 ), with lowest 3 to 5 pairs more acute than those above and much thinner; course of secondary veins sinuous, joining superadjacent secondary veins or exmedial branches of superadjacent secondary veins at obtuse angles to form very irregular loops; intercostal area very elongate and admedially oriented; order of arches (secondary to quaternary) in excostal region indistinct and irregular in shape, but all elongate and tending to be parallel oriented to the margin; intersecondary veins common, difficult to distinguish from secondary veins by thickness, one (occasionally two) per intercostal area. Tertiary

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131 veins thick, sometimes integrading with intersecondary or quaternary veins, tending to be percurrent; angle of origin irregular, predom inately acute-obtuse (AO), course straight convex, relationship to primary vein (primary vein-tertiary vein angle) irregular; arrangement predominately alternate. Number of specimens from Pleasant Dale locality . 50. Paratypes. UF18038-31759; 31760; 31763; 31833; 31836. Discussion. See Braun locality systematics. Rogersia cf. R. parlatorii Fontaine 1889 (Figure 65, 10-11) Description. Base and apex missing; form possibly oblong; observed lamina. Margin entire. Primary venation pinnate; primary vein stout, slightly curved. Secondary venation brochidodromous; secondary vein moderate relative to primary vein, opposite to subopposite, decurrent on primary vein, spacing irregular; angle of divergence narrow acute ( 20 ), course straight, curved abruptly near margin to join super adjacent secondary vein or intersecondary vein form elongate intercostal region, whose long axis also at sharp angle ( 20 ) with primary vein; shape of intercostal region more or less irregular; in the excostal region, one more series of loops of tertiary order may enclose the intercostal region. Intersecondary veins common, simple, one per intercostal region, extending to a distance almost the same as that of secondary veins. Veins of higher order not observed. Number of specimens examined. 13. Paratype. UF18038-31739.

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132 Discussion. The entire margined leaf, secondary venation pattern, and the presence of intersecondary veins of these specimens are similar to Rogersia parlatorii , these specimens were assigned to Rogersia cf. R. parlatorii due to the lack of higher order venation patterns (Table 3). Rogersia kansense Hongshan Wang sp. nov. (Figure 63, 4; Figure 64, 3; Figure 65, 1-4) Description. Leaf lamina form linear oblong, L/W 10:1, 6.5 cm to 14 cm long by 0.5 cm to 1.3 cm wide. Apex possibly attenuate. Base acute, decurrent. Petiole normal, about 1 cm long by 1 mm wide. Margin entire. Primary venation pinnate; primary vein stout, straight or slightly curved. Secondary venation brochidodromous; secondary veins thin relative to primary vein, 15 pairs per leaf lamina; opposite to subopposite, decurrent on primary vein, spacing irregular; angle of divergence narrow acute (20 to 30 ); course somewhat irregular, straight or curved before joining super adjacent secondary or recurved intersecondary veins to form loops at a distance of 1/5 distance from primary vein to margin, enclosing an elongate intercostal region with long axis also at an narrow acute angle (20 to 30 ) to primary vein; one series of loops of higher order probably occupying the excostal region. Intersecondary veins present, recurved or retroflexed to join lower (proximal) secondary veins. Tertiary veins difficult to see clearly but appear to from right angle connections between secondary veins. Number of specimens examined. 43. Paratypes. UF18038-31762; 31766, 31766Â’; 31768; 31772; 31780. Discussion. See BraunÂ’s Ranch Locality systematics. Pabiania Upchurch and Dilcher 1990

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133 Pabiania variloba Upchurch and Dilcher 1990 (Figure 71, 1; Figure 71, 3; Figure 71, 6) Description. Leaf unlobed. Leaf shape varying from orbiculate (Figure 71, 1) to suborbiculate (Figure 71, 6), L/W 1 to 1.5. Base acute (Figure 71, 6) to obtuse (Figure 71, 1) and tending to cuneate, with the basalmost portion of the lamina decurrent on the petiole. Petiole thin (Figure 71, 6), up to 3 cm long; margin entire; apex rounded. Primary venation suprabasal actinodromous. Secondary venation brochidodromous; secondary veins thin, 3 to 6 pairs, with one pair of basilaminar secondary veins present; secondary veins straight (Figure 71, 6) to ap ically curved (Figure 71, 1; Figure 71, 3). Veins of higher order not observed. Number of specimens examined. 4. Paratypes. UF18047-31589; 31605; 31606. Other specimens examined . 18047-31591. Discussion. This species is abundant in the Rose Creek I locality of Nebraska. Only poorly preserved specimens from Springfield locality are observed. Based on their leaf shape, suprabasal actinodromous venation, these specimens are assigned to Pabiania variloba . It is worth noting that all four specimens from the Springfield locality are unlobed. If enough specimens are available for examination, result may show that the unlobed specimens possibly represent a different species of the Pabiania . Manchesterii Hongshan Wang gen. nov. Manchesterii macrophylla (Lesquereux) Hongshan Wang comb. nov. (Figure 61, 1-6; Figure 52, 1-2, 4-6) “Ficus” macrophylla Lesquereux, 1892, p.76, pl.11, Figure 1.

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134 Specific diagnosis. Leaf narrow oblong to lorate. Base acute, decurrent. Margin entire, slightly undulate, strongly structurally reinforced. Petiole normal, short, stout. Primary venation pinnate; primary vein stout to massive, course straight. Secondary venation brochidodromous; secondary veins thin or moderate relative to primary vein, sub-opposite, somewhat regularly spaced, slightly decurrent on the primary vein, originating at wide acute angles (65º to 80º), uniformly curved in course; secondary vein joining exmedial (lower) branches of super-adjacent secondary vein at obtuse angles to form three series of exmedial loops; exmedially brochidodromous arches rectilinear. Intersecondary veins common, one per intercostal region, with one tertiary vein arising from primary vein between and parallel to secondary and intersecondary veins, extending ¼ to 1/3 distance of from primary vein to the margin. Intercostal tertiary vein orthogonal reticulate, originating at right angles from primary, secondary, and intersecondary veins; excostal tertiary veins reticulate, anastomosing with secondary veins, approximately at right angles to primary vein. Intercostal quaternary veined irregularly reticulate; excostal quaternary venation randomly reticulate; quint ernary venation dominantly rectangular, or occasionally ultimate veins originating from quinternary veins and branching once appearing to form open venation pattern. Description. Leaf narrow oblong to lorate; L/W ratio at least 5:1, lamina 25 cm long (estimated leaf length) by 5 cm wide. Apex possibly attenuate. Base acute, decurrent. Margin entire, strongly structurally reinforced, sometime with a bumpy edge resulting from 0.25 mm to 0.8 mm extensions of apparent glandular thickenings. Petiole normal, short, stout, 1.5 cm long by 3 mm wide (Figure 61, 6). Primary venation pinnate (with a single primary vein serving as the origin for higher order venation); primary vein

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135 stout to massive (ratio of vein width to leaf width 2% to 4% or more, determined midway between the leaf apex and base), course straight. Secondary venation brochidodromous (secondary veins joined together in a series of prominent arches); secondary veins thin or moderate relative to primary vein, sub-opposite, somewhat regularly spaced, slightly decurrent on the primary vein, originating at wide acute angles (65º to 80º), uniformly curved in course; secondary vein joining exmedial (lower) branches of super-adjacent secondary vein at obtuse angles to form three series of loops, diminishing along the darkened thickening at the margin; exmedially brochidodromous arches rectilinear. Intersecondary veins common, one per intercostal region, with one tertiary vein arising from primary vein between and parallel to secondary and intersecondary veins, extending ¼ to 1/3 distance of half lamina. Intercostal tertiary vein orthogonal reticulate, originating at right angles from primary, s econdary, and intersecondary veins; excostal tertiary veins reticulate, anastomosing with secondary veins, approximately at right angles to primary vein. Intercostal quaternary veined irregularly reticulate; excostal quaternary venation randomly reticulate; quint ernary venation dominantly rectangular, or occasionally ultimate veins originating from quinternary veins and branching once appearing to form open venation pattern. Quaternary and quinternary feed directly into a broad marginal area, which appears reinforced with glands densely arranged at the leaf margin (15 to 16 glands per cm) forming a bumpy edge. Number of specimens examined. 16. Holotype. Manchesterii macrophylla Lesquereux 1892, p.76, pl.11, Figure 1. Paratype. UF18267-16600, 16600' (part and counterpart); UF18844-32485; UF18038-31702, 31702’; 31703; 31705, 31705’; 31719; 32198.

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136 Other specimens examined. UF18038-31704; 31706, 31706Â’; 31707; 31708; 31709; 31710; 31718; 31720; 31721, 31721Â’; 31758, 31758Â’. Discussion. See Courtland I locality Systematics. SAXIFRAGALES Dumort. cf. CERCIDIPHYLLACEAE Trochodendroides Berry 1922 Trochodendroides rhomboideus (Lesquereux) Berry 1922 (Figure 64, 7; Figure 51, 1-7; Figure 51, 10) Description. Basal portion of leaf observed (Figure 64, 7). Petioles thin. Base obtuse, decurrent. Primary venation perfectly basal acrodromous; medial primary vein moderate, multi-stranded; lateral primary veins originating from petiole; medial primary vein straight, almost the same thickness as that of lateral primary veins; one exmedial branch arising from each lateral primary vein very close to the base; exmedial branches from these veins originating at narrow acute angles, abruptly curved to join superadjacent branches at right or obtuse angles to form loops, which are enclosed by higher order arches. Tertiary veins random reticulate, course irregular. Number of specimens examined. 1. Paratype. UF18038-31733. Discussion. Only one fragmentary specimen from Pleasant Dale locality has been found. This specimen is assigned to Trochodendroides rhomboideus based upon the following characters: obtuse leaf base, thin petiole, and perfectly basal acrodromous primary venation. This species is abundant in the Courtland I locality, Minnesota (Figure 51, 1-7; Figure 51, 10).

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137 Clade UNKNOWN Sungia Hongshan Wang gen. nov. Generic diagnosis. Leaf simple, trilobed; sinuses between lobes deep. Base cuneate. Margin of lobes entire. Petiole normal. Primary venation actinodromous, multistranded; position of primary veins basal, perfect, with lateral primary veins recurved. Secondary venation brochidodromous; secondary veins fine to hair like relative to primary veins; angle of divergence moderate acute above the sinuses and narrow acute below the sinuses; course abruptly curved, joining super adjacent secondary veins at obtuse angle very close to the margin to form a rhomboid intercostal region, with joined secondary veins running along the margin and appearing to form an intramarginal vein. Intersecondary veins common, relatively thick compared with secondary veins. Higher order veins random reticulate. Derivation of generic name. In honor of Ge Sun and in recognition of his contributions to the Chinese paleobotany. Sungia delicatus Hongshan Wang sp. nov. (Figure 62, 1-5) Specific diagnosis. Same as for genus. Description. Leaf simple, deeply trilobed, sinuses, extending about ½ the distance between apex of the medial lobes to base of leaf lamina, angles between medial and lateral primary veins about 40 ; lamina length less than 10 cm (observed from lamina base to apex of the medial lobe); whole lamina symmetrical. Apex of lobes probably acuminate. Base cuneate. Margin of lobes entire. Petiole normal, thin, 3 cm long by 1 mm wide. Primary venation actinodromous (thr ee primary veins diverging radially from

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138 a single point); primary veins stout (2% to 4% ratio of vein width to lamina width at middle portion of lobes), multistranded; position of primary veins basal, perfect (lateral primary veins cover 2/3 lamina), with opposite lateral primary veins recurved. Secondary venation brochidodromous; secondary veins very thin or hair-like relative to primary veins; angle of divergence moderate acute above the sinuses and narrow acute below the sinuses, spacing somewhat irregular, decurrent on primary vein; course abruptly curved, joining super adjacent secondary veins at obtuse angle very close to the margin to form a rhomboid intercostal region, with joined secondary veins running along the margin and appearing to form an intramarginal vein. Intersecondary veins common, relatively thick compared with secondary veins, sometimes difficult to distinguish them by thickness; two or more per intercostal region. Tertiary veins random reticulate. Quaternary veins random reticulate. No specific venation pattern observed between medial and lateral primary veins, secondary veins arising from lateral primary veins generally terminate on secondary veins arising from medial primar y vein. Veins of higher order not observed. Number of specimens examined. 9. Holotype. UF18038-31724, 31724’ (part and counterpart). Other specimens . UF18038-31722; 31723; 31725; 31726; 31727; 31728; 31729; 31737. Derivation of epithet. Latin, “delicatus” means “delicate,” referring to the delicate, thin secondary and higher order veins of this species. Discussion. The new genus is set up for those Dakota Formation specimens with simple trilobed leaf, actinodromous primary venation, brochidodromous secondary venation, very thin or hair-like secondary and higher order veins, secondary veins

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139 forming rhomboid intercostal regions with joined secondary veins running along the margin and appearing to form an intramarginal vein, and common intersecondary veins. This suite of features is not observed in any other Dakota Formation angiosperm leaves. Sungia delicatus is similar to “Sterculia” reticulata Lesquereux (Lesquereux, 1892) but it differs from “Sterculia” reticulata because Sungia delicatus has relatively thin secondary veins and common intersecondary veins which are difficult to distinguish from secondary veins just by their thickness. PROTEALES cf. PLATANACEAE Sapindopsis Fontaine 1889 Sapindopsis retallackii Hongshan Wang sp. nov. (Figure 66, 1-8; Figure 67, 1-5; Figure 63, 1-2) Specific diagnosis. Leaf compound, with three or four leaflets; most commonly three leaflets closely arranged on the rachis on the distal portion, occasionally with one leaflet attached on rachis at a certain dist ance away proximally; rachis thin. Leaflet lorate, always curved abaxially (downward); apex attenuate; base normal acute; petiolule varies from lacking (lateral leaflets) to up to 1.5 cm long (medial leaflet); margin entire, usually revolute. Primary venation pinnate; primary vein stout; course straight (medial leaflet) or recurved (lateral leaflets). Secondary venation brochidodromous; secondary veins thin relative to primary vein; opposite to subopposite, decurrent; angle of divergence acute, joining superadjacent secondary veins to form a loop enclosing an intercostal area, with two series of loops (tertiary and quaternary in order) in excostal region; exmedial branches of secondary veins common, forming tertiary veins.

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140 Intersecondary veins common. Tertiary vein moderate; orthogonal reticulate but tending to be percurrent, retroflexed. Quaternary veins random reticulate, forming incompletely closed meshes. Veinlets simple, linear. Description. Leaf compound, with three (Figure 63, 1; Figure 66, 1, 66, 7-8) or four leaflets (Figure 67, 2); most commonly three leaflets closely arranged on the rachis on the distal portion, occasionally with one leaflet attached on rachis at a certain distance away proximally; leaflets of 2 or 4 closel y arranged on distal portion of rachis also observed; rachis thin, at least 3 cm long by 1 mm wide. Whole leaflet lamina and base asymmetrical, lorate, L/W > 6:1, always curved abaxially (downward); apex attenuate; base normal acute; petiolule varies from lacking (lateral leaflets) to up to 1.5 cm long (medial leaflet); margin entire, usually revolute. Primary venation pinnate; primary vein stout, up to 1 mm wide, multistranded; course stra ight (medial leaflet) or recurved (lateral leaflets). Secondary venation brochidodromous; secondary veins thin relative to primary vein; opposite to subopposite, decurrent; spacing somewhat irregular, 2 to 3 veins per cm on most leaflets; angle of divergence moderate acute (about 65 ), joining superadjacent secondary veins to form a loop enclosing an intercostal area, with two more series of loops (tertiary and quaternary) in excostal region; exmedial branches common, forming tertiary veins (Figure 67, 1, 3; Figure 63, 2). Intersecondary veins common (Figure 67, 1, 3), one per intercostal region, simple; sometimes veins of tertiary order arising from the exmedial side of secondary vein or intersecondary vein to form one more composite intersecondary vein (Figure 67, 5). Tertiary vein moderate; orthogonal reticulate but tending to be percurrent, retroflexed. Quaternary veins random reticulate, forming

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141 incompletely closed meshes (one or more sides of the mesh not bounded by vein). Veinlets simple, linear. Number of specimens examined. 29. Holotype. UF18047-31583 (Figure 67, 1-3). Paratypes. UF18047-31563; 31564; 31566; 31567; 31569; 31571; 31572; 31585. UF18038-31730. Derivation of epithet. In honor of Greg J. Retallack and in recognition of his contributions to the Dakota Formation geology. Other specimens. UF18047-31562; 31565; 31568; 31579; 31573; 31574; 31575; 31576; 31577; 31578; 31579; 31580; 31581; 31582; 31584; 31586, 31586Â’; 31587; 31597; 31598. Discussion. Sapindopsis retallackii is similar to Sapindopsis bagleyae (Figure29, 1-5; Figure28, 1-7; Figure30, 1-7) in having compound leaf with entire margined leaflets and the presence of intersecondary veins, but they differ in that the latter has eucamptodromous or slightly brochidodromous secondary venation, predominately percurrent, thick tertiary veins relative to secondary veins, and orthogonal quaternary veins. Sapindopsis retallackii is similar to Sapindopsis sp. A (Huang and Dilcher, 1994) in having three leaflets but they differ in that Sapindopsis retallackii occasionally has four leaflets, lorate leaflets, and brochidodromous secondary venation. PLATANACEAE Credneria Zenker emend. Schwarzwalder and Dilcher Credneria cf. Credneria cyclophylla (Heer) Hongshan Wang comb. nov. (Figure 64, 4-5)

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142 Description. Middle and basal portion of leaf observed (Figure 64, 4). Leaf shape possibly ovate, L/W 1, observed lamina 6 cm long by 5.6 cm wide; base decurrent. Primary venation pinnate; primary vein thin, straight, multistranded. Secondary venation simple craspedodromous; two prominent basal secondaries depart from primary vein at extreme base of lamina; generally 4 to 5 exmedial branches from secondaries of the lowest pair apically curved. Tertiaries moderate relative to secondary vein, percurrent, course convex; angle of origin right-acute (RA) or right-right (RR), course convex; primary vein-tertiary angle oblique, decreasing upward. Quaternary veins thin, transverse, predominately orthogonal, arrangement predominately opposite; quinternary veins moderate relative to quaternary veins, orthogonal; areoles formed by quinternary veins well developed, randomly arranged, pentagonal in shape, small in size (Figure 64, 5). Number of specimens examined. 1. Type. UF18038-31734. Discussion. One specimen with middle and basal portion of leaf is examined from the Pleasant Dale locality. The venation pattern is very similar to Credneria cyclophylla (Heer) Wang from the Courtland I locality of Minnesota. Because the leaf margin is not observed, it is hard to determine whether it represents a different species. Eurylobum Schwarzwalder and Dilcher 1986 Emended generic diagnosis: Fossil leaf, lamina undivided, with three to five lobes; perfoliate; angle of lamina base moderate; base of lamina protracted or with projections; apex angle broad; incision between lobes moderate; primary venation actinodromous or palinactinodromous; suprabasal primary veins robust, equal in strength

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143 to medial primary vein; majority of secondary veins craspedodromous; secondary veins arising at moderate angles, wide spaces; tertiary veins convex in axils of primary veins, percurrent to reticulate. Discussion. The genus Eurylobum was erected by Schwarzwalder (1986) to accommodate Eurylobum dentatum , a very unique Platanoid leaf from the Dakota Formation. The generic diagnosis was emended to accommodate those specimens with actinodromous primary venation from the Springfield locality, Nebraska. Eurylobum dentatum Lesquereux emend. Schwarzwalder and Dilcher 1986 (Figure 69, 1-2; Figure 69, 4-5; Figure 70, 1-4) Aspidiophyllum dentatum Lesquereux, 1883, Rept. U.S. Geol. Surv. Terr., vol.8 (Cretaceous and Tertiary Flora), p.88 (only description). Aspidiophyllum dentatum Lesquereux, 1892, U.S. Geological Survey Monograph 17, p.212, pl.39, Figure 1. Eurylobum dentatum (Lesquereux) Schwarzwalder and Dilcher, 1986, Schwarzwalder, Ph.D. thesis, p.59. (Briefly mentioned. No figures). Specific diagnosis. Leaf three lobed. Apex of lobes rounded. Base peltate or auricular. Margin lobed or wavy. Primary venation suprabasal actinodromous; primary veins moderate in thickness. Secondary venation craspedodromous; secondary veins typically 4 to 5 pairs; secondary vein spacing irregular and decreasing distally; secondary veins originating from primary vein at moderate acute angles, each extending to the apex of a lobe; sinuses rounded; on lobed margin, veins originating from adjacent secondary veins (tertiary veins) form a series of inverted ‘V’s below sinus and brochidodromous above sinus, these tertiary loops may be enclosed by one or two more series of loops

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144 formed by veins of higher order; if margin is wavy, tertiary veins tending to be percurrent or form inverted ‘V’s but with irregular course and spacing. Quaternary veins in the excostal region and below sinus between secondary veins predominately percurrent, course straight or curved. Quinternary veins orthogonal reticulate, joining others to form imperfect areoles or incompletely enclose meshes, then giving rise to simple, linear or curved veinlets. Below lateral primary veins and peltate petiole base, 2 pairs of veins of tertiary order originating from primary veins, recurved and extending to the wavy leaf margin. Description. Leaf three lobed. Leaf size large. One observed incomplete leaf 13.5 cm long by at least 10 cm wide (Figure 69, 4). Apex of lobes rounded (Figure 69, 1). Base peltate or auricular (Figure 69, 5). Margin lobed or wavy (Figure 69, 2). Primary venation actinodromous; primary vein moderate in thickness; lateral primary veins diverging at a point about 1 cm from the petiole base. Secondary venation craspedodromous (Figure 69, 2); secondary veins moderate in thickness, subopposite or alternate; typically 4 to 5 pairs; secondary vein spacing irregular and decreasing distally; between medial and lateral primary veins, there are two or three pairs of veins of tertiary order originating from the medial primary vein; secondary veins originating from primary vein at moderate acute angles ( 45 ), each extending to the apex of a lobe; sinuses rounded, depth varying from slightly wavy to ½ distance from margin to primary vein; on lobed margin, veins originating from adjacent secondary veins (tertiary veins) form a series of inverted ‘V’s below sinus and brochidodromous above sinus, these tertiary order loops may be enclosed by one, two or more series of loops formed by veins of higher orders; along the wavy margin, tertiary veins tending to be percurrent or form inverted

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145 ‘V’s but with irregular course and spacing (Figure 69, 2). Quaternary veins (Figure 69, 2) in the excostal region and below sinus between secondary veins predominately percurrent, course straight or curved. Quinternary veins orthogonal reticulate, joining others to form imperfect areoles or incompletely enclose meshed, then giving rise to simple, linear or curved veinlets. Below the basal pair of secondary veins and peltate petiole base, 2 pairs of veins of tertiary order originating from primary veins, recurved and extending to the wavy leaf margin. Number of specimens examined. 26. Holotype. Eurylobum dentatum Lesquereux, Rept. U.S. Geol. Surv. Terr., vol.8 (Cret. And Tert. Fl.), 1883: p.88 = Eurylobum dentatum Schwarzwalder and Dilcher 1986 Paratypes. UF18047-14978, 14978’; 31625, 31625’; 31626; 31638, 31638’. Discussion. A larger number of specimens (56%, 42 of 75 specimens) collected from the Springfield locality, Nebraska, are assigned to either Eurylobum dentatum or Aspidiophyllum obtusum. The relationship of these two extinct genera with the modern family Platanaceae was indicated not onl y by characters of leaf architecture (Schwarzwalder and Dilcher, 1981; Schwarzwalder, 1986, 1991), but also by their cooccurrence with platanoid type of globular heads (infructescences, Figure 69, 3; Figure 70, 5-6) at the same locality. Aspidiophyllum Lesquereux emend. Schwarzwalder and Dilcher 1986 Generic diagnosis. See Schwarzwalder (1986, p.51, Ph. D. thesis). Aspidiophyllum obtusum (Lesquereux) Hongshan Wang comb. nov. (Figure 68, 1-6; Figure 71, 2; Figure 71, 4-5)

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146 “Sassafras” (Araliopsis) cretaceum var. obtusum Lesquereux, 1874, The Cretaceous Flora, p.80, pl. 7, Figure 2; p.80, pl. 8, Figure 1. “Sassafras” harkerianum Lesquereux, 1874, The Cretaceous Flora, p.81, pl. 6, Figures 34. “Sassafras” obtusum Lesquereux 1874, The Cretaceous Flora, p.80, pl. 7, Figure 3; p. 81, pl. 8, Figures 2-4. Aspidiophyllum cretaceum Newberry 1898, Late extinct floras of North America, p. 98, pl. 8, Figure 2. Specific diagnosis. Leaf three lobed. Apex of lobes rounded. Base asymmetrical, decurrent or sometimes slightly auricular. Petioles thin. Primary venation actinodromous; position of primary vein suprabasal, perfect. Secondary venation mixed brochidodromous and craspedodromous, but predominately brochidodromous; secondary vein thick, typically 4 to 5 pairs of secondary veins in the middle lobe, originating from medial primary vein at moderately acute angles, opposite or subopposite, uniformly or abruptly curved to join exmedial branches of super adjacent secondary veins to from one series of loops. Veins of tertiary or secondary order below the sinus and between the medial and lateral primary veins forming a series of inverted ‘V’s. Secondary venation typically brochidodromous in the lower leaf lamina and craspedodromous in the upper lamina; if craspedodromous, secondary veins terminate on the slightly wavy margin. Tertiary veins tending to be percurrent, convex or somewhat orthogonal reticulate but tending to form a composite intersecondary veins; quaternary veins orthogonal reticulate.

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147 Description. Leaf three lobed (Figure 68, 1-6). Leaf up to 12 cm long by 16 cm wide (Figure 68, 1. Length measured from apex of medial lobe to leaf base and width measured from the widest point of latera l lobes). Apex of lobes rounded. Base asymmetrical, decurrent or sometimes slightly auricular (Figure 71, 4-5). Petiole thin, up to 6 cm long (length measured from the point where lateral primary vein originated) by 1 mm wide. Primary venation actinodromous; primary vein moderate; position of primary vein suprabasal, perfect (Figure 68, 3-6). Secondary venation mixed brochidodromous (Figure 68, 2) and craspedodromous (Figure 68, 5), but predominately brochidodromous; secondary vein thick, typically 4 to 5 pairs of secondary vein in the middle lobe, originating from medial primary vein at moderate acute (±45º) angles, opposite or subopposite, uniformly or abruptly curved to join exmedial branches of super adjacent secondary veins to from one series of loops. Veins of tertiary or secondary order below sinus and between medial and lateral primary veins forming a series of inverted ‘V’s. Secondary venation typically brochidodromous at lower portion and craspedodromous on upper portion; when craspedodromous, secondary veins terminate on the slightly wavy margin. Tertiary veins tending to be percurrent, convex (middle portion of the vein curving away from the center of the leaf) or somewhat orthogonal reticulate but tending to form a composite intersecondary veins; quaternary veins orthogonal reticulate. Number of specimens examined. 16. Holotype. Aspidiophyllum obtusum Lesquereux 1874, The Cretaceous Flora, p.80, pl. 7, Figure 3; p. 81, pl. 8, Figures 2-4. Paratypes. UF18047-14976, 14976’; 14977; 31600; 31601; 31603; 31604; 31624.

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148 Discussion. Aspidiophyllum obtusum differs from other species of Aspidiophyllum in having fewer secondary veins on each lobe. As suggested by Schwarzwalder (1986), the genus Aspidiophyllum represents leaf forms are intermediate in many morphological characters between Eoplatanus and Credneria. Clade UNKNOWN Meiophyllum Hongshan Wang gen. nov. Meiophyllum expansolobum (Upchurch and Dilcher) Hongshan Wang comb. nov. (Figure 37, 1-8; Figure 64, 1-2) Description. Leaf, five-lobed, only basal portion of leaves observed. Petioles thin; thickened lamina structure present at the junction of petiole and lamina base. Primary venation basal actinodromous; primary veins stout to massive, multistranded; medial primary vein straight in course; inner lateral primary veins apically curved; outer primary veins apically curved or recurved. Veins of higher order not observed Number of specimens examined. 2. Paratypes. UF18038-31735; 31736. Discussion. Two basal portion of leaves observed from this locality. The thickened lamina structure at the junction of petiole (Figure 64, 1-2) and lamina base and basal actinodromous venation are the diagnostic characters that enable the assignment of the Pleasant Dale locality specimens to Meiophyllum expansolobum . Dicotylophyllum denticulatus Hongshan Wang sp. nov. (Figure 64, 6) Proteophyllum lanceolatum Frantisek Nemejc and Zlatko Kvacek, 1975, pp. 37-39, pl. 6, Figure 8

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149 Specific diagnosis. Lamina margin toothed, teeth small and numerous; apical angle of tooth acute, serration type convexconcave; tooth tiny, simple, apical portion curved distally, spacing regular; sinuses rounded. Primary venation pinnate; primary vein stout, straight. Secondary venati on festooned brochidodromous; secondary veins moderate in thickness, opposite; angle of divergence narrow or moderate acute, extending midway of distance from primary vein to margin to join super adjacent secondary vein to form an intercostal region, with long axis almost parallel to primary, then continuing to join exmedial branches of super adjacent secondary vein to form at least two more series of loops, with the first series of loops occupying 1/3 of distance from primary vein to margin Description. Only middle portion of leaf lamina observed (Figure 64, 6). Observed leaf lamina margin toothed; api cal angle of tooth acute, serration type convex (basal or lower side)-concave (apical side); tooth tiny, simple, apical portion curved distally, 10 teeth per cm, with regular spacing; sinuses rounded, sometime difficult to observe due to spacing of teeth; no veins obser ved in the teeth. Primary venation pinnate; primary vein stout, straight. Secondary venation festooned brochidodromous; secondary veins moderate in thickness, opposite; angle of divergence narrow or moderate acute ( 45 ), extending towards leaf margin to join super adjacent secondary vein to form an intercostal region, with long axis almost parallel to primary vein (the ratio of long and short axis 3:1), then continuing to join exmedial branches of super adjacent secondary vein to form at least two series of loops, with the first series of loops extending 1/3 of distance from primary vein to margin. No veins of higher order observed. Number of specimens examined. 1.

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150 Holotype. UF18038-31731. Derivation of Epithet. Latin, “denticulatus” means “with small teeth,” referring to the tiny teeth on margin. Discussion. The venation pattern of this species is distinct from all other midCretaceous angiosperm leaf fossils from the Dakota Formation. One specimen described by Frantisek and Kvacek (1975) was misidentified as Proteophyllum lanceolatum . The following characters: (1) festooned brochi dodromous venation; (2) secondary veins extending halfway of distance from primary vein to margin; and (3) secondary veins joining exmedial branches of super adjacent secondary veins to form at least two series of loops, with the first series of loops occupying 1/3 of distance from primary vein to margin, giving an appearance of “acrodromous secondary venation pattern” are diagnostic features for this species. The leaf architecture of Dicotylophyllum denticulatus is similar to some members of Myrtaceae, especially Syzygium , for example, Syzygium jambos (L.) Alston (Klucking, 1988; Yu and Chen, 1990); Syzygium longipes (Klucking, 1988), and Syzygium tripernnatum (Klucking, 1988), etc. because both have looping arches forming sinuous intramarginal vein. Dicotylophyllum denticulatus differs from all these modern species because it has relatively strong secondary veins that form first order loops which only possess 1/3 of the distance from primary vein to margin and with long axes almost parallel to primary vein, and more importantly, its margin is toothed instead of entire. Quercophyllum tenuinerve Fontaine 1889 (Figure 64, 8) Quercophyllum tenuinerve Fontaine, 1889, p. 308, pl. 149, Figures 6-7.

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151 Quercophyllum tenuinerve Fontaine, 1977, Hickey and Doyle, p. 25, Figure 17. Emended specific diagnosis. Leaf margin toothed. Primary venation pinnate. Primary vein thin. Secondary venation craspedodromous; secondary veins thin, course slightly curved, each extending to and terminating in a tooth, accompanied by looping veins of tertiary order; apical angle of tooth acute; serration type convex (basal side)straight or convex (apical side); sinuses rounde d; tooth apex mucronata or with a gland; tooth spacing irregular. Description. Observed (Figure 64, 8) lamina 2 cm long by 1.5 cm wide, margin toothed, leaf texture appearing to be very thin. Primary venation pinnate; primary vein thin. Secondary venation craspedodromous; secondary veins thin, course slightly curved, each extending to and terminating in a tooth, accompanied by looping veins of third order; apical angle of tooth acute; serration type convex (basal side)-straight or convex (apical side); sinuses rounded; tooth apex mucr onata (probably a vein protruding to act as a mucro); tooth irregularly spaced. Number of specimens examined. 1. Paratype. UF18038-31732. Discussion. The specimen from the Pleasant Dale locality is the same as that illustrated and described by Hickey and Doyle (1977). The diagnostic features of these leaves are thin lamina, craspedodromous secondary venation, and irregularly spaced and doubly convexed tooth with a larger glandular area near the apex. However, FontaineÂ’s illustrations show that this species seems to have regularly spaced teeth (Fontaine, 1889). Clade UNKNOWN ? Menispermites sp.

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152 (Figure 68, 7) Specific diagnosis. Leaf base cordate. Primary venation pinnate; primary vein moderate in thickness, multistranded, course straight. Secondary venation brochidodromous; secondary vein moderate, multistranded, and decurrent on primary vein. Description. Leaf base cordate; shape unknown; observed margin entire. Observed leaf lamina 4 cm long by approximately 2.5 cm wide. Primary venation pinnate; primary vein moderate in thickness, multistranded, course straight. Secondary venation brochidodromous; secondary vein moderate, multistranded, decurrent on primary vein; angle of divergence varying from right of first basal pair of secondary veins to moderate acute (±50º) of second pair and above. Veins of higher order not observed. Number of specimens examined. 1. Type. UF18047-31693. Discussion. This species resembles Menispermites borealis Heer? (Newberry, 1895, p.84, pl. 50, Figures 1-6), Menispermites obtusiloba (Lesquereux, 1874, p.95, pl. 22, Figure 1) in leaf shape and primary venation pattern. Because higher order venation patterns are not preserved on both specimens from Newberry’s collection and the Springfield locality, Nebraska, further comparison between them is not available. Courtland I Locality, Minnesota MAGNOLIIDS MAGNOLIALES Jarzenia Hongshan Wang gen. nov. Generic diagnosis. Leaf simple; margin entire. Primary venation pinnate; primary vein, straight, multistranded. Secondary venation brochidodromous; secondary,

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153 subopposite, moderate in thickness relative to primary vein, originating from primary vein at moderate acute angles, with lowest one or two pairs more acute than pairs above; secondaries straight at 2/3 distance to the margin and then curved gradually to joining exmedial branches of superadjacent secondaries at obtuse angles to form loops; intercostal and excostal region not well defined; two basal thin secondaries originating at extreme base of lamina and runs very closely along the margin. Intersecondaries present, extending half distance to the margin before intergrading or branching to form tertiaries. Tertiaries moderate, more or less sinus in course, percurrent or reticulate. Derivation of generic name. In honor of David M. Jarzen and in recognization of his contributions to the curation of the paleobotany collections at the Florida Museum of Natural History. Discussion. Newberry (1895) and Lesquereux (1892) described many Cretaceous specimens from the Amboy Clay and Dakota Formation and assigned them to “ Andromeda ” parlatorii Heer. However, the modern genus name Andromeda (Ericaceae) is inappropriate and the species epithet is already used by specimens from Braun’s Ranch Locality of Kansas based on the rules of priority for species names. Thus, the new genus is set up for specimens with the following characters: Leaf simple; margin entire, primary vein multistranded; secondary venation brochidodromous, secondary vein originating from primary vein at moderate acute angles, with lowest one or two pairs more acute than pairs above; intercostal and excostal region not well defined; two basal thin secondaries originating at extreme base of lamina and runs very closely along the margin; intersecondaries present. Tertiaries moderate, more or less sinus in course,

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154 percurrent. Quaternary veins intergrading with veinlets; areoles with incompletely closed meshes. Jarzenia kanbrasota Hongshan Wang sp. nov. (Figure 50, 1-6; Figure 50, 9-10) “Andromeda” parlatorii Heer, Lesquereux, 1892, pp.115-116, pl.19, Figure 1; pl.52, Figure 6. “Andromeda” parlatorii Heer, var. longifolia , Lesquereux, 1892, p.116, pl.64, Figure 19. “Andromeda” parlatorii Heer, Newberry, 1895, Flora of the Amboy clays, p.120, pl. 31, Figures 1-7; pl. 33, Figures 1,2,4,5. Specific diagnosis. Leaf oblanceolate or narrow obovate; base acute, normal; margin entire; petiole normal. Primary venation pinnate; primary vein, straight, multistranded. Secondary venation brochidodromous; secondary, subopposite, moderate in thickness relative to primary vein, originating from primary vein at moderate acute angles, with lowest one or two pairs more acute than pairs above; secondaries straight at 2/3 distance to the margin and then curved gradually to joining exmedial branches of superadjacent secondaries at obtuse angles to form loops; intercostal and excostal region not well defined; Two basal thin secondaries originating at extreme base of lamina and runs very closely along the margin. Intersecondaries present, extending half distance to the margin before intergrading or branching to form tertiaries. Tertiaries moderate, more or less sinus in course, percurrent, angle of origin predominately right-right (RR) or acute-obtuse (AO); Primary-tertiary vein a ngle oblique, decreasing outward and upward. Quaternary veins moderate in thickness relative to tertiaries, random and sinuous in

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155 course, intergrading with veinlets. Areoles with incompletely closed meshes. Veinlets simple or branched once. Description. Leaf oblanceolate or narrow obovate, L/W 2-3, up to 10 cm long (estimated maximum length) by 2.2 cm to 4.8 cm wide; apex possibly obtuse; base acute, normal; margin entire; petiole normal, up to 2.7 cm long by 2 mm wide. Primary venation pinnate; primary vein stout (up to 1.5 mm wide near base and 1mm wide at the middle part of the lamina), straight, multistranded. Secondary venation brochidodromous; secondary vein at least 10 pairs, subopposite, moderate in thickness relative to primary vein, originating from primary vein at moderate acute angles (45 to 65 ), with lowest one or two pairs more acute than pairs above; secondaries straight at 2/3 distance to the margin and then curved gradually to joining exmedial branches of superadjacent secondaries at obtuse angles to form loops; intercostal and excostal region not well defined; two basal thin secondaries originating at extreme base of lamina and runs very closely along the margin (less than 0.5 mm to the margin). Intersecondaries present, no more than one per intercostal region, extending half distance to the margin before intergrading or branching to form tertiaries. Tertiaries moderate, more or less sinus in course, percurrent, angle of origin predominately right-right (RR) or acute-obtuse (AO); primary-tertiary vein angle oblique, decreasing outward and upward. Quaternary veins moderate in thickness relative to tertiaries, random and sinuous in course, intergrading with veinlets. Areoles with incompletely closed meshes. Veinlets simple or branched once. Number of specimens examined. 7. Holotype. UF18267-24824, 24824Â’

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156 Paratypes. UF18267-16599, 16599Â’; 24837-2, 24837-2Â’; 26144; 26132; 16571. Derivation of epithet. Referring to the occurrence of this species in Kansas, Nebraska, and Minnesota. Discussion. This species resembles New Genus A (Upchurch and Dilcher, 1990) in gross leaf shape. Among the entire-margined leaves from the Courtland I locality, the new species is similar to Setterholmia rotundifolia but it differs from it in having oblanceolate or narrow obovate shape, more cuneate leaf base, lowest one or two pairs of secondary veins originating at more acute angles than those above, intercostal regions not well defined, tertiary veins less percurrent, and glands apparently lacking. Jarzenia reticulatus Hongshan Wang sp. nov. (Figure 53, 1-3) Specific diagnosis. Leaf narrow oblong, margin entire. Primary venation pinnate; primary vein stout, multistranded. Secondary venation festooned brochidodromous; secondaries thin relative to primary vein, angle of divergence uniform, approximately; secondary vein spacing irregular, subopposite to alternate, straight in course but abruptly curved very close to the margin to join exmedial branches of superadjacent secondaries at obtuse angles to form secondary arches which enclose elongate, not well defined intercostal regions; the secondary arches are enclosed by tertiary and quaternary arches. Intersecondaries present. Tertiaries moderate relative to secondaries, originating from secondary vein at predominately right angles, orthogonal reticulate, sinuous in course, sometime intergrading with quaternary veins. Quaternary veins moderate, orthogonal.

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157 Description. Leaf narrow oblong, observed lamina 8 cm long by 2.4 cm wide, L/W at least 3/1; apex and base missing; observed margin entire. Primary venation pinnate; primary vein stout, multistranded. Secondary venation festooned brochidodromous; secondaries thin relative to primary vein, angle of divergence uniform, approximately 45 ; secondaries at least 12 pairs observed with irregular spacing (>5 mm), subopposite to alternate, straight in course but abruptly curved very close to the margin to join exmedial branches of superadjacent secondaries at obtuse angles to form secondary arches which enclose elongate, not well defined intercostal regions; the secondary arches are enclosed by tertiary and quaternary arches. Intersecondaries present. Tertiaries moderate relative to secondaries, originating from secondary vein at predominately right angles, orthogonal reticulate, sinuous in course, sometime intergrading with quaternary veins. Quaternary veins moderate, orthogonal. Veins of higher order not observed. Number of specimens examined. 1. Holotype. UF18267-16614, 16614’ (part and counterpart). Derivation of Epithet. Latin, “reticulatus” means “netlike,” referring to orthogonal reticulate tertiary and quaternary veins. Discussion. Jarzenia reticulatus is similar to Setterholmia deleta in secondary venation patterns but it differs from it in having narrow oblong lamina shape, more secondaries with not well-defined intercostal regions, orthogonal reticulate tertiary and quaternary veins. Jarzenia reticulatus differs from J. kanbrasota in narrow oblong leaf shape and orthogonal reticulate tertiary and quaternary veins. LAURALES

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158 cf. LAURACEAE Wolfiophyllum Hongshan Wang gen. nov. Wolfiophyllum pfaffiana Hongshan Wang sp. nov. (Figure 56, 8-12; Figure 58, 3-5, Figure 58, 8-9; Figure 60, 2-3) Generic and specific diagnosis . See systematics, Hoisington III locality, Kansas. Description. Leaflet? shape narrow oblong to lorate, L/W 3 to 6, lamina 1.5 to 2 cm wide by 4.5 to 12 cm long. Apex predominantly acute, occasionally obtuse. Base predominantly asymmetrical; acute, decurrent. Petiole normal, short, about 3 mm long by 2 mm wide. Margin entire. Primary venation pinnate; primary vein strong, course straight or curved, multistranded. Secondary venation eucamptodromous; at least 10 pairs per lamina; secondary veins originating from primary veins at acute angles (45 ), decurrent; course uniformly curved. Intersecondary veins present, simple. Tertiary veins reticulate. Veins of higher order not observed. Number of specimens examined. 26. Paratypes. UF15706-16563; 16568, 16568Â’; 16572; 16606; 16613; 21210; 21218, 21218Â’; 24838; 24857, 24857Â’; 24869, 24869Â’. Discussion. See systematics, Hoisington III locality, Kansas. Rogersia kansense Hongshan Wang sp. nov. (Figure 50, 7; Figure 51, 11-13; Figure 51, 15-16; Figure 60, 4) Description. Leaf attachment opposite. Leaf shape lorate to linear, L/W >6, lamina 0.5 to 1.3 cm wide by 5 to 13 cm long (estimated maximum length). Leaf base symmetrical, petiole normal, 2 to 10 mm long by 1 to 2 mm wide. Margin entire.

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159 Primary venation pinnate; primary venation strong, straight or slightly curved. Secondary venation festooned brochidodromous; secondary veins thin, decurrent on primary vein; originating from primary vein at acute (45 ) angles and extending in straight course to join superadjacent secondary veins very close to the margin to form two series of loops. Intersecondary veins absent. Tertiary veins predominantly percurrent. Number of specimens examined. 38. Paratypes. UF16706-20671; 6576, 16576Â’; 21194, 21194Â’; 24845; 24856; 24856; 24848. Discussion. See systematics, Hoisington III locality, Kansas. Setterholmia Hongshan Wang gen. nov. Generic diagnosis. Leaf simple; margin entire; petiole normal, stout. Primary venation pinnate; primary vein stout, straight, multi-stranded. Secondary venation brochidodromous; secondaries thick, multi-stranded, abruptly curved very close to margin and looping with super adjacent secondaries or exmedial branches of secondaries at right or obtuse angles; secondary arches prominent, always enclosed by a series of tertiary order loops in the extremely narrow excostal region; intercostal and excostal region very distinctive. Tertiaries percurrent. Quaternary veins thin, arising from tertiaries at right angles, tending to be transverse and parallel to secondaries in course. Quinternary veins thin, randomly arranged. Areoles imperfectly developed, shape irregular, size medium. Derivation of generic name. In honor of Dale R. Setterholm and in recognition of his contributions to the collection of Courtland I locality specimens and the research on the Cretaceous stratigraphy of Minnesota.

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160 Discussion. Lesquereux (1874, 1892) assigned similar Dakota Formation specimens to the extant genus Diospyros of Ebenaceae. However, the following characters (1) thick secondaries; (2) multistranded primary and secondaries (3) well defined intercostal and extremely narrow excostal regions (especially on the distal portion); (4) thick tertiaries predominately alternately percurrent; and (5) possible oils glands on veins and areoles of one species show that the assignment to Diospyros in the Ebenaceae is incorrect. The new genus, Setterholmia , is set up for those Dakota Formation angiosperm fossil leaves which possess the following diagnostic characters: simple leaf with entire margin; multistranded primary and secondary veins; brochidodromous secondary venation with very distinctive intercostal and excostal regions; and percurrent tertiary veins. Setterholmia rotundifolia (Lesquereux) Hongshan Wang comb. nov. (Figure 49, 2-7; Figure 49, 9-10) “Diospyros” rotundifolia Lesquereux 1874, Contributions to the fossil flora of the Western Territories-part 1, the Cretaceous flora: U.S. Geological and Geographical Survey of the Territories Report 6, p.89, pl.30, Figure 1. “Diospyros” rotundifolia Lesquereux 1892, U.S. Geological Survey Monograph 17, p.112, pi.17, Figures 8-11. Specific diagnosis. Leaf simple; margin entire, reinforced; petiole normal, short, stout. Primary venation pinnate; primary vein stout, straight, multi-stranded. Secondary venation brochidodromous; secondaries origin ating from primary at wide angles; secondaries thick, multi-stranded, abruptly curved very close to margin and looping with super adjacent secondaries or exmedial branches of secondaries at right or obtuse angles;

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161 secondary arches prominent, always enclosed by a series of tertiary order loops in the extremely narrow excostal region; intercostal and excostal region very distinctive; secondaries decurrent, very wide near primary vein but thin noticeably as they near the leaf margin. Intersecondaries present, simple. Tertiaries percurrent, angles of origin predominately right-right (RR), convex or re troflexed; primary-tertiary vein angle decreases upward, origin of tertiaries predominately alternate. Quaternary veins thin, arising from tertiaries at right angles, tending to be transverse and parallel to secondaries in course. Quinternary veins thin, randomly arranged. Areoles imperfectly developed, shape irregular, size medium. Excostal veins looped, apically oriented. Marginal ultimate veins loped. Oil glands present, preserved on different order of veins and areoles. Description. Leaf suborbiculate to elliptic, L/W 1.2 to 2.5, 3 to 8 cm (estimated minimum and maximum length) long by 2 to 6 cm wide; apex mucronate (Figure 49, 2-3; 2 mm wide by 1 mm high); base normal obtuse to rounded; margin entire, reinforced; petiole normal, short and stout. Primary venation pinnate; primary stout, straight, multistranded. Secondary venation brochidodromous; up to 9 pairs, opposite to sub-opposite, originating from primary at wide angles; secondaries thick, multi-stranded, abruptly curved very close to margin (1/20 distance from primary vein to leaf margin) and looping with super adjacent secondaries or exmedial branches of secondaries at right or obtuse angles, forming prominent intercostal regions; secondary arches prominent, always enclosed by a series of tertiary order loops in the extremely narrow excostal region; intercostal and excostal region very distinctive; occasionally secondaries bifurcating at 1/2 to 2/3 distance to leaf margin; secondaries often conspicuous on one part,

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162 occasionally on both part and counterpart; secondaries thin noticeably as they near the leaf margin; two very thin basal secondaries (Figure 49, 10) originating from the extreme base of lamina, joining exmedial branches in tertiary order from superadjacent secondaries to form a series of loops which runs along the basal margin, sometimes these loops may be enclosed by another series of thinner outer loops. Intersecondaries present, simple. Tertiaries percurrent, angles of or igin predominately right-right (RR), convex or retroflexed; primary vein-tertiary vein angle decreases upward, origin of tertiaries predominately alternate. Quaternary veins, th in, arising from tertiaries at right angles, tending to be transverse and parallel to secondaries in course. Quinternary veins thin, randomly arranged. Areoles imperfectly developed, shape irregular, size medium; no veinlets (may be closed venation) not observed. Excostal veins looped, apically oriented. Marginal ultimate veins loped. Possible oil glands present, dark brown in color, preserved on different order of veins and areoles. Number of specimens examined. 10. Holotype. Setterholmia rotundifolia Lesquereux, 1874, Contributions to the fossil flora of the Western Territories-part 1, the Cretaceous flora: U.S. Geological and Geographical Survey of the Territories Report 6, p.89, pl.30, Figure 1. Paratypes. UF18267-16581, 16581Â’; 16582, 16582Â’; 16583; 16586, 16586Â’; 24820; 20141, 20141Â’. Discussion. Simple leaf, entire margin, brochidodromous pinnate venation with basal pairs originating at lower angle than those above, alternate percurrent tertiaries, and mesophyll cells suggest that the new combination is closely related to Laurales (Hickey and Wolfe, 1975). Of the extant Lauraceae, the venation pattern of Setterholmia

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163 rotundifolia is most similar to Endiandra bullata (Allen) Kostern (Klucking, 1987) in leaf shape, secondary vein looping behavior on the distal portion (which defines distinct intercostal and extreme narrow excostal regions). Setterholmia rotundifolia is similar to that of Ocotea tarpotina (Meissn.) Mez. (Klucking, 1987) in secondary vein looping pattern near the apex, intersecondary vein pattern, alternate percurrent tertiaries, and having short, weak, vestigal acrodromal basal secondaries. Setterholmia callii Hongshan Wang sp. nov. (Figure 49, 1; Figure 49, 8) Specific diagnosis. Leaf simple; margin entire, reinforced; petiole normal, stout. Primary venation pinnate; primary vein stout, straight, multi-stranded. Secondary venation brochidodromous; secondaries originating from primary at moderate angles, with middle to upper secondaries arising somewhat more obtuse than basal secondaries; secondaries thick, multi-stranded, abruptly curved very close to margin and looping with super adjacent secondaries or exmedial branches of secondaries at right or obtuse angles; secondary arches prominent, always enclosed by a series of tertiary order loops in the extremely narrow excostal region; intercostal and excostal region very distinctive; secondaries decurrent, very wide near primary vein but thin noticeably as they near the leaf margin; secondaries clustered near base. Tertiaries percurrent, angles of origin predominately right-right (RR), convex or retr oflexed; primary vein-tertiary vein angle decreases upward, origin of tertiaries predominately alternate. Excostal veins looped, apically oriented. Marginal ultimate veins loped. Description. Leaf suborbiculate to elliptic, L/W 1.2 to 2.5, 5 cm long by 3.6 cm wide; apex appearing to be emarginate (Figure 49, 1); base normal cuneate (Figure 49, 1)

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164 obtuse to rounded (Figure 49, 8); margin entire, reinforced; petiole normal, stout, up to 1.1 cm long by 1 mm. Primary venation pinnate; primary stout, straight, multi-stranded. Secondary venation brochidodromous; up to 9 pairs, opposite to sub-opposite, originating from primary at moderate angles, with middle to upper secondaries arising somewhat more obtuse than basal secondaries; secondaries thick, multi-stranded, abruptly curved very close to margin (1/20 distance from primary vein to leaf margin) and looping with super adjacent secondaries or exmedial branches of secondaries at right or obtuse angles, forming prominent intercostal regions; secondary arches prominent, always enclosed by a series of tertiary order loops in the extremely narrow excostal region; intercostal and excostal region very distinctive; occasionally secondaries bifurcating at 1/2 to 2/3 distance to leaf margin; base of secondaries wide, decurrent; secondaries clustered near base (almost half secondaries in one-third basal part of the lamina). Tertiaries percurrent, angles of origin predominately right-right (RR), convex or retroflexed; primary veintertiary vein angle decreases upward, origin of tertiaries predominately alternate. Quaternary veins, thin, arising from tertiaries at right angles, tending to be transverse and parallel to secondaries in course. Excostal veins looped, apically oriented. Marginal ultimate veins loped. Number of specimens examined. 3. Holotype. UF 18267-16580, 16580Â’ Paratypes. UF18267-20332, 20332Â’; 24821, 24821Â’. Derivation of epithet. In honor of Victor B. Call a nd in recognition of his help in the collection of Dakota specimens.

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165 Discussion. Setterholmia callii is similar to Setterholmia rotundifolia in many features but it differs from it in having clustered secondary veins near leaf base (almost half secondary veins clustered in one-third basal portion of leaf lamina) and the absence of intersecondary veins. Setterholmia deleta (Lesquereux) Hongshan Wang comb. nov. (Figure 60, 7-8) “Salix” deleta Lesquereux, 1892, U.S. Geological Survey Monograph 17, p.49, pl.3, Figure 8. Specific diagnosis (emended) . Lamina narrow elliptic; apex attenuate; base acute and decurrent; margin entire. Primary venation pinnate; primary stout, multistranded. Secondary venation festooned brochidodromous; secondaries moderate, opposite to subopposite, multistranded, decurrent, spacing irregular, diverging at moderate acute angles with the lowest pair more acute than pairs above; curved abruptly very close to margin, joining superadjacent secondaries at predominately obtuse (occasionally at right angles), with flattened brochidodromous arches at the attenuate apex; some secondaries either extending directly to secondary arches formed by two adjacent secondaries or branching in the intercostal region into tertiaries; intersecondaries common, almost the same thickness as that of secondaries; a series of secondary arches formed by the lowermost secondaries running along basal portion of lamina. Intercostal tertiaries tending to be percurrent, tertiaries thick relative to secondary vein, angle of origin predominately right-right, occasionally obtuse-right, course predominately convex, oblique to the primary vein, with primary-tertiary vein angle decreasing upward and

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166 outward, arrangement predominately alternate. Quaternary veins thick, predominately arising at right angles from tertiaries, course irregular. Description. Lamina slightly asymmetrical, narrow elliptic, L/W 2.8; lamina 6.6 cm long by 2.4 cm wide; apex attenuate with tip missing; base acute and decurrent, most of petiole missing; margin entire, with marginal veins. Primary venation pinnate; primary stout, multi-stranded. Secondary venation festooned brochidodromous; secondaries moderate, at least 15 pairs (those in uppermost attenuate apex not counted), opposite to subopposite, spacing irregular, multistranded, decurrent on the primary, diverging at moderate acute angles (45º to 65º) with the lowest pair more acute than pairs above; curved abruptly near margin, joining superadjacent secondaries at predominately obtuse but occasionally at right angles, with flattened brochidodromous arches at the attenuate apex; some secondaries either extending directly to secondary arches formed by two adjacent secondaries (not forming arches) or branching in the intercostal region into tertiaries; intersecondaries common, almost the same thickness as that of secondaries; a series of secondary arches formed by the lowermost secondaries. Intercostal tertiaries tending towards percurrent, tertiaries thick relative to secondary vein, angle of origin predominately right-right (RR), occasionally obtuse-right (OR), course predominately convex, oblique to the primary vein, with primary-tertiary angle decreasing upward and outward, arrangement predominately alternate, close (less than 0.5cm between tertiaries). Quaternary veins thick, predominately arising at right angles from tertiaries, course irregular. Veins of higher order and ultimate veins poorly preserved. Number of specimens examined. 2.

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167 Holotype. Setterholmia deleta Lesquereux, 1892, U.S. Geological Survey Monograph 17, p.49, pl.3, Figure 8. Paratypes. UF18267-16564, 16564Â’. Discussion. Lesquereux's (1892) assignment of this species to modern genus Salix seems to be incorrect because this fossil species doesnÂ’t possess characters such as the salicoid tooth, and the festooned brochidodromous venation of Setterholmia deleta is not found in any members of Salix, including those entire margined Arctic species (Ramirez and Cevallos-Ferriz, 2000). The following characters such as narrow elliptic leaf shape, multi-stranded primary and secondaries, festooned brochidodromous secondary venation, very common intersecondaries, and relatively poor differentiation of vein order indicate a possible relationship with Lauraceae. Manchesterii Hongshan Wang gen. nov. Generic diagnosis. Leaf simple. Base acute, decurrent; margin entire with mechanical reinforcement. Primary vein massive. Secondary venation pinnate, festooned brochidodromous; secondaries thin relative to primary vein, numerous; arrangement on primary vein sub-opposite, regularly spaced; secondaries decurrent on primary vein, originating at wide acute angles, uniformly curved or undulate in course, joining super-adjacent secondaries at obtuse angles, exmedially brochidodromous arches rectilinear; intersecondaries very common, one per intercostal region, with one tertiary vein arising from primary vein between and parallel to secondary and intersecondaries. Intercostal tertiary venation reticulate; tertiaries originating at variable angles from secondary and intersecondaries and at wide acute angles from the primary; excostal tertiaries reticulate, anastomosing with secondaries, approximately at right angles to leaf

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168 margin. Intercostal quaternary veins irregularly reticulate; excostal quaternary venation randomly reticulate; quinternary venation dominantly rectangular, with ultimate veins originating from quinternary veins and branching once appearing to form open venation pattern. Quaternary and quinternary feed directly into a broad marginal area. Derivation of generic name. In honor of Steven R. Manchester and in recognization of his contributions to angiosperm paleobotany. Discussion. The new genus is set up for those Dakota Formation angiosperm leaves with the suite of following characters: leaf simple with entire margin; secondary venation festooned brochidodromous; secondary veins relatively thin and numerous; secondary veins originating at very wide angles from primary vein; intersecondary and inter-intersecondary veins common; and irregularly reticulate higher order veins. Manchesterii macrophylla (Lesquereux) Hongshan Wang comb. nov. (Figure 52, 1-2; Figure 52, 4-6) “ Ficus ” macrophylla Lesquereux, 1892, U.S. Geological Survey Monograph 17, p.76, pl.11, Figure 1. Specific diagnosis. Same as for genus. Description. Leaf, simple, narrow oblong to lorate; L/W ratio at least 5:1, lamina 25 cm long (estimated maximum leaf length) by 5 cm wide. Apex possibly attenuate. Base acute, decurrent; margin entire, with a bumpy edge resulting from 0.25 mm extensions of apparent glandular thickenings, margin with mechanical reinforcement. Primary vein massive, 3 mm wide at middle of the observed specimen, straight. Secondary venation pinnate, brochidodromous; secondaries thin relative to primary vein, numerous; arrangement on primary vein sub-opposite, regularly spaced; secondaries

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169 decurrent on primary vein, originating at wide acute angles (65º to 80º), uniformly curved or undulate in course, joining super-adjacent secondaries at obtuse angles, exmedially brochidodromous arches rectilinear; Intersecondaries common, one per intercostal region, with one tertiary vein arising from primary vein between and parallel to secondary and intersecondaries, extending ¼ to 1/3 distance from primary vein to leaf margin. Intercostal tertiary venation reticulate; tertiaries originating at variable angles from secondary and intersecondaries and at wide acute angles from the primary; excostal tertiaries reticulate, anastomosing with secondaries, approximately at right angles to leaf margin. Intercostal quaternary vein irregularly reticulate; excostal quaternary venation randomly reticulate; quinternary venation dominantly rectangular, or occasionally ultimate veins originating from quinternary veins and branching once appearing to form open venation pattern. Quaternary and quinternary feed directly into a broad marginal area to reinforce the margin (marginal reinforcement approximately 0.3 mm wide), giving an appearance of glands densely arranged at the leaf margin that forms a bumpy edge on leaf margin. Number of specimens examined. 2 (16 from Pleasant Dale locality, Nebraska). Holotype. Manchesterii macrophylla Lesquereux, 1892, U.S. Geological Survey Monograph 17, p.76, pl.11, Figure 1. Paratypes. UF18267-16600, 16600' (part and counterpart); UF18844-32485. Discussion. Manchesterii macrophylla can be distinguished from other Dakota Formation angiosperm fossils by the following distinctive features: very large and entire margined leaf, massive primary vein and relatively thin secondaries, numerous secondaries diverging at very wide angles, secondaries curved near margin to form at

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170 least two series of loops, common intersecondary and inter-intersecondaries, reticulate tertiary and higher order veins forming square areoles, and quaternary and quinternary feed directly into a broad marginal area to reinforce the margin. Manchesterii macrophylla is similar to some extant species of Eurya of the Theaceae, for example, Eurya hainanensis Kob., Eurya impressinervis Kob., and Eurya macartheyi Champ. (Yu and Chen, 1990) and some member of extant Moraceae, for example , Ficus glaberrima Bl.. and Pseudostreblus indica Bur. (Yu and Chen, 1990) in secondary venation pattern, common intersecondaries, and brochidodromous secondaries enclosed by loops of higher order veins but it differs from them in leaf shape, lacking of teeth, massive primary vein, and reticulate tertiary and quaternary veins. Manchesterii macrophylla is similar to some other member of Ficus , for example, Ficus elastica Roxb (Yu and Chen, 1991), F. benjamina L. (Yu and Chen, 1991) in lower order (primary and secondary) venation pattern but it differs from them in higher order venation patterns. The suite of characters of Manchesterii macrophylla is not observed in any extant members of Ficus . Manchesterii macrophylla is most similar to Cryptocarya filicifolia (Kosterm.) Kosterm. (Klucking, 1987) and Litsea iteodaphne Nees. (Klucking, 1987) in that both have obtuse angle of secondary vein divergence, irregular intercostal veins, continuous looping territories along the margin but it differs from them in leaf shape, strong intersecondaries, presence of inter-intersecondaries, and strongly structurally reinforced leaf margin. Considering the entire margin a nd leaf shape, irregularity of tertiary and higher order vein, intergrading between higher order veins, Manchesterii macrophylla is more closely related to the Lauraceae rather than the Theaceae or Moraceae.

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171 Crassidenticulum Upchurch and Dilcher 1990 Crassidenticulum cracendentis Hongshan Wang sp. nov. (Figure 59, 1-5) Specific diagnosis. Leaf thin, often tending to break apart, narrow oblong. Margin toothed, serrations typically straight-straight (B-2) or occasionally convexstraight (B-1), regularly spaced, sinus smooth; apical angle acute; glands occurring on the teeth as glandular thickenings embedded into the teeth. Primary venation pinnate; primary vein stout, straight, multistranded. Secondary venation semicraspedodromous; secondaries very thin relative to primary vein, regularly spaced; secondaries alternate, strongly decurrent on the primary vein; secondari es originating from primary vein at wide acute angles, curved abruptly at 1/3 distance to the margin, joining exmedial branches of superadjacent secondaries or superadjacent intersecondaries at obtuse angles, forming two series of secondary arches in the excostal region; occasionally, secondaries bifurcating once very close to primary vein, one branch extending a distance very close to the margin while the other one as intersecondary vein branching at half distance to the margin to form tertiaries in the intercostal region. Intersecondaries present, one in per intercostal region, somewhat irregular in course, extending ¼ distance to the margin before joining secondary vein. Tertiaries moderate relative to secondaries, interspersed from primary vein, extending half distance to the margin before intergrading with quaternary veins. Quaternary veins moderate, anastomosing with tertiary, intersecondary and secondaries irregularly. Quinternary veins moderate, randomly reticulate; areoles imperfect, meshes of irregular shape, variable in size but predominately medium. Glands

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172 innervated from veins branching from exmedially looping tertiaries extending toward the margin and branching to form one extension to the gland and one to the sinus. Description. Only middle portion of leaves observed. Leaf thin, tending to break apart, narrow oblong (L/W >2). Observed leaf lamina 9 cm long by 3.5 to 5.2 cm wide; apex and base missing; Observed leaf margin toothed, serrations are approximately 2 mm long by less than 1 mm wide, typically straight-straight (B-2) or occasionally convexstraight (B-1), regularly spaced, sinus smooth; serrate axes inclined to the tangent of leaf margin at an angle of approximately 45 ; apical angle acute; glands occurring on the teeth as glandular thickenings embedded into the teeth. Primary venation pinnate; primary vein stout, straight, multistranded. Secondary venation semicraspedodromous; secondaries very thin relative to primary vein, regularly spaced; secondaries alternate, strongly decurrent on the primary vein; secondari es originating from primary vein at wide acute angles (65º to 80 ), curved abruptly at 1/3 distance from primary vein to the margin, joining exmedial branches of superadjacent secondaries or superadjacent intersecondaries at obtuse angles, forming two series of secondary arches in the excostal region; occasionally, secondaries bifurcating on ce very close to primary vein, one branch extending a distance very close to the margin while other one as intersecondary vein branching at half distance to the margin to form tertiaries in the intercostal region. Intersecondaries present, one in per intercostal region, somewhat irregular in course, extending ¼ distance to the margin before joining secondary vein. Tertiaries moderate relative to secondaries, interspersed from primary vein, extending half distance to the margin before intergrading with quaternary veins. Quaternary veins moderate, anastomosing with tertiary, intersecondary and secondaries irregularly. Quinternary

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173 veins moderate, randomly reticulate; areoles imperfect, meshes of irregular shape, variable in size but predominately medium ( 0.1 to 0.3 mm). Veinlets indistinct. Glands innervated from veins branching from exmedially looping tertiaries extending toward the margin and branching to form one extension to the gland and one to the sinus; glands may be deciduous. Number of specimens examined. 3. Holotype. UF18267-16591, 16591’. Paratypes. UF18267-16598, 16598’; 24818. Derivation of Epithet. Latin, “cracens” means “neat” and “dentis” means “tooth,” referring to the beautiful teeth on leaf margin. Discussion. Though only fragmentary specimens are observed from this locality, Crassidenticulum cracendentis possesses the following diagnostic characters which are different from all other Dakota Formation angiosperm leaf megafossils: teeth with glandular heads (possibly hydathodes) whic h may be deciduous and unique tooth type (veins branching from exmedially looping tertiaries extending toward the margin and branching to form one extension to the gland and one to the sinus), stout and multistranded, semicraspedodromous secondary venation, intergrading between secondary and higher order veins. Densinervum Upchurch and Dilcher 1990 Densinervum kaulii Upchurch and Dilcher 1990 (Figure 60, 1; Figure 60, 5-6; Figure 60, 9-10) Densinervum kaulii Upchurch and Dilcher 1990, plate 5, figures 1-6; text figure 5; p. 1718.

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174 Generic diagnosis. See Upchurch and Dilcher (1990). Description. Lamina variable from very wide ovate to narrow ovate, L/W 1 to 2.3, lamina 3.1 to 7 cm long (observed length) by 3.2 to 4.1 cm wide; lamina divided for less than 1/10 of its length; base cuneate or obtuse cuneate; margin entire with structural reinforcement; petiole distinct, approximately 1.9 cm long, with very narrow decurrent wings of laminar tissue along each side, inflated at its base. Primary venation pinnate; primary vein moderate, multi-stranded. Secondary venation festooned brochidodromous; secondaries thin relative to the primary, densely arranged (5 to 6 pairs per cm at the middle portion of the lamina), opposite to alternate, sometimes decurrent on primary vein, moderate acute, straight or slightly uniformly curved, sinuous near the margin, looping with super-adjacent secondary branch at acute angle; intercostal regions exmedially elongate; two series of excostal secondary loops exmedially elongate, both with rounded outer sides. Intersecondaries common, usually 1 to 2 per intercostal region, interlarding with both secondary and tertiaries, decurrent on the primary and sometimes originating from the exmedial side of secondari es, generally oriented at oblique angles to secondaries and unevenly dividing the intercostal region, intergrading with tertiaries or joining with the superadjacent secondary vein. Tertiaries originating from secondary or intersecondaries, reticulate, more or less sinuous in course; some tertiaries intergrading with quaternary veins. Quaternary venation irregularly curved; intergrading with tertiaries. Marginal venation looped, the loops tending to be flattened parallel to the margin. Number of specimens examined. 6.

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175 Paratypes. UF18267-16562, 16562Â’; 16610, 16610Â’; 24833, 24833Â’; 24835; 26153. Discussion. The specimens from the Courtland I locality show more variation in leaf shape than those from the Rose Creek I locality, Nebraska. Other characters are consistent with those from Rose Creek I locality of Nebraska described by Upchurch and Dilcher (1990). For comparison with other fossils and the affinities with extant angiosperms, please refer to Upchurch and Dilcher (1990). They also compared Densinervum kaulii with extant Magnoliidae but found no close resemblance to any extant family. The implied close relationship between Crassidenticulum decurrens and Densinervum kaulii suggests that Densinervum kaulii has some relationship to modern Chloranthaceae. cf. LAURACEAE Pandemophyllum Upchurch and Dilcher 1990 Pandemophyllum kvacekii Upchurch and Dilcher 1990 (Figure 54, 6-9) Generic and specific diagnosis . See Upchurch and Dilcher (1990). Description. Lamina wide elliptic to narrow elliptic, L/W 1.5 to 3; lamina 2 to 7 cm long by 1.1 to 2.7 cm wide; base acute; demarcation between petiole and blade not well defined, petiole 0.4 to 1.2 cm long by 1.2 mm wide, obviously curved, margin entire, with mechanical reinforcement and occasional insect damage. Primary venation pinnate; primary vein stout, straight. Secondary venation brochidodromous, brochidodromous loops flattened only near the apex; secondaries thin relative to the primary vein, predominately 5 to 6 pairs per leaf, subopposite, predominately moderate (occasionally

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176 narrow) acute; slightly curved to form loops near the margin; intercostal regions exmedially elongate but decreasing in length apically; one series of excostal secondary loops well developed; the lowermost pair of secondaries extending 2/3 of the leaf lamina. Intersecondaries present but often difficult to distinguish from secondaries, branching to form tertiaries. Tertiary venation reticulate to sometimes percurrent; tertiaries moderate relative to secondaries, angle of origin (of those percurrent veins) predominately rightright (RR), primary vein-tertiary angle d ecreasing upward, course irregular, sometimes wavy. Quaternary veins reticulate, course irregular, or wavy. Veins of higher order poorly preserved. Number of specimens examined. 5. Holotype. Pandemophyllum kvacekii Upchurch and Dilcher 1990, pl.12, Figure 8. Paratypes. UF18267-26136; 26138; 16142; 16570II. Discussion. See Upchurch and Dilcher (1990), for comparison with other fossils and modern affinities. Pandemophyllum attenuatum Upchurch and Dilcher 1990 (Figure 53, 4-11) Pandemophyllum attenuatum Upchurch and Dilcher 1990, p.29-30; pl.13, Figures 3-5; pl.16, Figures 1-6; text figure 11. Specific diagnosis (emended). Leaf ovate to lanceolate; apex attenuate to strongly attenuate. Primary venation pinnate; primary vein multistranded. Secondary venation festooned brochidodromous; flattened brochidodromous arches present in the apical half of lamina; intercostal regions exmedially elongate basally, becoming

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177 predominantly isodiametric and with apical attenuation in the apical half of lamina. Tertiary venation predominantly reticulate; tertiaries moderate relative to secondaries. Description. Leaf ovate to lanceolate, L/W 1.5 to 4.8; lamina 2 to 11 cm long by 1.3 to 2.5 cm wide; apex strongly attenuate; base cuneate; margin entire, reinforced; petiole normal, demarcation between petiole and blade indistinct, 1.6 cm long (estimated length) by up to 1.2 mm wide, obviously curved; galls common on some leaf lamina. Primary venation pinnate; primary vein moderate, multistranded. Secondary venation festooned brochidodromous, with flattened br ochidodromous arches in the upper 2/3 of the lamina; secondaries moderate relative to primary vein, 5 to 8 pairs, alternate to subopposite, with somewhat irregular spacing, or iginating at narrow acute angle (<45); secondaries in the lower 2/3 to of lamina curved gradually, joining exmedially branches of superadjacent secondaries to form flattened brochidodromous arches at obtuse angles, while those in the upper 1/3 of lamina joining superadjacent secondaries at almost 180 angles to form flattened brochidodromous arches; intercostal regions in the basal 2/3 of the lamina exmedially elongate, intercostal regions in the upper 1/3 of the lamina apically prolonged; one series of excostal secondary loops well-developed, apically oriented. Intersecondaries present in some intercostal regions in the lower half of lamina, branching to form tertiaries. Tertiary venation predominately reticulate; tertiaries moderate, angle of origin variable, irregularly spaced, course irregular. Veins of higher order and marginal venation poorly preserved. Number of specimen examined . 14. Holotype. Pandemophyllum attenuatum Upchurch and Dilcher 1990, pl.13, Figure 3)

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178 Paratypes. UF1575898a; 4698b; 8305. UF18267-26119; 16570I; 24859Â’; 26120; UF18844-32488; 32487. Discussion. Specimens from the Courtland I locality, Minnesota, show much more variation in the shape of the leaf apex than that from the Rose Creek I locality, Nebraska, and some have well-preserved petioles. The leaf apex can vary from short attenuate to strongly attenuate (Figure 53, 5-6; Figure 53, 11). Pandemophyllum gracifolia Hongshan Wang sp. nov. (Figure 53, 12-14) Specific diagnosis. Leaf elliptic, thin. Margin entire, with structural reinforcement; primary venation pinnate, multistranded, straight. Secondary venation brochidodromous; secondary vein thick relative to primary vein, diverging from primary vein at very narrow acute angles; secondaries gradually curved to join exmedial branches of superadjacent secondary vein at obtuse angles to form flattened arches; secondary arches always enclosed by tertiary and quaternary arches, distinction between intercostal and excostal region not obvious; lower 3 to 4 pairs of secondaries extending a distance of at least half lamina length. Intersecondaries present, only extending a short distance, either truncated by or intergrading with tertiaries in the intercostal region. Intercostal region enclosed by secondaries very long with respect to their length. Tertiaries in the intercostal region thin relative to the secondari es, often occur in the distal half of the intercostal region, percurrent, spacing irregular; tertiaries more or less sinuous in course, angle of origin predominately acute-obtuse. Quaternary veins thin, irregularly reticulate, sometimes intergrading with tertiaries. Tertiary and quaternary arches in the excostal region tend to be flattened with their long axes parallel to the margin.

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179 Description. Leaf elliptic, thin; leaf lamina 2.5 to 4 cm long by 1.1 to 1.4 cm wide (L/W 2 to 3). Margin entire, with structural reinforcement; primary venation pinnate, multistranded, straight. Secondary venation brochidodromous; secondary vein thick relative to primary vein, 5 to 6 pairs per lamina, alternate or occasionally subopposite, diverging from primary vein at very narrow acute angles (<30 ); secondaries gradually curved to join exmedial branches of superadjacent secondary vein at obtuse angles to form flattened arches; secondary arches always enclosed by tertiary and quaternary arches, distinction between intercostals and excostal region not obvious; lower 3 to 4 pairs of secondaries extending a distance of at least half lamina length; cross veins between secondaries near margin thin, resulting an eucamptodromous secondary venation pattern. Intersecondaries present, but only extending a short distance (less than half distance of the intercostal region), either truncated by or intergrading with tertiaries in the intercostal region. Intercostal region enclosed by secondaries very long with respect to their width (distance measured between and perpendicular to two adjacent secondaries). Tertiaries in the intercostal region thin relative to the secondaries, often occur in the distal half of the intercostal region, percurrent, spacing irregular; tertiaries more or less sinuous in course, angle of orig in predominately acute-obtuse. Quaternary veins thin, irregularly reticulate, sometimes intergrading with tertiaries. Tertiary and quaternary arches in the excostal region tend to be flattened with their long axes parallel to the margin. Veins of higher order not observed. Number of specimens examined. 3. Holotype. UF18267-26122. Paratypes. UF18267-16611; 26121.

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180 Derivation of epithet. Latin, “graci-“ means “slender” and “folia” means “leaves,” referring to the slender nature of the leaf. Discussion. The elliptic leaf shape, entire margin with structural reinforcement, multistranded primary vein, brochidodromous secondary venation appearing to be eucamptodromous because of thin cross veins, lower 3 to 4 pairs of secondaries extending a distance of at least half lamina length, presence of intersecondaries, and intergrading of tertiary and higher order veins all indicate a possibly close relationship of Pandemophyllum gracifolia with the Lauraceae. For example, Pandemophyllum gracifolia is similar to Neolitsea cambodiana Lec. Var. g labra Allen. in lower order venation pattern but they differ in that the latter has more obtuse diverging angle of secondaries from primary vein, rare and simple intersecondaries, well differentiated tertiary vein which are percurrent, thick and orthogonal quaternary veins anastomosing with quinternary veins to form well developed areoles (Yu and Chen, 1990). It is similar to Cinnamomum obliqicarpon (Klucking, 1987) in leaf shape and secondary venation patterns but they differ in that the latter has more secondaries, percurrent tertiaries. In all , the suite of characters of Pandemophyllum gracifolia separates this species from all extant species and other fossil species of Pandemophyllum . SAXIFRAGALES cf. CERCIDIPHYLLACEAE Trochodendroides Berry 1922 Trochodendroides rhomboideus (Lesquereux) Berry 1922 (Figure 51, 1-7; Figure 51, 10)

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181 Ficus? rhomboideus Lesquereux, American Journal of Science, 2nd ser., vol. 46, p. 96, 1868. Phyllites rhomboideus Lesquereux, Lesquereux, 1874, U.S. Geological Survey Report 6, p. 112, pl. 6, Figure 8. Ficus ? rhomboideus Lesquereux, Lesquereux, 1878, Am. Journ. Sci., vol. 36, p. 96; Ills. Cret. and Tert. Fl. (1878), pl. 3, Figures 1, 2. “Populus” elliptica Newberry, Newberry, 1898, U.S. Geological Survey Monograph 35, p. 43, pl. 3, Figures 1, 2. Specific diagnosis. Leaf simple, wide ovate to very wide ovate (rhomboidal), apex acute; base obtuse, decurrent; distal half of the margin toothed, serration type convex-convex (A-1), serrate axes inclined to the tangent of the margin, apical angle of serrate teeth obtuse (>90º), sinus rounded, teeth chloranthoid type, almost all of the same size, spacing regular. Glands may be obvious at tooth apex and leaf apex; petiole normal, base inflated, three stranded. Primary venation perfectly basal acrodromous; medial primary vein moderate, multi-stranded; no veins of secondary order originating form medial primary vein; two lateral primary veins originating from petiole, giving rise to exmedial branches very close to the base; medial primary vein straight, almost the same thickness as that of lateral primary veins, extending directly to leaf apex. Exmedial branches from lateral primary veins originati ng at narrow acute angles, abruptly curved to join super-adjacent branches at right or obtuse angles to form loops, which in turn enclosed by higher order arches; tertiaries random reticulate, course irregular; quaternary veins relatively randomly oriented, course irregular. Areoles imperfect, small (<0.3 mm),

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182 randomly arranged, dominantly quadrangular and pentagonal; veinlets branching once and ending freely to form open venation; marginal veinlets incomplete, ending freely. Description. Leaf simple, symmetric to slightly asymmetric, wide ovate to very wide ovate (rhomboidal), L/W approximately 1 to 1.2 (two immature leaves ovate, see Figure 51, 1); leaf size variable, from 2.6 to 6 cm long (estimated length) by 2.6 to 5 cm wide; apex acute; base obtuse, decurrent; distal half of the margin toothed, serration type convex-convex (A-1), apical side shorter than basal side; serrate axes inclined to the tangent of the margin, apical angle of serra te teeth obtuse (>90º), sinus rounded, teeth of chloranthoid type, glandular with a clear, non-deciduous (i.e., papillate) swollen cap, shape variable, acuminate-convex is common, acuminate-acuminate and concaveacuminate also occur. Venation with a medial secondary or tertiary vein accompanied by two prominent, converging, higher order lateral veins, which also enter the tooth apex or fuse with the medial vein below the apex. Occasionally, as in Ascarina , one of the converging laterals is suppressed (Hickey and Wolfe, 1975);” teeth almost all of one size, spacing regular and dense on distal half of l eaf lamina. Glands may be obvious at tooth apex and leaf apex; petiole normal, up to at least 2.6 cm long by 1 mm wide, base slightly inflated (Figure 51, 2), three stranded (Fi gure 51, 10), tending easily to be broken from lamina. Primary venation perfectly basal acrodromous, two or more primary or strongly developed secondaries running in convergent arches toward the leaf apex, arches not recurved at base; medial primary vein moderate, multi-stranded; lateral primary veins originating from petiole (Figure 51, 1; Figure 51, 7); medial primary vein straight, almost the same thickness as that of lateral primary veins, extending directly to the acute apex; no veins of secondary order originating from medial primary vein; one exmedial branch

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183 arising from each lateral primary vein very close to the base, extending about 1/2 to 2/3 distance to apex. Exmedial branches from these veins originating at narrow acute angles, abruptly curved to join super-adjacent branches at right or obtuse angles to form loops, which are enclosed by higher order arches; tertiaries random reticulate, course irregular; quaternary veins relatively randomly oriented, course irregular. Areoles imperfect, small (<0.3 mm), randomly arranged, dominantly quadrangular and pentagonal; veinlets branching once and ending freely; marginal veinlets incomplete, ending freely. Number specimens examined. 12. Holotype. Trochodendroides rhomboideus Lesquereux, Lesquereux, 1874, U.S. Geological Survey Report 6, p. 112, pl. 6, Figure 8. Paratypes. UF18267-16596, 16596’; 16592b; 16595, 16595’; 16602, 16602’; 16607; 21217. Discussion. Phyllites is a genus established by Brongniart (1822) for dicoteledonous leaves from he Miocene of Oenignen, Switzerland. This genus is based on the type species Phyllites populina Brongniart (Brongniart, 1822). However, a miscellaneous assemblage of leaves of doubtful affinity were included in the genus, and the type species has little significance. Berry (1922a) proposed the genus Trochodendroides for fossil leaves that “appear to be referable to the family Trochodendraceae (Berry, 1922a, p. 166).” He designated Phyllites rhomboideus Lesquereux (Lesquereux, 1874) as the type species for this genus. Among angiosperm leaf fossils from the Dakota Formation, “Paliurus” cretaceus Lesquereux (Lesquereux, 1892) resembles Trochodendroides rhomboideus in overall leaf shape, acrodromous primary venation, basilar lateral primary veins, “triplenerved”

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184 appearance, and toothed lamina on distal ha lf, but it differs from it in the following: lateral primary veins straight and not converging toward leaf apex, medial primary vein thicker than lateral primary veins, and several veins of secondary order originating form the medial primary vein on the distal portion. Further comparison is difficult because of the lacking of fine venation characters of “Paliurus” cretaceous. Trochodendroides rhomboideus resembles “Populus” flabellum Newberry (Newberry, 1898) in gross shape and acrodromous primary venation, but it differs from it in having exmedial branches from primary veins forming loops instead of forking. Trochodendroides rhomboideus is similar to Trochodendron nastae Pigg, Wehr, and Ickert-Bond (Pigg et al. 2001) from the Eocene Republic flora of northeastern Washington in gross leaf shape, and primary venation composed of a medial and two lateral primary veins, but it differs from it in that Trochodendroides rhomboideus has perfectly basal acrodromous primary venation, two or more primary or strongly developed secondaries running in convergent arches toward the leaf apex. Leaf architecture (acrodromous venation a ssociated with chloranthoid teeth) of Trochodendroides rhomboideus indicates its close relationship with Trochodendraceae. However, only isolated leaves are observed from the Courtland I locality and this makes it difficult to assign Trochodendroides rhomboideus to any extant families. MAGNOLIALES Liriophyllum (Lesquereux) Dilcher and Crane 1984 Liriophyllum siemia Hongshan Wang sp. nov. (Figure 50, 11; Figure 58, 1-2; Figure 58, 6-7, Figure 58, 10-11)

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185 Specific diagnosis. Leaf very wide ovate, always with emarginate apex at variable depth; base truncate or truncate in overall but obtuse cuneate near petiole; petiole normal, base inflated; margin entire. Primary venation pinnate; primary vein moderate, multistranded, straight in course. S econdary venation festooned brochidodromous; secondaries thin relative to primary vein, diverging from primary vein at uniform, moderate acute angles; secondary vein joining exmedial branches of superadjacent secondary vein or superadjacent secondaries to form secondary arches, these enclosed by secondary and tertiary arches; intersecondary vein present, extending half distance to the margin before branching to form tertiaries. Extreme base of lamina with 2 basal veins of secondary or intersecondary/tertiary order, those of secondary order always with distinct exmedial branches. Tertiary vein thin relative to secondary veins, random reticulate. Description. Leaf symmetrical, very wide ovate, L/W less than 1, lamina 4.1 to 5 cm long by 4.5 to 5 cm wide, always with emarginate apex at variable depth (up to ¼ depth of leaf lamina); base truncate or truncate in overall but obtuse cuneate near petiole; petiole normal, 1.6 cm long by 0.5 cm wide, base inflated; margin entire. Primary venation pinnate; primary vein moderate, multistranded, straight in course. Secondary venation festooned brochidodromous; secondaries thin relative to primary vein, 5 pairs per leaf, diverging from primary vein at uniform, moderate acute angles; secondary vein joining exmedial branches of superadjacent secondary vein or superadjacent secondaries to form secondary arches, these enclosed by secondary and secondary arches; intersecondary vein present, parallel to secondary vein, extending half distance to the margin before branching to form tertiaries. Extreme base of lamina with 2 basal veins of

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186 secondary or intersecondary/tertiary order, those of secondary order always with distinct exmedial branches. Tertiary veins thin relative to secondary veins, random reticulate. Number of specimens examined. 6. Holotype. UF18267-26156. Paratype. UF18267-26152; 26118, 26118’; 26121, 26121’. Derivation of epithet. In honor of G. Siem and in recognition of his contributions to the collections of the Courtland I locality, Minnesota. Discussion. Dilcher and Crane (1984a) emended the diagnosis of the genus Liriophyllum as following: “Leaf petiolate, bilobed, deeply divided for at least half its length. Midrib stout, extending to the base of the sinus and forking into two prominent veins, distinct from the secondaries below, which form the leaf margin typically from about 0.3 to 0.16 of the lobe length. Above this point the lamina arches away from the vein into the sinus and broadens distally to form each lobe.” The characters of Liriophyllum siemia from Courtland I locality, Minnesota, are consistent with the generic diagnosis except that the leaf is divided less than half of its length. It is possible that Liriophyllum siemia represents a transitional leaf type between species with unindented apex to species with deeply indented apex. PROTEALES PLATANACEAE Credneria Zenker 1883 Credneria cyclophylla (Heer) Hongshan Wang comb. nov. (Figure 55, 1-7)

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187 “Populus” cyclophylla Heer, Lesquereux, 1858, Proc. Acad. Nat. Sci., Philadelphia, vol. 10, 266 pp. “ Populus” litigiosa Heer, 1866, Nouv. Mem. Soc. Helv. Sci. Nat., vol.12, p.13, pl.1, Figure 2. “ Populus” lancastriensis Lesquereux, 1868, America Journal of Science and Arts. Loc. Cit., p.93. “Populus” (?) cordifolia Heer, 1868, Ann. N.Y. Lyc. Nat. Hist., vol.9, p. 18. “ Populus” lancastriensis , Lesquereux 1874, The Cretaceous Flora, United States Geological Survey of the Territories, Part 1. p.58, pl. 3, Figure 1. “ Populus” cyclophylla , Lesquereux 1874, The Cretaceous Flora, United States Geological Survey of the Territories , Part 1. p.59-60, pl. 4, Figure 5; pl.24, Figure 4. “Populus” litigiosa Heer, 1878, Ills. Cret. And Tert. FL., pl.3, Figure6. “Populus” (?) cordifolia Heer 1878, Ills. Cret. And Tert., p.5, Figure 5. Populites litigiosus (Heer) Lesquereux, 1892, p.46, pl. 7, Figure7; pl. 8, Figure5; pl. 46, Figure6; pl. 47, Figure1. “Populus” (?) cordifolia Heer, 1898, Later Extinct Floras of North America, United States Geological Survey, p. 40, pl. 3, Figure 7; pl.5, Figure 5. “ Populus” cyclophylla Heer, Newberry, 1898, Later Extinct Floras of North America, United States Geological Survey, p. 41, pl. 3, Figure 3, 4; pl. 4, Figure1. “Populus” litigiosa Heer, 1898, Later Extinct Floras of North America, United States Geological Survey, p. 45, pl. 3, Figure 6.

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188 Specific diagnosis. Leaf petiole inflated at base. Primary venation pinnate; primary vein weak straight, multistranded. Secondary venation simple craspedodromous, with all of the secondaries and their branches terminating at the margin, giving rise to glandular projections; secondaries thick relative to primary vein; two prominent basal secondaries depart from primary vein at extreme base of lamina; secondaries arising from primary vein at moderate acute angles, opposite to subopposite, decurrent; secondaries predominately straight in course, with occasional exmedial secondary branches except the lowest pair; generally 4 to 5 exmedial branches from secondaries of the lowest pair, slightly recurred before terminating at the margin. Tertiaries moderate relative to secondary vein, percurrent, course convex; angl e of origin right-acute (RA) or right-right (RR), course convex; primary veintertiary angle oblique, decreasing upward, those of the same intercostal region almost with constant angle; arrangement predominately alternate. Quaternary veins thin, transverse, predominately orthogonal, arrangement predominately opposite; quinternary veins moderate relative to quaternary veins, orthogonal; areoles formed by quinternary veins well developed, randomly arranged, pentagonal in shape, small in size (0.3 to 1 mm). Description. Leaf symmetrical; orbiculate or wide ovate to very wide ovate, L/W 1 to 1.1, lamina 6 to 12 cm long by 6 to 12 cm wide (estimated minimum and maximum length); apex rounded, emarginate or mucronate; base predominately cordate in overall shape but decurrent on the petiole, occasionally cuneate; margin entire, slightly wavy; petiole inflated (Figure 55, 2 as indicated by arrow) at base, 1.1 to 4.5 cm long by 0.6 to 0.8 mm wide. Primary venation pinnate; primary vein weak (less than 1.25%), straight, multistranded. Secondary venation simple craspedodromous, with all of the secondaries

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189 and their branches terminating at the margin, giving rise to glandular projections; secondaries thick relative to primary vein, multistranded on some specimen; two prominent basal secondaries depart from primary vein at extreme base of lamina; predominately 5 to 6 pairs in a leaf; secondaries arising from primary vein at moderate acute angles (predominately 45º, but occasionally maybe less), angle of divergence almost uniform (at an angle of 45 ), opposite to subopposite, decurrent; secondaries predominately straight in course, with occasional exmedial secondary branches except the lowest pair; generally 4 to 5 exmedial branches from secondaries of the lowest pair, slightly recurred before terminating at the margin; the lowest pair arising from primary vein at 5 mm distance above base; 4 to 5 tertiary branches originating from the lowest branch apically curved near the margin before terminating at the margin; no intersecondary vein. Tertiaries moderate relative to secondary vein, percurrent, course convex; angle of origin right-acute (RA) or right-right (RR), course convex; primary veintertiary angle oblique, decreasing upward, those of the same intercostal region almost with constant angle; arrangement predominately alternate, close (internal between veins less than 0.5 cm on small leaves or distant (interval between veins greater than 0.5 cm on large leaves). Quaternary veins thin, transverse, predominately orthogonal, arrangement predominately opposite; quinternary veins moderate relative to quaternary veins, orthogonal; areoles formed by quinternary veins well developed, randomly arranged, pentagonal in shape, small in size (0.3 to 1 mm). Number of specimens examined. 36. Holotype. 1858 Credneria cyclophylla Heer, Proc. Phila. Acad. Nat. Sci., p. 266.

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190 Paratypes. UF18267-16601, 16601Â’; 26128, 26128Â’; 26134; 16597, 16597Â’; 26154; 24819, 24819Â’. Discussion. The genus Credneria was established by Zenker (1833) and emended by Schwarzwalder (1986) to represent fossil leaves with unlobed or slightly three-lobed lamina. The following features: simple unlobed leaf with inflated petiole base, pinnate primary venation, craspedodromous secondary venation, and percurrent tertiaries are consistent with the generic diagnosis. As discussed by Schwarzwalder and Dilcher (1981) and Schwarzwalder (1986, 1991), Credneria cyclophylla is placed in the Platanaceae. Clade UNKNOWN Dicotylophyllum crasseprimus sp.nov. (Figure 59, 6-7) Specific diagnosis. Leaf margin entire. Primary venation pinnate; primary vein massive, multistranded. Secondary vein forming an intramarginal vein very close to the margin; secondary thin, numerous, decurrent on primary vein, angle of divergence moderate acute, course irregular, terminating on intramarginal vein. Description. Leaf tending to break apart. Observed leaf lamina 15 cm long by 6 cm wide. Margin entire. Primary venation pinnate; primary vein massive, 4 mm wide, multistranded. Secondary vein forming an intramarginal vein very close to the margin; secondary thin, numerous, decurrent on primary vein, angle of divergence moderate acute, course irregular, terminating on intramarginal vein. Veins of higher order not observed. Number of specimens examined. 1.

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191 Holotype. UF18267-16604. Derivation of Epithet. Latin, “crassus” means “thi ck, stout” and “primus” means “first, chief,” referring to the thick primary vein of the species. Discussion. Though only one specimen is available for examination, Dicotylophyllum crasseprimus is easily to be distinguished from all other species of angiosperm leaves from the Dakota Formation by its large leaf, massive multistranded primary vein, thin secondary vein, and its intramarginal vein. These characters may indicate some relationship within the Magnoliidae. Dicotylophyllum crasseprimus is similar to Ficus elastica Roxb (Yu and Chen, 1990) in having massive primary vein, numerous secondary veins, and intramarginal veins, but they differ in that the latter has secondary veins more closely arranged, long elliptic or oblong leaf shape, and common intersecondary veins. Dicotylophyllum carlsonia Hongshan Wang sp. nov. (Figure 52, 3) Specific diagnosis. Leaf narrow elliptic; apex acuminate, base decurrent; petiole region with decurrent wing of lamina tissue; distal 1/3 portion of leaf margin toothed, proximal portion entire; tooth typically stra ight-straight (B-2) or occasionally convexstraight (B-1), regularly spaced, sinus smooth. Primary venation pinnate; primary vein stout, slightly curved, multistranded. Secondary venation brochidodromous; secondaries thin relative to primary vein; secondaries alternate, strongly decurrent on the primary veins; secondaries originating from primary vein at moderate acute angles, uniformly curved, joining exmedial branches of superadjacent secondary vein at right angles, forming one series of secondary arches in th e excostal region; glandular teeth with their

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192 axes strongly inclined to the tangent of the margin; serrations regular in space, apical angle acute. Intersecondaries present. Description. Leaf tending to break apart, narrow elliptic, L/W 3; leaf lamina 11.5 cm long by 3.8 cm wide; apex acuminate, base decurrent; petiole region with decurrent wing of lamina tissue; distal 1/3 portion of leaf margin toothed, proximal portion entire; tooth typically straight-straight (B-2) or o ccasionally convex-straight (B-1), regularly spaced, sinus smooth. Primary venation pinnate; primary vein stout, slightly curved, multistranded. Secondary venation brochidodromous; secondaries thin relative to primary vein, 12 pairs of secondaries regularly spaced with 0.6 to 0.7 cm distance of two adjacent veins (measured at half distance to the margin); secondaries alternate, strongly decurrent on the primary veins; secondaries originating from primary vein at moderate acute angles (45 to 65 ), uniformly curved, joining exmedial branches of superadjacent secondary vein at right angles, forming one series of secondary arches in the excostal region; 8 to 13 glandular teeth on 1/3 distal por tion of the lamina, with their axes strongly inclined to the tangent of the margin (with angle between serrate axes and tangent of the margins lee than 10 degrees); serrations regular in space, apical angle acute. Intersecondaries present, extending no more than 1/2 distance from primary vein to leaf margin. Veins of higher order poorly preserved. Number of specimens examined. 1. Holotype. UF18267-16603, 16603Â’. Derivation of epithet. In honor of B. Carlson and in recognition of his contributions to the collection of specimens from Courtland I locality, Minnesota.

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193 Discussion. Only secondary order venation was observed, however, this species possesses a suite of distinctive characters such as narrow elliptic leaf shape, acuminate apex, petiole with decurrent wing of lamina tissue, distal 1/3 portion of leaf margin toothed, multistranded primary venation, and brochidodromous secondary venation. Dicotylophyllum tulipifera (Heer) Hongshan Wang comb. nov. (Figure 54, 10-12) “Liriodendron” tulipifera Heer, 1882, pl. 23, Figures 1-2. “Liriodendron” tulipifera Heer, Lesquereux, 1892, pl.29, Figure 4 (no description). Specific diagnosis. Leaf small. Base obtuse, decurrent. Margin entire. Petiole normal. Primary venation pinnate; primary vein thin. Secondary venation brochidodromous; secondary veins thin, course irregular; spacing irregular on primary vein. Tertiary veins thin, reticulate, course irregular. Quaternary veins thin, reticulate, forming very small but well developed areoles. Veinlets none. Description. Leaf small. Lamina form possibly wide ovate, L/W 1.3, lamina 2 cm long (estimated length) by 1.6 cm wide. Apex missing. Base obtuse, decurrent. Observed margin entire. Petiole normal, 5 mm long by 1mm wide. Primary venation pinnate; primary vein thin. Secondary venation brochidodromous; secondary veins thin, 5 pairs per lamina; course irregular; spacing irregular on primary vein. Tertiary veins thin, reticulate, course irregular, originated fr om primary or secondary veins. Quaternary veins thin, reticulate, forming very small but well developed areoles. Veinlets none. Number of species examined . 1. Holotype. Dicotylophyllum tulipifera Heer (Heer, 1882), Paratype. UF15706-16588, 16588’.

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194 Discussion. Both Heer (1882) and Lesquereux (1892) assigned similar specimens to extant genus Liriodendron . However, these fossil leaves donÂ’t possess features circumscribe the modern leaves, such as saddle-shaped leaf, presence of intersecondary veins, and craspedodromous secondary venation. Crepetia Hongshan Wang gen. nov. Generic diagnosis. Leaf very wide ovate. Margin slightly wavy with structural enforcement, glandular teeth generally with three veins terminate at the base of the marginal glands. Primary venation actinodromous. One lateral primary vein on each side of the medial primary vein with almost the same thickness, bifurcating once immediately after diverging point; exmedial branches from lateral primary veins bifurcating once near the leaf margin to join the superadjacent exmedial branch forming an arch to enclose intercostal region. Tertiaries originating from those arch (excostal region) extending directly to the base of marginal glands or joining others very close to the margin to form fimbrial veins; Intercostal tertiaries thin, originating from either lateral primary veins or exmedial branches of lateral primary veins, reticulate. Quaternary veins thin, reticulate, and irregular in course, originating from tertiaries at predominately right angles. Derivation of generic name. In honor of William L. Cr epet and in recognition of his contributions to paleobotany. Crepetia minudentis Hongshan Wang sp. nov. (Figure 56, 1-7) Specific diagnosis. Same as for genus.

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195 Description. Leaf very wide ovate, (L./W <1); lamina 6.5 to 9.4 cm long by 7 to 11 cm wide (estimated width); base truncate or cordate with a cuneate extension of leaf lamina at the petiole; petiole up to 2.3 cm long by 1 mm wide; margin slightly wavy with structural enforcement (wave length 6 to 11 mm and height up to 1 mm), glandular teeth (1 to 4 per cm) up to 0.5 mm high by 0.5 mm wide, generally three veins terminate at the base of the marginal glands. Primary venation actinodromous, lateral primary veins extending more than 2/3 of leaf lamina before branching into finer veins. One lateral primary veins on each side of the middle primar y vein, these almost the same thickness as middle primary veins, bifurcating once immediat ely after origination; exmedial branches from lateral primary veins bifurcating once near the leaf margin to join the superadjacent exmedial branch forming an arch to enclose in tercostal region; Tertiaries originating from those arch (excostal region) extending directly to the base of marginal glands or joining others very closely to the margin to form fimbrial veins; Intercostal tertiaries thin, originating from either lateral primary veins or exmedial branches of lateral primary veins, reticulate. Quaternary veins thin, reticulate, and irregular in course, originating from tertiaries at predominately right a ngles. Veins of higher order not observed. Number of specimens examined. 2. Holotype. UF18267-26150, 26150’ Paratypes. UF18267-16590, 16590’. Derivation of epithet. Latin, “minutus” means “little, small,” and “dentis” means “tooth,” referring to the tiny teeth on leaf margin. Discussion. The new genus is set up to represent the Dakota Formation fossil angiosperm leaves with the following combined features: very wide ovate shape ; margin

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196 slightly wavy with structural enforcement, small glandular teeth generally with three veins terminate at the base of the marginal glands; primary venation actinodromous. The suite of characters of Crepetia minudentis is unique and the species is easily distinguished from all other Dakota Formation angiosperm fossil species. Glandilunatus Hongshan Wang gen. nov. Generic diagnosis. Leaf palmately lobed, apex of lobes obtuse; conspicuous cresulent glands on the lobes; petiole normal. Primary venation paliactinodromous. Secondaries originating from primary vein at uniform (narrow acute) angles. Both exmedial and admedial branches from basal secondaries extending directly to major tooth apex, while these may giving rise to fine veins on both exmedial and admedial sides, but the finer veins terminate on the marginal gland base on secondary teeth on the sinuous. Tertiaries thin, angle of origin acute-acute (AA), course convex, originating at narrow acute angles on the exmedial side of the secondaries, extending into glands on the margin or the sinuous. Derivation of generic name. Latin, “glandis” means “gland” and “lunatus” means “shaped like a crescent moon,” referring to the cresulent glands on leaf margin. Glandilunatus minnesotense Hongshan Wang sp. nov. (Figure 54, 1-5) Specific diagnosis. Leaf palmately lobed, with 3 shallow lobes and the margins of each lobe repeatedly lobed; apex of lobes obtuse; conspicuous cresulent glands terminate the lobes; base semi-cordate; petiole normal. Primary venation palinactinodromous; medial primary vein massive to stout. Two major basal secondaries sub-opposite. Secondaries originating from primary vein at uniform (narrow acute)

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197 angles. Both exmedial and admedial branches from basal secondaries extending directly to major tooth apex, while these may giving rise to fine veins on both exmedial and admedial sides, but the finer veins terminate on the marginal gland base on secondary teeth on the sinuous. Tertiaries thin, angle of origin acute-acute (AA), course convex, originating at narrow acute angles on the exmedial side of the secondaries, extending into glands on the margin or the sinuous. Description. Leaf palmately lobed, estimated over 5 cm long by 5.5 to 7.5 cm wide, with 3 shallow lobes and the margins of each lobe repeatedly lobed; apex of lobes obtuse; conspicuous cresulent glands terminate the lobes; base semi-cordate; petiole normal, at least 3.5 cm long by about 2 mm wide. Primary venation palinactinodromous; medial primary vein massive to stout. Two major basal secondaries sub-opposite. Secondaries originating from primary vein at uniform (narrow acute) angles. Both exmedial and admedial branches from basal secondaries extending directly to major tooth apex, while these may giving rise to fine veins on both exmedial and admedial sides, but the finer veins terminate on the marginal gland base on secondary teeth on the sinuous. Tertiaries thin, angle of origin acute-acute (AA), course convex, originating at narrow acute angles from the exmedial sides of the secondaries, extending into glands on the margin or terminating on the sinuous. Veins of higher order poorly preserved. Number of specimens examined. 8. Holotype. UF18267-16585. Paratypes. UF18267-24841; 24771; 26151. Derivation of epithet. Referring to the occurrence of this species in Minnesota.

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198 Discussion. The new genus Glandilunatus is established to represent those Dakota Formation Angiosperm leaves with palmately lobed leaf shape, cresulent glands on leaf margin, paliactinodromous primary venation, all secondaries and their higher order branches extending directly to tooth apices. Glandilunatus minnesotense is similar to “Cissites” ingens Lesquereux (Lesquereux, 1892) in leaf shape, and primary and secondary venation patterns, but it differs from it in having strong primary and secondary veins, conspicuous cresulent glands on apexes of lobes, and all primary, secondary and their branches, and tertiary veins all terminating on the teeth. Glandilunatus minnesotense is similar in leaf shape to some extant member of Populus but it differs from them in that it does not possess the typical salicoid type tooth. In addition, most species of Populus have pinnate, rather than palinactinodromous venation. Dicotylophyllum coughlantia Hongshan Wang sp. nov. (Figure 57, 1-8) Specific diagnosis. Leaf very widely ovate, base obtuse cuneate or cordate in overall shape, cuneate at the petiole attachment; margin with broad teeth, teeth smoothly rounded, without pointed apex; crenations no more than 1cm; teeth irregularly spaced with rounded sinuses; petiole normal. Primary venation pinnate; primary vein moderate in thickness, straight in course. Secondary venation craspedodromous; secondaries thick relative to primary veins, subopposite, decurrent; angle of divergence uniform; secondaries straight in course, with rare branches extending directly to the apex of the tooth; basal secondaries may branch once, one branch joining superadjacent exmedial branch of secondary vein to form arch while the exmedial branch terminating at the apex of a tooth. Intersecondaries, when present, tend to intergrade with tertiaries, which are

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199 originated from primary vein at more obtuse angles than adjacent secondaries. Tertiary venation thin relative to secondaries; percurrent, course convex; angle of origin predominately acute-acute (AA); primary-tertiary vein angle oblique and decreasing upward; arrangement alternate on secondaries, irregularly closely spaced; some tertiaries intergrading with quaternary veins. Quaternary veins thin, relatively randomly oriented, some intergrading with tertiary or other quaternary veins. Quinternary veins thin, also randomly arranged, sinuous in course, anatomizing to form irregular and small areoles. Areoles imperfect, veinlets curved, simple, no freely ending veinlets. Two series of loops near the margin, the long axes of the loops perpendicular to the margin, with the ultimate veins originating from outer loops. Marginal ultimate veins incomplete, freely ending veinlets terminating on the margin. Description. Leaf very widely ovate, L/W approximately 1; lamina 8 cm long by 8 cm wide (estimated maximum length); apex missing; base obtuse cuneate or cordate in overall shape, cuneate at the petiole attachment; margin with broad teeth, teeth smoothly rounded, without pointed apex; crenations no more than 1 cm high (measured by the direction perpendicular to the tangent of two adjacent sinuses); tooth apex inclined to the tangent of the margin at acute angles, basal side more or less smooth and longer than the convex apical side; teeth irregularly spaced with rounded sinuses; petiole normal, at least 1.9 cm long by 2 mm wide. Primary venation pinnate; primary vein moderate in thickness, straight in course. Secondary venation craspedodromous; secondaries thick relative to primary veins, subopposite, decurrent; 4 to 5 pairs of secondaries diverging from primary vein at moderate acute angles (45 to 65 ); angle of divergence uniform; secondaries straight in course, with rare branches, extending directly to the apex of the

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200 teeth; basal secondaries may branch once, one branch joining superadjacent exmedial branch of secondary vein to form arch while the exmedial branch terminating at the apex of a tooth. Intersecondaries, when present, tend to intergrade with tertiaries, which are originated from primary vein at more obtuse angles than adjacent secondaries. Tertiary venation thin relative to secondaries; percurrent, course convex; angle of origin predominately acute-acute (AA); primary vein-tertiary vein angle oblique and decreasing upward; arrangement alternate on secondaries, irregularly closely spaced (interval between veins less than 5 mm); some tertiaries intergrading with quaternary veins. Quaternary veins thin, relatively randomly oriented, some intergrading with tertiary or other quaternary veins. Quaternary veins th in, also randomly arranged, sinuous in course, anatomizing to form irregular and small (less than 0.3 mm) areoles. Areoles imperfect, veinlets cured, simple, no freely ending veinlets observed in areoles. Two series of loops near the margin, the long axes of the loops perpendicular to the margin, with the ultimate veins originating from outer loops. Marginal ultimate veins incomplete, freely ending veinlets terminating on the margin. Number of specimens examined. 2. Holotype. UF18267-20249, 20249Â’. Paratypes. UF18267-24773, 24773Â’. Derivation of epithet. In honor of D. Coughlant and in recognition of his contributions to the collection of Dakota Formation specimens. Discussion. Dicotylophyllum coughlantia differs from platanoid type of leaves in having broad, smoothly rounded teeth on leaf margin, presence of Intersecondary veins which may intergrade with tertiaries, percurrent tertiary veins convex in course, thin

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201 quaternary veins relatively randomly oriented, and quinternary veins also randomly arranged and anatomizing to form irregular and small areoles, and the two series of loops near the margin with the long axes of the loops perpendicular to the margin. Dicotylophyllum leptovena Hongshan Wang sp. nov. (Figure 51, 8-9; Figure 51, 14) Specific diagnosis. Leaf margin entire; petiole normal. Primary venation pinnate; primary vein straight, massive. Secondaries thin relative to primary vein, numerous, slightly curved; angle of divergence wide acute; exmedial branches of secondaries joining intersecondaries and then terminating at the margin or occasionally branching once more, these veins tending to be perpendicular to primary vein and leaf margin; intersecondaries simple, straight or slightly curved, developed less than 1/2 distance from primary vein to leaf margin. Thin intersecondaries also originate from primary at wide acute angles and parallel to secondary and other intersecondaries, developed less than 1/4 distance from primary vein to leaf margin. Marginal ultimate veins hair-like, perpendicular to the margin. Description. Only basal part observed; base slightly obtuse, normal; margin entire; petiole normal, up to 2 mm wide. Primary venation pinnate; primary vein straight, massive, up to 1 mm wide at the middle and 1.5 mm near the base. Secondaries thin relative to primary vein, 3 to 4 pairs per cm, slightly curved; angle of divergence wide acute; exmedial branches of secondaries joining intersecondaries and then terminating at the margin or with occasionally branching once more, these veins tending to be perpendicular to primary vein and leaf margin; intersecondaries simple, 1 or more between secondaries, straight or slightly curved, developed less than 1/2 distance from

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202 primary vein to leaf margin. Thin intersecondaries also originate from primary at wide acute angles and are parallel to secondary and other intersecondaries, developed less than 1/4 distance from primary vein to leaf margin. Marginal ultimate veins hairlike, perpendicular to leaf margin. Number of specimens examined. 1. Holotype. UF18267-21214, 21214’. Derivation of epithet. Greek, “lepto” means “thin or delicate” and Latin, “vena” means “vein,” referring to the thin and delicate secondary and higher order veins. Discussion. Dicotylophyllum leptovena is distinguished from all other angiosperm leaf megafossils from the Dakota Formation by its relatively massive primary vein and thin higher order veins which all tend to be arranged perpendicular to leaf margin. Diversity Analysis Introduction In paleoecology and paleobiogeography, the study of species diversity, especially species richness, is an important component because it forms the basis of such ecological models and hypotheses as mass extinction (Raup, 1972; Raup et al., 1973; Raup, 1975), explanation of latitudinal diversity gradients (Pianka, 1966; Stevens, 1989), and species turnover for terrestrial plants during the ear th’s history (Lidgard and Crane, 1988, 1990; Tiffney and Niklas, 1990). Species diversity is hard to define because it consists of two components, the variety and the relative abundance of species (Magurran, 1988). There are numerous methods to measure species diversity. Magurran (1988) divided species diversity measures into three main categories: species richness indices, species abundance models, and indices based on the proportional abundance of species.

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203 In the second category, many species abundance models have been proposed to interpret the different species abundance patterns but often the biological assumptions on which these are based are discredited or unproven (Magurran, 1988). Indices based on the proportional abundance of species need to take both species evenness and richness into account and thus is very difficult to a pply to paleo-communities because it is difficult to get information on species evenness, which is in turn based on the number of individuals in a community. For example, diffe rent organs (i.e., leaves, flowers, fruits, seeds, stems, etc) of plants, especially those deciduous woody angiosperms, are always shed during their life cycle either through physiological or traumatic mechanisms at different stages of development, hence, they are dispersed and transported to a variety of environments before they are preserved as fossils. When a number of fossil angiosperm leaf specimens are collected from a locality, it is difficult to tell if these specimens of one leaf type represent different individuals. It is more reliable to assume these specimens represented one single taxon (Wang et al., 2000). More specimens of a single taxon, to some extent, do represent the presence of more individuals. On the other hand, species richness indices, is simple and much easier to understand and apply than species abundance models and indices based on the proportional abundance of species. It is measured by the direct count of species (Peet, 1974). For diversity analysis of the Dakota Formation angiosperm leaf megafossils, I chose to use species density with modification (see next paragraph) of the original definition, which is the number of species per specified collection area (Hurlbert, 1971). This concept is the most commonly used measure of species richness and is especially

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204 favored by botanists because it provides an instantly comprehensible expression of diversity (Bunce and Shaw, 1973; Kershaw and Looney, 1985; Magurran, 1988). I define species density as the number of species per locality for the following reasons: (1) all the localities, e.g., BraunÂ’s Ranch (Figure 14) and Hoisington III localities (Figure 15) of Kansas, Rose Creek I locality of Nebraska (Figure 16), Courtland I locality (Figure 16), Minnesota, are small clay pits w ith an angiosperm fossil collection area of no more than 400 square meters (Dilcher, personal communication). It can be assumed that the specimens were collected in fixed (to some extent, equal) areas; (2) the numerical species richness index, which is defined as the number of species per specified number of individuals or biomass (Kempton, 1979) was not selected because of the difficulty of obtaining accurate number of individuals; and (3) the species density concept is intuitively simple to apply and understand. For diversity analysis, I use PAST (PAleontological STatistics), a comprehensive software package for executing a range of standard numerical analysis and operations used in quantitative paleontology. It was developed by Hammer et al. (2001). I chose to use PAST because it runs on standard Windows computers, is simple to use, and is available free of charge. It includes many functions such as integrating spreadsheet-type data entry with univariate and multivariate statistics, curve fitting, time-series analysis, data plotting, and simple phylogenetic analysis, many of which are specific to paleontology and ecology. Diversity Analysis of the Dakota Flora Overall Diversity of the Dakota Flora For the entire Dakota Flora, species richness (number of unique species) increases inevitably with the sample size (number of specimens collected) and/or sampling effort

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205 (Figure 7). However, this trend does not apply to separate localities, i.e., species density of each locality shows no direct correlation with the number of specimens collected from that locality (Figure 8). Of the 6,000 specimens collected from the Dakota Formation (Table 1), 87 species of 40 genera have been recognized from 2,670 identifiable angiosperm leaf megafossils. Observation of LesquereuxÂ’s type specimens stored in the Paleobotany Division at the National Museum of Natural History (NMNH), Smithsonian Institution (personal observation) indicates that there are at least 50 unique (different from the collections stored in the Paleobotany Division at the Florida Museum of Natural HistoryFLMNH) leaf types. Other observations on the Dakota Formation specimens stored in the Museum of Natural History at Kansas University and Steinberg Museum of Natural History in Kansas indicates that there are at least 20 unique (different from those stored at FLMNH and NMNH) leaf types (Margaret La ndis, personal communication). Adding all these together, a conservative estimation of angiosperm species from the Dakota Flora would be at least 150 species, which is neither as high as that proposed Lesquereux (1892, 437 species), nor as low as suggested by Lidgard and Crane (1988, about 20 species). Figure 9 and Table 6 show the diversity indices for each locality. Five (Dominance, Simpson, Menhinic, Shannon, and FisherÂ’s alpha, see Appendix 3 for definition of these indices) of six indices indicate that the Courtland I locality (23 species) is the most diverse, followed by the Hoisington III locality (27 species). Only the Margalef index indicates that the Hoisington III locality is slightly more diverse than the Courtland I locality. Four indices (Dominance, Simpson, Menhinic, and Shannon) indicate that the BraunÂ’s Ranch locality (23 species) is the least diverse. Though

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206 Margalef and Fisher’s alpha indices indicate that the Braun’s Ranch locality is more diverse than the Pleasant Dale and Springfield localities, that are probably resulted from the under-collection of these two localities. Comparisons Among Localities It is improper to assume that the Hoisington III locality is the most diverse locality because the number of species will i nvariably increase if more specimens are collected from Springfield or Pleasant Dale. It is also incorrect to simply re-scale the smallest collection by a constant multiplier because the relationship between the number of specimens and the number of species is not linear (Figure 8). To address this problem of comparing the species richness between different localities, I use PAST’s rarefaction function to calculate the expected species richness based on random subsample of specimens. Rarefaction is an algorithm devised by Sanders (1968) for calculating the expected species richness based on random subsamples of individuals when comparing the species richness of different habitats in a study of marine benthic communities. The “rarefied” curve for each locality is plotted on a graph that has number of specimens on the abscissa and the number of species on the ordinate (Figure 10). The rarefaction curve for the Braun’s Ranch locality lies significantly below those of other localities except for that of Springfield. The curve for the Hoisington III locality seems to be higher than all the other localities, with possible exception of the Courtland I locality, but this can be verified only if enough specimens are collected from both Courtland I and Hoisington III localities. These cannot be explained by the number of specimens collected from these localities. The number of species from the Dakota Formation invariably increases with the number of specimens collected (Figure 7), there is no direct correlation between the number of species and the number of specimens

PAGE 215

207 collected from each individual locality (Figure 8). The BraunÂ’s Ranch locality has the largest number of specimens (1,354) collected, but this locality only yields 23 species. The Hoisington III locality has only 395 specimens, only about one third of the BraunÂ’s Ranch locality, but contains 25 species (Table 6). In the Courtland I locality, Minnesota, 189 specimens, which is only 14% of the number of specimens from the BraunÂ’s Ranch locality, were collected, but this locality yields the same number of species. For now, it can be concluded that the Hoisington III locality is possibly the most diverse in species richness. Two localities, the Springfield and Pleasant Dale locality, are obvious undercollected. More collections from these localities and potentially others (for example, one or two localities from Iowa State, see Figure 1.) are critically needed in order to assess their species diversity levels. Two association similarity indices (Table 7, Dice similarity index: 0.228571; Table 7, Jaccard similarity index: 0.129032) indicate that the Courtland I locality, Minnesota, is the most similar to the Pleasant Dale locality, Nebraska, while the other two indices (Table 8, Simpson similarity index: 0.4; Table 9, Raup-Crick similarity index: 0.5775) indicate that the Hoisington III locality, Kansas, and the Springfield locality, Nebraska are more similar than others. Of the 12 species identified from the Pleasant Dale locality (Appendix A), four species (33% of total number of species), i.e., Jarzenia reticulatus , Manchesterii macrophylla , Rogersia kansense , and Trochodendroides rhomboideus are shared with the Courtland I locality (17% of 23 species). Of the 7 species recognized from the Springfield locality (Appendix A), two species i.e., Pabiania variloba , Sapindopsis retallackii , are shared with the Hoisington III locality. However, these observations could be misleading because all the four similarity

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208 indices are under the assumption of equal sampling conditions. The comparisons among BraunÂ’s Ranch, Courtland I, Hoisington III, and Rose Creek I locality tend to yield more reasonable results because the sampling size of these four localities are more or less equal. Excluding the Springfield and Pleasant Dale localities, all four association similarity indices (Table 7, Dice: 0.204082; Table 7, Jaccard: 0.113636; Table 8, Simpson: 0.227273; Table 9, Raup-Crick: 0.0975; Figure 11) indicate that the Rose Creek I locality (total of 22 species; Appendix A.), Nebraska, and the Hoisington III locality (total of 27 species; Appendix A), Kansas, are the most similar, with five species, i.e., Crassidenticulum decurrens , Pabiania variloba , Pabiania groenlandic a, Anisodromum wolfei , and Meiophyllum expansolobum shared by both localities, which means that 23% of the species from Rose Creek I locality is shared with the Hoisington III locality (only 18.5% of the species from the Hoisington III locality). The two most diverse localities, Hoisington III and Courtland I, have four species in common, i.e., Jarzenia kanbrasota , Wolfiophyllum pfaffiana , Dicotylophyllum leptovena , and Credneria cyclophylla . In percentage, these four species represent 17% from Courtland I locality and 15% from Hoisington III locality. Of the 87 species recognized, none has occurrence in more than three localities (Appendix A). Only six species, i.e., Jarzenia kanbrasota , Crassidenticulum decurrens , Pabiania variloba , Rogersia kansense , Sapindopsis retallackii , and Meiophyllum expansolobum are shared by three localities (Appendix A). Cluster analysis (Figure 11) based on Dice, Jaccard, Simpson, BaryCurtis, and Raup-Crick coefficient indices i ndicates that Hoisington III and Rose Creek I tend to group together (share more species). Geographically, the BraunÂ’s Ranch locality is close to Hoisington III and Rose Creek, but it shows the least similarity with them.

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209 Figure 11 also shows that no two localities share more that 25% species (excluding the two under-collected localities, i.e., Springfield and Pleasant Dale) Diversity Within Individual Localities Species distribution within each locality is uneven. There are always several species locally dominant at different localities. For example, five species, i.e., Eoplatanus serrata (718 specimens), Rogersia kansense (200), Rogersia parlatorii (195), Crassidenticulum decurrens (125), Crassidenticulum trilobus (58), are the dominant members from the BraunÂ’s Ranch locality. Likewise, four species, i.e., Pabiania variloba (150), Crassidenticulum decurrens (130), Longstrethia varidentata (98), Pandemophyllum kvacekii (70) are the dominant elements from the Rose Creek I locality. Similarly, several species dominate other localities (Figure 12 and Table 10) with the exception of the Courtland I locality, which has no individual species exceeding 50 specimens. The BraunÂ’s Ranch locality (with the highest dominance index of 0.3344, see Table 6) is possibly the least diverse because five species, i.e., Crassidenticulum decurrens, Crassidenticulum trilobus, Rogersia kansense, Rogersia parlatorii, Eoplatanus serrata, represent almost 95% of total identifiable specimens from this locality (Table10 and Figure 12). Considering the entire Dakota Flora including all six localities, 16 dominant (Table 10) species represent 83% percent of 2670 identifiable specimens collected. Most of these dominant elements belong to the Magnoliales, Laurales, and Proteales. Effects on the Diversity Pattern of the Dakota Flora Paleoenvironmental interpretation of the six localities by various authors (Table 1) indicates that angiosperm leaf megafoss il are formed under different environments. As we can see, the resolution of age determination of these localities is not high enough

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210 to place these localities in a chronological order in the stratigraphic column, which makes it difficult to assess the effects of time on the evolution/diversity of the Dakota Flora. At present, the little species overlap can best be explained by the environments. Similar environments, even though separated by a great geographical distance (or with a great time difference with similar paleoclimate condition, see discussion below), tend to have more similar taxa than two different environments with a distance of only several kilometers (Kvacek and Dilcher, 2000). The high diversity angiosperm leaf megafossils at different localities is in conflicts with the pollen record (Farley and Dilcher, 1986; Dilcher and Farley, 1988), which indicates a high percentage of fern spores and gymnosperm pollen. This was interpreted as resulted from the dominance of ferns and gymnosperms in the regional flora and the dominance of angiosperms at local environments (Skog and Dilcher, 1994; Kvacek and Dilcher, 2000). The Dakota Formation was also suggested as formed at a time just prior to the wide dispersal of angiosperm pollen by wind so that few angiosperm pollen are produced relative to the large number of pollen and spores produced by the gymnosperms and ferns (Kvacek and Dilcher, 2000). All these suggest that the high diversity of angiosperms from different localities are controlled by environment, rather than sampling effect (Farley and Dilcher, 1986), which further suggests successful competition of angiosperms with gymnosperms and ferns during that time (Kvacek and Dilcher, 2000). Taphonomic Effects on the Diversity of Angiosperm Leaf Megafossils Angiosperms, especially deciduous dicot angiosperms, consist of multiple organs such as leaves, flowers, fruits, seeds, stems, roots, etc. Most plant remains preserved as fossils were transported some distance except those preserved as coals and peats (Gastaldo, 1992). Unlike trunks, seeds, and pollen grains that may be reworked a number

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211 of times before final deposition (Liu and Gastaldo, 1992), leaves tend to decay fairly rapidly (depending on the species). Burnham (1993a) demonstrated that samples of modern forest litter represent very small number (tropical and subtropical samples) to about 75% (temperate samples) of the source tree species larger than 10 cm diameter at breast height within the surrounding hectare. The investigation of a paratropical floodplain forest in southern Mexico (Burnha m, 1989) indicates that litter samples from levees and back levees tend to reflect the local flora with greater accuracy than do channel samples, but levees are not good sites for preservation because of oxidation through subaerial exposure and bioturbation by roots (Gastaldo, 1989; Gastaldo et al., 1989). These results indicate that when reconstructing species richness in the plant fossil record, a “climatic filter” should be applied to the estimation of diversity. Meldahl et al. (1995) reported that the long-term (accumulating over several months) autochthonous leaf assemblage can reflect the surrounding community with fair accuracy and that taxonomic relative abundance in the leaf assemblage is primarily controlled by the relative abundance of trees in the vicinity of the accumulation site. Short-term (accumulating over several days) assemblages are inconsistent with the records of surrounding community. No exceptional excursion produced by autumn abscission peak in taxonomic relative abundance in leaf assemblages is observed. These results (Burnham and Wing, 1992; Burnham, 1993a; Meldahl et al., 1995) imply that autochthonous long-term assemblages can accurately record the taxonomic composition and the relative abundance of taxa in the immediate surrounding community. The rates and patterns of leaf fall vary depending on the leaf weight, leaf area and leaf petiole, but most leaves tend to disperse in air within a distance equal to the height of

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212 the source plant (Ferguson, 1985). Storm events may transport leaves to considerable distances (Spicer, 1989). Leaves of herbaceous taxa tend to wither and rot on their parent plant. Their chance of being preserved as foss ils is often a function of rapid events such as floods and volcanic ashes (Burnham and Spicer, 1986). After falling on the ground, leaves tend to move by rolling and salutation (Spicer, 1989), however, little ground transport occurs, as Ferguson (1985) noted that only one out of 500 leaves has moved 2 mm after 98 days. Biological degradation plays a significant role, depending on climatic regimes. It has been documented that 50% of leaf fall is degraded by fungal, bacterial, and othe r microbial activity in temperate and tropical regions (Burnham, 1993b). The interpretation of environments for the Dakota Formation localities varies, but predominantly lake or swamp (Table 1), e .g., BraunÂ’s Ranch, Kansas (Figure 72), fresh water lake on an alluvial floodplain (Retall ack and Dilcher, 1981; Farley and Dilcher, 1986); Hoisington III, Kansas (Figure 73), fresh-water lake or brackish water lagoon environment with river influence (Retallack and Dilcher, 1981; Skog and Dilcher, 1992, 1994); Rose Creek I, Nebraska (Figure 74), a coastal swamp with periods of inundation with brackish water and tidal influences (Farley and Dilcher, 1986; Upchurch and Dilcher, 1990). Leaves of different sizes are exquisitely preserved without any orientation (Figure 75) indicating no sorti ng mechanism was involved. Leaves of many species possess very large leaf sizes ( Meiophyllum expansolobum, up to 22 cm long by 20 cm wide; Liriophyllum kansense, 18.5 cm long by 20 cm wide; Pabiania cf. P. groenlandica, 13.5 cm long by at least 20 cm wide; and other platanoid and Sapindopsis type species) and show no signs of mechanical abrasion. All these imply that the leaves

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213 in these assemblages had probably undergone little or no transportation before preservation. Conclusions, Problems, and Perspectives In this project, 87 angiosperm species are recognized from the Dakota Formation and there are about 7 to 27 species from each locality. The diversity of the Dakota Flora probably was neither as high as that proposed by Lesquereux (1892), nor as low as that suggested by Lidgard and Crane (1988). I propose a conservative total estimate of probably about 150 to 200 species (including LesquereuxÂ’s collections) from the Dakota Flora during the mid-Cretaceous. There is less than 25% of species overlap between any two localities except between Pleasant Dale and Courtland I localities, which may be the result of insufficient collection of the Pleasant Dale locality. At pr esent, the high diversity of angiosperms that is locality specific can best be interpreted as the result of unique environments (Retallack and Dilcher, 1986). At this time, there is no reliable dating of these megafossil localities, which also could account for species difference if the time for the deposition of the flora extended over many million years. Most of the dominant elements of the Dakota Flora belong to Magnoliales, Laurales, and Proteales. Elements from these three orders are also common dominant members of floras at individual localities. As in modern ecological diversity analysis, questions such as what sample size (number of specimens collected) should be adopted and the amount of area sampled (number of localities collected) in diversity measurement is always a problem. Though the problem becomes simpler when only the species richness is being measured (Magurran, 1988). Coupled with taphonomical processes, this problem seems to affect

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214 diversity measurements even more. Intensive collections will greatly improve the record of species present and reduce any problems resulting from sampling, though it may not solve this problem completely. In order to assess diversity of the Dakota Flora, more collections, especially from two existing localities (i.e., Pleasant Dale and Springfield of Nebraska) and potentially from localities (Figure 1) in Iowa, are critically needed. Since this research was focused on mudstone and shale specimens from the Dakota Formation, it is biased against sandstone specimens such as those from Lesquereux’s (1892) collections. Table 3. Comparisons of several entire-margined leaves from the Dakota Formation species Leaf shape 2º venation number of 2º veins loops near margin Intercostal region Intersecondary veins Tertiary veins Rogersia potteri elliptic festooned brochidodromous 10 two series well defined present percurrent Wolfiophyllum pfaffiana very narrow elliptic eucamptodromous 8 no no common not observed Rogersia kansense linear oblong brochidodromous >10 two series, elongate area well defined present percurrent, more or less irregular Rogersia parlatorii oblong, lorate to linear brochidodromous >10 irregular elongate and admedially oriented common intergrading with 2º and 4º Wolfiophyllum heigii lorate or linear eucamptodromous 10 to 12 forking no present percurrent or exmedially ramified (branches oriented toward the margin), course sinuous Hickeyphyllum imhofia narrow obovate to oblanceolate festooned brochidodromous >10 two series well defined present, composite random or orthogonal reticulate Hickeyphyllum sandersia narrow elliptic brochidodromous 8 one well defined common, simple irregular, oriented parallel to leaf margin Rogersia lottii narrow elliptic festooned brochidodromous 20 one well defined present, simple thin

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215 Table 4. Comparisons of Crassidenticulum decurrens , Crassidenticulum landisae , Crassidenticulum trilobus , and Yangia glandifolium Species Primary venation Secondary venation Intersecondary veins Tertiary venation Tooth type Marginal thickening on teeth Crassidenticulum decurrens pinnate fundamentally craspedodromous, but with tendency to form loops and/or curve apically, spacing close, irregular common, originate from primary vein or secondary veins. irregularly reticulate chloranthoid well developed Crassidenticulum landisae pinnate craspedodromous, but may be semicraspedodrom ous at basal portion of lamina present, composite, originate from primary vein tending to be percurrent typically one exmedial branch from secondary vein near margin terminate at apical side of tooth. 4 to 5 teeth per cm well developed, may be deciduous Crassidenticulum trilobus actinodromous fundamentally craspedodromous, but with tendency to form loops and/or curve apically, spacing sparse, irregular common, originate from primary vein tending to be percurrent typically three veins terminate at tooth apex. 5 to 10 teeth per cm well developed, probably deciduous Yangia glandifolium pinnate festooned brochidodromous common, simple, thin, tending to be percurrent vein behavior over tooth not observed. serration types convexconvex. possibly not well developed

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216 Table 5. Comparisons of several Cretaceous aquatic plant leaves from North America Shape Base Margin Primary venation Number of primary veins Orientation of primaries Floating structure Orientation of meshes Menispermites virginiensis orbicular peltate? undulate or obscurely crenulate actinodromous 10 distally and proximally curved not observed irregular Menispermites dentatus (Heer, 1883) orbicular peltate crenulate actinodromous 14 distally curved except medial not observed percurrent veins between primary veins observed Menispermites grandis (Lesq., 1883) round peltate entire or undulate actinodromous 9 distally curved except medial not observed percurrent veins between 1 veins Nelumbites floatii orbicular auriculate crenate basal actinodromous 9 distally curved except medial yes five to seven-sided meshes with long axes radially oriented Nelumbites crenata orbicular peltate eccentric crenate actinodromous 3 radially oriented yes? meshes irregular in shape and size with long axes radially oriented Nelumbites sp. orbicular or slightly oblate peltate central entire actinodromous 11 distally and proximally oriented not observed meshes both irregular in shape and size, Nelumbites extenuinervis Upchurch et al., 1994 orbicular peltate entire actinodromous 5 to 6 radially oriented no radially elongate Nelumbites cf. N. minumus (Vakhrameev) Upchurch et al., 1994 orbicular peltate crenate actinodromous 7 (one medial, three pairs if laterals) tending to be radially oriented no isodiametric to exmedially elongate

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217 Table 6. Diversity indices for the six localities from the Dakota Formation Braun's Ranch Hoisington III Rose Creek Pleasant Dale Springfield Courtland I Taxa 23 27 22 12 5 23 Number of specimens 1354 395 506 151 75 189 Dominance 0.3344 0.14406 0.21189 0.22074 0.30809 0.11509 Shannon index 1.486 2.3026 1.8383 1.7753 1.2786 2.5138 Simpson index 0.6656 0.85594 0.78811 0.77926 0.69191 0.88491 Menhinic 0.62506 1.3585 0.97802 0.97655 0.57735 1.673 Margalef 3.051 4.3486 3.3727 2.1924 0.92646 4.1971 Fisher alpha 3.9359 6.5631 4.6906 3.0627 1.2059 6.8631 Table 7. Dice (lower left) and Jaccard (upper right) association similarity indices Braun's Ranch Hoisington III Rose Creek Pleasant Dale Springfield Courtland I Braun's Ranch 1 0.041667 0.022727 0.060606 0 0.045455 Hoisington III 0.08 1 0.113636 0.083333 0.066667 0.086957 Rose Creek 0.044444 0.204082 1 0.030303 0.038462 0.071429 Pleasant Dale 0.114286 0.153846 0.058824 1 0.0625 0.129032 Springfield 0 0.125 0.074074 0.117647 1 0 Courtland I 0.086957 0.16 0.133333 0.228571 0 1 Table 8. Simpson association similarity index Braun's Ranch Hoisington III Rose Creek Pleasant Dale Springfield Courtland I Braun's Ranch 1 Hoisington III 0.086957 1 Rose Creek 0.045455 0.227273 1 Pleasant Dale 0.166667 0.25 0.083333 1 Springfield 0 0.4 0.2 0.2 1 Courtland I 0.086957 0.173913 0.136364 0.333333 0 1

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218 Table 9. Raup-crick association similarity index Braun's Ranch Hoisington III Rose Creek Pleasant Dale Springfield Courtland I Braun's Ranch 1 0.0025 0.0025 0.195 0.0725 0.0075 Hoisington III 1 0.0975 0.23 0.5775 0.015 Rose Creek 1 0.055 0.3725 0.0075 Pleasant Dale 1 0.5725 0.575 Springfield 1 0.0875 Courtland I 1 Table 10. Number of specimens of dominant species from each locality Braun Hoisington III Rose Creek Pleasant Dale Springfield Courtland I Crassidenticulum decurrens 125 130 Crassidenticulum trilobus 58 Credneria cyclophylla 36 Eoplatanus serrata 718 Liriophyllum kansense 30 Longstrethia varidentata 98 Meiophyllum expansolobum 54 Nelumbites crassinervum 30 Nelumbites fluitus 35 Pabiania groenlandica 34 Pabiania variloba 56 150 Pandemophyllum kvacekii 70 Rogersia kansense 200 43 38 Rogersia parlatorii 195 50 Sapindopsis bagleyae 110 Sapindopsis retallackii 28

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219 Genera Magno liids 33% Others 49% Proteales 18% Species Magno liids 39% Others 45% Proteales 16% Figure 5. Dakota floristic composition. Note that 51% of identified genera (top) and 55% of identified species (lower) were assigned to Magnoliids and Proteales.

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220 Figure 6. Modern vs. fossil taxonomic groups fo r the Dakota Flora. Note that no modern genera is identified. 0 500 1000 1500 2000 2500 3000 SPCRHB Commulative number of species Commulative number of specimens Figure 7. The relationship between number of species and number of specimens collected from the Dakota Formation. S-Springfield, NE; P-Pleasant Dale, NE; C-Courtland I, MN; R-Rose Creek, NE; H-Hoisington III, KS; B-BraunÂ’s Ranch, KS. Bar for number of species is exaggerated ten times in order to show the trend. 0 10 20 30 40 50 60 70 80 90 100 ClassOrderFamilyGenus% Modern vs. Fossil Fossil Modern

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221 0 200 400 600 800 1000 1200 1400 Springfield Pleasant Dale Courtland I Hoisington III Rose Creek I Braun's Ranch Number of species identified from each locality Number of specimens collected from each locality Figure 8. Number of specimens collected vs. number of species identified from each locality. Orange bars represent number of specimens and blue bars represent number of species. Species bars are exaggerated 10 times for comparisons.

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222 Figure 9-Graphic view of diversity indices for different localities. Fisher alpha 0 1 2 3 4 5 6 7 8 BHRPSC Shannon index 0 0.5 1 1.5 2 2.5 3 BHRPSC Margalef 0 1 2 3 4 5 BHRPSC Simpson index 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 BHRPSC Menhinick 0 0.5 1 1.5 2 BHRPSC Dominance 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 BHRPSC

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223 0 5 10 15 20 25 30 050010001500 Number of specimensNumber of species Braun's Ranch Hoisington III Rose Creek I Pleasant Dale Springfield Courtland I Figure 10. Rarefaction curves for the six localities of the Dakota Flora.

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224 Dice coefficient index Jaccard Jaccard coefficient index Figure 11. Cluster analysis based on different association similarity indices (See Appendix C for the definition of indices ). S-Springfield, NE; H-Hoisington III, KS; R-Rose Creek, NE; P-Pleasant Dale, NE; C-Courtland I, MN; BBraunÂ’s Ranch, KS. 1 2 3 4 5 6 7 0. 1 0. 2 0. 3 0. 4 0. 5 0. 6 0. 7 0. 8 0. 9 1 Similarity S H R P C B 1 2 3 4 5 6 7 0. 1 0. 2 0. 3 0. 4 0. 5 0. 6 0. 7 0. 8 0. 9 1 Similarity S H R P C B

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225 Simpson coefficient index. Bary-Curtis coefficient index Figure 11. (cont.) 1 2 3 4 5 6 7 0. 1 0. 2 0. 3 0. 4 0. 5 0. 6 0. 7 0. 8 0. 9 1 Similarity S H R P C B 1 2 3 4 5 6 7 0. 1 0. 2 0. 3 0. 4 0. 5 0. 6 0. 7 0. 8 0. 9 1 Similarity H S R P C B

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226 Raup-Crick coefficient index Figure 11. (cont.) 1 2 3 4 5 6 7 0. 1 0. 2 0. 3 0. 4 0. 5 0. 6 0. 7 0. 8 0. 9 1 Similarity H S R P C B

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227 0% 20% 40% 60% 80% 100% Other species (%) 41211.538.56361 Dominant species (%) 968888.561.53739 BHRPSC Figure 12. Percentage of number of specimens of dominant species vs. that of other species at each locality. B-BraunÂ’s Ranch, KS; H-Hoisington III, KS; R-Rose Creek, NE; P-Pleasant Dale, NE; S-Springfield, NE; C-Courtland I, MN.

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Figure 13. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Eoplatanus serrata Schwarzwalder and Dilcher 1986 1. UF15709-31211. Petiole with inflated base. Bar = 5 mm. 2. UF15709-11998. General view of leaf shape. 3. UF15709-39511. An immature leaf. Note glandular heads (hydathodes) on apices of teeth and development of secondary venation. Bar = 2 mm. 4. UF15709-23268. General view of leaf shape. 5. UF15709-3946. An immature leaf with stipules attached. 6. Enlargement of Figure 13, 5 to show stipule (indicated by arrow). Bar = 2 mm. 7. UF15709-31176. Possible variation of leaf shape. 8. UF15709-11885. Leaf with revolute margin. 9. UF15709-23355. Compound tooth, an occasional variation of tooth type. 10. Enlargement of Figure 13, 9 to show tooth type. Note secondary veins, looping tertiary veins in the tooth, and hydathodes. Bar = 2 mm.

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Figure 14. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Eoplatanus serrata Schwarzwalder and Dilcher 1986 1. UF15709-4511. Leaf with deep lobes. 2. Enlargement of Figure 14, 1 to show details of venation pattern on the tooth and near margin. Note three veins go into a tooth, one originated from the exmedial side of secondary vein and two from looping marginal veins. Bar = 2 mm. 3. UF15709-3120. A variation of leaf shape. 4. Enlargement of Figure 14, 3 to show tooth type. Note fungal growth on leaf lamina. Bar = 2 mm. 5. UF15709-4529. Leaf with fungal growth before preservation. 6. Enlargement of Figure 14, 5 to show reinforced margin on sinus and embraced veins below sinus. Bar = 2 mm. 7. Enlargement of Figure 14, 5 to show inverted ‘V’ shaped veins between medial and lateral primary veins. Note also different stages of fungal growth. Bar = 2 mm.

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Figure 15. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Eoplatanus serrata Schwarzwalder and Dilcher 1986 1. UF15709-14836. A possible variation of leaf shape with five lobes. 2. Enlargement of Figure 15, 1 to show tooth type. Note that one secondary vein and two lateral marginal looping veins entering the tooth. Bar = 3 mm. Aspidiophyllum denticulatus Wang sp. nov. 3. UF15709-23279. A leaf showing secondary and tertiary venation pattern. Note the exmedial branches of secondary veins. 4. UF15709-31177. Showing secondary venation pattern. 5. Enlargement of Figure 15, 4 to show tooth type. Note that one exmedial branch of secondary veins and two marginal veins (tertiary order) entering the tooth. Bar = 2 mm. Eoplatanus serrata Schwarzwalder and Dilcher 1986 6. UF15709-23346. Variation of leaf base. Glandilunatus minnesotense Wang sp. nov. 7. UF15709-11107. Showing general leaf shape and secondary venation. Note all secondary veins and their branches terminate on teeth. Dicotylophyllum fragilis Wang sp. nov. 8. UF15709-30123. A leaf of a possible aquatic plant. Note the slender petiole and thin leaf texture. 9. Enlargement of Figure 15, 8 to show a possible peltate base. Bar = 5 mm.

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Figure 16. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Eoplatanus serrata Schwarzwalder and Dilcher 1986 1. UF15709-24940. A fruiting axis with five infructescences attached. Note two dispersed fruits on the right side of the axis. 2-3. Enlargement of dispersed fruits. Note the absence of dispersal hairs. Bar = 2 mm. 4. UF15709-3910. A fruiting axis with at least 23 infructescences. 5. UF15709-24936. A fruiting axis with 8 infructescences. This specimen possibly represents the ultimate end of the axis. 6. UF15709-24005. A fruiting axis with at least 17 infructescences. 7. UF15709-29580. A fruiting axis with at least 13 infructescences. Note the alternate arrangement of infructescences on the axis. 8. UF15709-23970. An infructescence showing attached fruits. 9. UF15709-23497. A mature staminate axis with stamens already shed. 10. UF15709-3139. A mature staminate axis with stamens already shed. At least 14 staminate inflorescences on the right axis. Note the two axes attached together. 11. UF15709-23911. A fruiting axis with all fruits already dispersed. 12. UF15709-23540. A fruiting axis with 12 infructescences. Note the close arrangement of fruiting heads. 13. UF15709-24922. Two infructescences with some fruits still attached. Bar = 2 mm. 14. UF15709-3122. A fruiting axis and an immature leaf. 15. Enlargement of the immature leaf of Figure 16, 14 to show secondary venation pattern and glandular teeth. Bar = 3 mm.

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Figure 17. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Rogersia parlatorii Fontaine 1889 1. UF15709-16269. General view of leaf shape. 2. Enlargement of Figure 17, 1 to show venation pattern. Bar = 5 mm. 3. UF15709-16497Â’. Leaf with acuminate apex. 4. UF15709-16511. Leaf with short petiole and acuminate apex. 5. UF15709-16357. General view of leaf shape. 6. Enlargement of Figure 17, 5 to show venation pattern. Bar = 5 mm. Wolfiophyllum heigii Wang sp. nov. 7. UF15709-16344. General view of a small leaf. Note basal secondary veins extending a long distance along leaf margin and indistinct demarcation of lamina and petiole at the base. 8. UF15709-16379. General view of leaf shape. 9. Enlargement of Figure 17, 8 to show venation pattern. Note thin secondary veins. Rogersia parlatorii Fontaine 1889 10. UF15709-16458. General view of leaf shape. Note short petiole and acuminate apex. Wolfiophyllum heigii Wang sp. nov. 11. UF15709-16301. Upper portion of leaf to show irregular venation. 12. UF15709-16308. General shape of leaf. Note secondary venation pattern and decurrent lamina on the petiole.

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Figure 18. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Rogersia parlatorii Fontaine 1889 1. UF15709-16267. General view of leaf shape. 2. Enlargement of apical portion of Figure 18, 1 to show venation. Bar = 3 mm. 3. Enlargement of middle portion of Figure 18, 1 to show venation. Bar = 3 mm. 4. Enlargement of left basal portion of Figure 18, 1 to show venation. Bar = 3 mm. 5. UF15709-11865. Middle and basal portion of leaf. Note short petiole. 6. UF15709-16259. Specimen showing short petiole. 7. UF15709-16512Â’. General view of leaf shape. 8. UF15709-16275. Middle and basal portion of leaf. 9. Enlargement of Figure 18, 8 to show venation pattern. Bar = 3 mm. 10. UF15709-11862. General view of leaf shape. 11. Enlargement of Figure 18, 10 to show venation pattern. Bar = 3 mm.

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Figure 19. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Rogersia lottii Wang sp. nov. 1. UF15709-12524Â’. General view of leaf shape. Note relatively strong secondary veins. 2. UF15709-12524. Counterpart of Figure 19, 1. 3. Enlargement of Figure 19, 2 to show venation pattern. Note well-defined intercostal region. Bar = 3 mm. Hickeyphyllum sandersia Wang sp. nov. 4. UF15709-16487Â’. Middle and apical porti on of leaf. Note rounded apex. 5. UF15709-16487. Counterpart of Figure 19, 4. 6. Enlargement of Figure 19, 5 to show venation pattern. Note well-defined secondary venation. Bar = 5 mm. Wolfiophyllum heigii Wang sp. nov. 7. UF15709-24897. General view of leaf shape. Bar = 5 mm. 8. UF15709-24897Â’. Counterpart of Figure 19, 7. Bar = 5 mm. Hickeyphyllum imhofia Wang sp. nov. 9. UF15709-16439. General view of leaf shape. 10. Enlargement of Figure 19, 9 to show venation pattern. Note reinforced leaf margin. Bar = 5 mm.

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Figure 20. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Dischidus quinquelobus Wang sp. nov. 1. UF15709-11883Â’. General view of leaf shape. 2. UF15709-11883. Counterpart of Figure 20, 1. 3. Enlargement of Figure 20, 1 to show the teeth. Note the glandular head (hydathode) on tooth apex and the craspedodromous secondary veins and looping higher order veins in the teeth. Bar = 5 mm. 4. Enlargement of petiole base in Figure 20, 1 to show the stipules (indicated by arrow). Bar = 5 mm. Dicotylophyllum braunii Wang sp. nov. 5. UF15709-14841. General view of leaf shape. 6. Enlargement of Figure 20, 5 to show venation pattern. Bar = 5 mm.

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Figure 21. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Crassidenticulum trilobus Wang sp. nov. 1. UF15709-11892. A leaf with two lobes observed. 2. Enlargement of Figure 21, 1 to show teeth. Bar = 5 mm. 3. UF15709-16553. Specimen showing attenuate apex. 4. Enlargement of Figure 21, 3 to show structurally reinforced lobe sinus. Bar = 5 mm. 5. UF15709-11894. Specimen with three lobes. 6. Enlargement of Figure 21, 5 to show teeth on leaf base and sinus. Bar = 5 mm. 7. UF15709-11108. Specimen showing leaf shape. Note two pairs of thorns observed on the petiole. 8. Enlargement of Figure 21, 7 to show thorns on petiole base. Bar = 5 mm.

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Figure 22. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Crassidenticulum trilobus Wang sp. nov. 1. UF15709-16556. Specimen with two lobes observed. 2. Enlargement of Figure 22, 1 to show teeth. Seta still attached on tooth apex. Bar = 5 mm. 3. UF15709-16409. Specimen with petiole observed. 4. UF15709-16409Â’. Counterpart of Figure 22, 3. Medial lobe with obtuse apex. 5. Enlargement of Figure 22, 4 to show three pairs of thorns observed on petiole. Bar = 5 mm. 6. UF15709-3998. Specimen showing obtuse lobe apices.

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Figure 23. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Rogersia parlatorii Fontaine 1889 1. UF15709-11874. Basal portion of leaf. Kladoneuron gooleria Wang sp. nov. 2. UF15709-12511Â’. General view of leaf shape. 3. UF15709-12511. Counterpart of Figure 23, 2. 4. Enlargement of Figure 23, 3 to show venation. Note thin secondary veins. Bar = 5 mm. Landonia mullerii Wang sp. nov. 5. UF15709-16465. General leaf shape. Crassidenticulum trilobus Wang sp. nov. 6. UF15709-24157. Specimen with two lobes. 7. Enlargement of Figure 23, 6 to show structurally reinforced sinus. Bar = 5 mm. 8. Enlargement of upper right lamina in Figure 23, 6 to show teeth. Bar = 5 mm.

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Figure 24. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Credneria quadratus (Lesquereux) Wang comb. nov. 1. UF15709-14835. Specimen showing orbicular leaf shape, primary venation, and secondary venation. 2. Enlargement of Figure 24, 1 to show the auricular base, which gives a peltate appearance. Bar = 5 mm. 3. Enlargement of Figure 24, 1 to show tertiary and quaternary venation. Bar = 5 mm. Dicotylophyllum sp. 4. UF15709-16505. Basal portion of leaf. 5. Enlargement of Figure 24, 4 to show fine venation. Note reticulate tertiary veins. Bar = 5 mm. 6. UF15709-16505Â’. Counterpart of Figure 24, 4. Note obtuse apex.

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Figure 25. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Crassidenticulum decurrens Upchurch and Dilcher 1990 1. UF15709-11869. Specimen showing lateral and ultimate leaflets attached to the petiole and the petiolules of other associated leaflets. 2. Enlargement of Figure 25, 1 (upper left portion of lamina) to show secondary venation and teeth. Bar = 5 mm. 3. Enlargement of Figure 25, 1 (petiole) to show the winged nature of the petiole, and petiolules with even-pinnate arrangement of the leaflets. Bar = 5 mm. 4. UF15709-16560. Distorted leaflet to show very narrow elliptic shape. 5. UF15709-16536. Specimen showing narrow elliptic leaflet. 6. UF15709-16306Â’. Basal portion of leaflet s howing the asymmetrical base typical of lateral leaflets. 7. Enlargement of Figure 25, 6 (upper right portion of leaflet) to show looping secondary venation and teeth. Bar = 5 mm. 8. UF15709-20236. Stout primary vein and broad angles of secondary veins. 9. UF15709-20236Â’. Counterpart of Figure 25, 8. 10. Enlargement of Figure 25, 9 to show secondary and tertiary veins leading to the sinuses of the leaf margin. Bar = 5 mm.

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Figure 26. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Crassidenticulum decurrens Upchurch and Dilcher 1990 1. UF15709-16545. Leaflet showing decurrent laminar tissue on petiole and stout primary vein. 2. UF15709-16546. General shape. Perhaps typical of terminal leaflet compared with Figure 25, 6. 3. Enlargement of Figure 26, 2 to show secondary venation and teeth. Bar = 5 mm. Wolfiophyllum daphneoides (Lesquereux) Wang comb. nov. 4. UF15709-25002. Middle portion of leaf. 5. UF15709-16491. Basal and middle portion of leaf. 6. Enlargement of middle portion of Figure 26, 5 to show venation. Note stout primary vein, steep angled secondary and intersecondary veins. Bar = 5 mm.

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Figure 27. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Crassidenticulum landisae Wang sp. nov. 1. UF15709-23280. Specimen with middle and basal portion observed showing pinnate primary venation. 2. Enlargement of Figure 27, 1 to show craspedodromous secondary venation, composite intersecondary veins, and teeth. Bar = 5 mm. 3. UF15709-23280Â’. Counterpart of Figure 27, 1, image is in a smaller scale compared with Figure 27, 1. 4. Enlargement of Figure 27, 3 to show teeth on margin. Bar = 5 mm. 5. UF15709-16549. Specimen showing obtuse apex. 6. Enlargement of Figure 27, 5 to show percurrent tertiary veins. Bar = 5 mm. 7. UF15709-24063Â’. Specimen with petiole observed. 8. Enlargement of Figure 27, 7 to show quaternary and quinternary veins. Bar = 5 mm. 9. UF15709-24043. Specimen showing obvate shape, obtuse apex, and pinnate primary venation.

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Figure 28. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Crassidenticulum landisae Wang sp. nov. 1. UF15709-16541. Specimen showing acute apex. 2. Enlargement of Figure 28, 1 (upper left portion) to show craspedodromous venation and straight basal side of teeth. Bar = 5 mm. 3. UF15709-24070. Specimen showing pinnate primary venation. 4. Enlargement of Figure 28, 3 (lower left middle portion of lamina) to show convex basal side of teeth. Bar = 5 mm. 5. Enlargement of Figure 28, 3 (upper right portion of lamina) to show teeth. Bar = 5 mm.

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Figure 29. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Yangia glandifolium Wang sp. nov. 1. UF15709-4754. Lower middle portion of lamina observed showing massive primary vein and possibly decurrent base. 2. Enlargement of Figure 29, 1 (area indicated by the lower arrow on the left in Figure 29, 1) to show thin secondary and intersecondary veins, and glands on leaf lamina. Bar = 5 mm. 3. Enlargement of Figure 29, 1 (are indicated by upper arrow on the left) to show marginal venation and teeth on leaf margin. Bar = 5 mm. 4. Enlargement of Figure 29, 1 (area indicated by the arrow on the right) to show teeth. Bar = 5 mm. Glandilunatus minnesotense Wang sp. nov. 5. UF 15709-11107. Enlargement of Figure 15, 7 to show venation and teeth on leaf margin. Note the cresulent teeth on leaf margin (indicated by arrow).

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Figure 30. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Trochodendroides cf. T. rhomboideus (Lesquereux) Berry 1922 1. UF15709-11860. Leaf with acuminate apex and suborbiculate shape. 2. Enlargement of upper left portion of lamina in Figure 30, 1 to show acuminate tooth apex. Bar = 5 mm. 3. UF15709-11897. An immature leaf with acrodromous primary venation and slender petiole. 4. UF15709-11897. A possible variation of leaf shape. Note the thin petiole. Dicotylophyllum huangia Wang sp. nov. 5. UF15709-16845. Leaf with ovate shape. 6. Figure 30, 5 enlarged to show semicraspedodromous secondary venation. Bar = 5 mm. Yangia glandifolium Wang sp. nov. 7. UF15709-31012. Leaf with insect galls. 8. Enlargement of Figure 30, 7 (middle portion of lamina) to see secondary venation and insect galls. Note numerous thin secondary veins and intersecondary veins diverging from primary vein at very large angles (almost perpendicular to primary vein). Bar = 5 mm.

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Figure 31. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Pabiania groenlandica (Heer) Wang comb. nov. 1. UF15706-24414. General view of leaf shape. Note slightly winged petiole. 2. UF15706-30154. Specimen with a complete petiole observed. Note long petiole and ocrea-like structure at the base. 3. Enlargement of Figure 31, 2 to show ocrea-like structure. Bar = 3 mm. 4. UF15706-14823. General leaf shape. Note basal actinodromous primary venation, basal secondary veins, and thin “winged” lamina structure on the petiole. 5. UF15706-24464. General leaf shape. Note typical rounded apex. 6. Enlargement of Figure 31, 5 to show straight primary vein and two series of loops in the excostal region. Bar = 2 mm. 7. UF15706-24423. Specimen showing suprabasal actinodromous primary venation. Note two pairs of basal secondary veins and sinus bracing by secondary veins (indicated by arrow) originated from medial and lateral primary veins.

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Figure 32. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Jaramillophyllum celatus (Lesquereux) Wang comb. nov. 1. UF15706-24491. Fragment a leaf. Note strong multistranded primary vein and decurrent lamina tissue on the petiole. Rogersia potteri Wang sp. nov. 2. UF15706-7529. Specimen showing leaf shape. 3. Enlargement of Figure 32, 2 to show secondary venation. Bar = 5 mm.

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Figure 33. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Pabiania variloba Upchurch and Dilcher 1990 1. UF15706-14832. Specimen showing typical leaf shape. Note suprabasal actinodromous primary venation, sinus bracing, and secondary vein pattern. 2. UF15706-24587. Unlobed leaf with suprabasal venation. 3. UF15706-14812. Unlobed leaf with slightly suprabasal actinodromous venation. 4. UF15706-24653. Another unlobed variation of leaf shape. Pabiania cf. P. groenlandica (Heer) Wang comb. nov. 5. UF15706-24565. A large leaf. Note recurved lateral primary veins and numerous insect galls. Pabiania variloba Upchurch and Dilcher 1990 6. UF15706-24483. A leaf attached to stem with a possibly axillary infructescence. 7. Enlargement of Figure 33, 6 to show dispersed fruits. Bar = 2 mm.

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Figure 34. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Crassidenticulum variloba Wang sp. nov. 1. UF15706-24684. Five lobed leaf. Note decurrent lamina tissue on sinus. Dicotylophyllum leptovena Wang sp. nov. 2. UF15706-24734. Enlargement of Figure 48, 8 (upper left portion of leaf lamina) to show venation. Note strong multistranded primary vein and thin secondary veins. Bar = 3mm. Credneria cyclophylla (Heer) Wang comb. nov. 3. UF15706-14821. Leaf showing craspedodromous venation. Note all secondary veins and their exmedial branches terminating on leaf margin, resulting in a wavy appearance of leaf margin. 4. UF15706-24783. Leaf showing craspedodromous venation. 5. UF15706-24780. Fragment of leaf. Note percurrent tertiary vein. Meiophyllum kowalskiae Wang sp. nov. 6. UF15706-24460Â’. Small five lobed leaf. Note thin secondary veins.

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Figure 35. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Rogersia kansense Wang sp. nov. 1. UF15706-3063. A reproductive shoot born in the axis of a leaf. 2. Enlargement of Figure 35, 1 to show infructescence. Bar = 2 mm. 3. Enlargement of Figure 35, 1 to show venation pattern. Note secondary veins originating from primary vein at very acute angles. Bar = 2 mm. 4. UF15706-24801. General leaf shape. Sapindopsis beekeria Wang sp. nov. 5. UF15706-24568. General leaf shape. Note straight secondary veins. Rogersia kansense Wang sp. nov. 6. UF15706-24798. General leaf shape. Note thin secondary veins forming intramarginal veins. Wolfiophyllum pfaffiana (Heer) Wang comb. nov. 7. UF15706-24620. General leaf shape. Note short petiole. Rogersia kansense Wang sp. nov. 8. UF15706-24591. Ultimate leaf shoot with alternate attached leaves.

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Figure 36. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Crassidenticulum variloba Wang sp. nov. 1. UF15706-24679. A trilobed leaf. Note thin, long petiole. Crassidenticulum trilobus Wang sp. nov. 2. UF15706-24677Â’. A trilobed leaf. Note strong multistranded primary vein, thin and long petiole. Sapindopsis retallackii Wang sp. nov. 3. UF15706-3153. Fragment of leaf. Note entire margin. 4. Enlargement of Figure 36, 3 to show numerous thin secondary and intersecondary veins. Bar = 2 mm. Crassidenticulum decurrens Upchurch and Dilcher 1990 5. UF15706-24648. Fragment of leaf. Note fine teeth on margin. 6. UF15706-24685. Leaf with basal and middle portion observed. Note petiole at base and fine teeth.

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Figure 37. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Meiophyllum expansolobum (Upchurch and Dilcher) Wang comb. nov. 1. UF15706-14827. Leaf with oblanceolate lobes. 2. UF15706-14826. Leaf with inner lateral lobe tending to lobe one more time. 3. UF15706-14825Â’. Leaf with irregular shape of lateral lobes. Note structurally reinforced margin on sinus, thickened lamina extension on thin and long petiole. 4. UF15706-24788. Deeply lobed leaf. Note apically curved outer lateral lobes. 5. UF15706-24461. Enlargement of Figure 37, 6 to show distorted leaf with wellpreserved secondary venation. Bar = 2 mm. 6. UF15706-24461. Distorted leaf. Meiophyllum kowalskiae Wang sp. nov. 7. UF15706-14824. Leaf with two lobes observed. 8. Enlargement of Figure 37, 7 to show venation pattern. Note thin primary and secondary vein, semicraspedodromous venation, and venation pattern of tooth. Bar = 2 mm.

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Figure 38. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Meiophyllum expansolobum (Upchurch and Dilcher) Wang comb. nov. 1. UF15706-31448. Leaf with irregular shaped lobes. 2. Enlargement of Figure 38, 1 (indicated by arrow) to show tooth type. Bar = 2 mm. 3. UF15706-30158. Specimen showing complete leaf. Note long petiole with swollen base and extension of leaf lamina on petiole. 4. Enlargement of Figure 38, 3 to show swollen petiole base. Bar = 5 mm. 5. UF15706-14828. Leaf with right outer lobe (indicated by arrow) tending to lobe one more time. 6. Enlargement of Figure 38, 5 (indicated by left arrow) to show sinus bracing. Note two secondary veins from primary veins joining and then running along the sinus. Bar = 5 mm. 7. Enlargement of counterpart specimen of Figure 38, 5 (area indicated by right arrow) to show venation pattern. Bar = 2 mm. 8. Enlargement of Figure 38, 5 (near left arrow) to show venation pattern. Note well-defined intercostal region, intersecondary veins, and a series of loops of tertiary order in the excostal region. Bar = 2 mm.

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Figure 39. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Sapindopsis bagleyae Wang sp. nov. 1. UF15706-14830. Leaf with four leaflets. No te two ultimate leaflets appearing to be bilobed, two oppositely arranged lateral leaflets, and stipules at the base. 2. UF15706-24481. Middle portion of a leaflet. 3. Enlargement of Figure 39, 2 to eucamptodromous venation. Bar = 2 mm. 4. UF15706-24758. Distal portion of a leaflet to show marginal venation. Bar = 4 mm. 5. UF15706-24747. Leaf with one elliptic ultimate leaflet and two opposite lateral leaflets. 6. UF15706-24681. Leaf with one ultimate leaflet and two oppositely arranged leaflets that are lacking petiolules. 7. UF15706-24683Â’. Leaf with two sub-oppositely arrange leaflets with petiolules.

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Figure 40. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Sapindopsis bagleyae Wang sp. nov. 1. UF15706-14831. Leaf with three leaflets. Note acuminate apex on left leaflet. 2. Enlargement of Figure 40, 1 to show eucamptodromous secondary venation. Bar = 2 mm. 3. Enlargement of Figure 39, 1 to show stipule. Note venation pattern. Bar = 2 mm. 4. Enlargement of Figure 39, 1 to show eucamptodromous secondary venation. Note composite intersecondary veins, tertiary veins tending to be percurrent and almost perpendicular to primary vein. Bar = 2 mm. 5. UF15706-24675. Leaf with “bilobed” appearance. Note “bilobed” ultimate two leaflets and deeply lobed leaflet apex.

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Figure 41. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Sapindopsis bagleyae Wang sp. nov. 1. UF15706-24719. Leaf with two opposite latera l leaflets, one ultimate leaflet with long and thin petiolule, and stipule at the base of petiole. 2. UF15706-31455. Enlargement of Figure 41, 3 to show stipule. Bar = 2 mm. 3. UF15706-31455. Leaf with four leaflets. 4. UF15706-24711. Leaf with six sessile leaflets. Note eucamptodromous secondary venation and strong secondary veins. 5. UF15706-24670. Leaf with four leaflets. Note bilobed ultimate leaflets, sessile lateral leaflet, and strong secondary veins. 6. UF15706-14814. An elliptic leaflet with acuminate apex. 7. UF15706-4812. Leaf with narrow oblong leaflets. Note structurally reinforced lamina margin.

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Figure 42. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Sapindopsis beekeria Wang sp. nov. 1. UF15706-14813. General leaf shape. Bar = 5 mm. Anisodromum wolfei Upchurch and Dilcher 1990 2. UF15706-24566. General leaf shape. 3. Enlargement of Figure 42, 2 to show venation pattern. Note percurrent tertiary veins oriented almost perpendicular to primary vein. Bar = 2 mm. Sapindopsis beekeria Wang sp. nov. 4. UF15706-14922. Two leaflets showing opposite arrangement. Anisodromum wolfei Upchurch and Dilcher 1990 5. UF15706-14818. General leaf shape. Note long petiole. 6. Enlargement of Figure 42, 5 to show venation pattern. Note percurrent tertiary veins oriented perpendicular to primary vein. Bar = 3 mm.

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Figure 43. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Anisodromum upchurchii Wang sp. nov. 1. UF15706-24576. Middle portion of lamina. Note strong primary and secondary veins. 2. Enlargement of Figure 43, 1 to show higher order venation pattern. Bar = 3 mm. Wingia anisos Wang sp. nov. 3. UF15706-24635. General leaf shape. Note the uneven spacing of secondary veins. 4. UF15706-24633. General leaf shape. Anisodromum upchurchii Wang sp. nov. 5. UF15706-24636. General leaf shape. Jarzenia kanbrasota Wang sp. nov. 6. UF15706-24492. Basal portion of leaf lamina. 7. UF15706-3171. General leaf shape.

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Figure 44. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Longstrethia aspera (Lesquereux) Wang comb. nov. 1. UF15706-24578. Middle portion of lamina. 2. Enlargement of Figure 44, 1 (left middle portion of lamina) to show fine venation. Bar = 2 mm. Wolfiophyllum pfaffiana (Heer) Wang comb. nov. 3. UF15706-14815. Basal and middle portion of lamina. Note strong primary vein, entire margin, and insect damage on left middle portion of lamina. 4. Enlargement of Figure 44, 3 to show eucamptodromous venation. Note intersecondary veins. Bar = 3 mm. Longstrethia aspera (Lesquereux) Wang comb. nov. 5. UF15706-24650. Basal and middle portion of lamina. Note craspedodromous secondary venation and toothed margin. Skogia leptoselis Wang sp. nov. 6. UF15706-24573. Fragment of lamina. 7. Enlargement of Figure 44, 6 to show secondary and intersecondary veins. Note multistranded primary vein. Bar = 3 mm.

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Figure 45. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Nelumbites fluitus Wang sp. nov. 1. UF15706-8263. General leaf shape. Note the floating structure attached on the petiole. Bar = 5 mm. 2. UF15706-8263Â’. Counterpart of Figure 45, 1. Bar = 5 mm. 3. UF15706-8268. General leaf shape. Note medial primary vein, two lateral primary veins on each side, and auriculate base. All lateral veins and exmedial branches of outer lateral veins are apically curved. Bar = 5 mm. 4. UF15706-24088. General leaf shape. Note auriculate base and apically curved primary veins. Bar = 5 mm. 5. UF15706-24120. Specimen showing auriculate base and floating structure on basal left side. Bar = 5 mm. 6. UF15706-24094. Specimen showing fine venation. Note degrading primary vein, reticulate higher order veins, and numerous dots, which are probably resulted from air lacunae. Bar = 3 mm. 7. UF15706-24637. Leaf with a floating structure attached. Bar = 5 mm.

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Figure 46. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Nelumbites fluitus Wang sp. nov. 1. UF15706-24086. Leaf with a floating structure attached. Bar = 5 mm. Nelumbites crassinervum Wang sp. nov. 2. UF15706-3666. General leaf shape. Note thick primary veins degrading into higher order veins. The dark area where primary veins diverging indicates a possible floating structure attached on petiole. Nelumbites fluitus Wang sp. nov. 3. UF15706-8264. Leaf with a floating structure attached. Bar = 5 mm. 4. UF15706-3116. General leaf shape. Bar = 5 mm. A rhizome-like structure associated with Nelumbites . 5. UF15706-3075Â’. Bar = 5 mm. Nelumbites farleyi Wang sp. nov. 6. UF15706-14806. General leaf shape. Note entire margin, peltate-central base, medial primary vein, and five lateral primary veins on each side. 7. UF15706-24103. A smaller leaf. Note peltate-central base, a medial primary vein, and 5 lateral primary veins.

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Figure 47. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Nelumbites crassinervum Wang sp. nov. 1. UF15706-3666Â’. Counterpart of Figure 46, 2. Possible floating structure of Nelumbites. 2. UF15706-24116. A floating structure associated with Nelumbites . Bar = 5 mm. Nelumbites crassinervum Wang sp. nov. 3. UF15706-24108. Half leaf lamina. Note toothed margin. 4. Enlargement of Figure 47, 3 to show venation pattern of tooth. Note shallow sinus and three veins entering one tooth. Bar = 2 mm. 5. UF15706-24648. Leaf with possible insect damage. 6. UF15706-14822. Fragment of leaf to show tooth pattern. Note relatively deep sinus, and three veins entering one tooth. Bar = 2 mm.

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Figure 48. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Citrophyllum alteruans (Heer) Wang comb. nov. 1. UF15706-24332. General leaf shape. 2. UF15706-24584. Elliptic leaf. 3. Enlargement of Figure 48, 2 (left basal portion of lamina) to show thin secondary and intersecondary veins. Note insect galls near primary vein. Bar = 2 mm. 4. UF15706-24645. Inflated petiole base and lamina tissue on both sides. Bar = 5 mm. 5. UF15706-24995. Ovate leaf shape. Note demarcation between lamina wing and leaf lamina, and inflated petiole base. Bar = 5 mm. 6. Enlargement of Figure 48, 5 to show winged petiole. Bar = 2 mm. 7. UF15706-24646. General leaf shape. Note demarcation between lamina wing and leaf base. Dicotylophyllum leptovena Wang sp. nov. 8. UF15706-24734. Middle and basal portion of leaf. Note fine venation.

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Figure 49. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Setterholmia callii Wang sp. nov. 1. UF18267-16580Â’. General view of leaf showing obvate shape. Setterholmia rotundifolia (Lesquereux) Wang comb. nov. 2. UF18267-16581. Middle and distal portion of leaf lamina. Note intersecondary veins, exmedial branches of secondary veins, and looping pattern near the margin. 3. UF18267-16581Â’. Counterpart of Figure 49, 2. 4. UF18267-16582. Middle portion of leaf lamina. 5. UF18267-16583. General view of leaf showing obvate shape. 6. UF18267-16586. Part of leaf lamina showing secondary and tertiary venation. 7. UF18267-24820. Half of the lamina showing secondary venation. Setterholmia callii Wang sp. nov. 8. UF18267-20332Â’. Basal portion of the leaf lamina showing short stout petiole. Setterholmia rotundifolia (Lesquereux) Wang comb. nov. 9. UF18267-20141. Basal portion of leaf showing stout short petiole. 10. Enlargement of Figure 49, 9 to show looping pattern at the base. Bar = 3 mm.

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Figure 50. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Jarzenia kanbrasota Wang sp. nov. 1. UF18267-24824. Middle-upper portion of the leaf showing entire margin. 2. Enlargement of Figure 50, 1 to show secondary and higher order venation patterns. Bar = 2 mm. 3. UF18267-16599. Basal portion of leaf to show petiole and revolute leaf lamina. 4. UF18267-16599Â’. Counterpart of Figure 50, 4. 5. UF18267-24837I. Showing the obvate leaf shape and multistranded primary vein. 6. UF18267-26144. Showing cuneate leaf base and secondary venation. Rogersia kansense Wang sp. nov. 7. UF18267-24845. Middle portion of the leaf with well preserved venation. 8. Enlargement of Figure 50, 7 to show multistranded secondary vein. Bar = 2 mm. Jarzenia kanbrasota Wang sp. nov. 9. UF18267-16571. Distal portion of leaf showing thick secondary venation. 10. UF18267-26132. Basal portion of leaf showing the petiole. Liriophyllum siemia Wang sp. nov. 11. UF18267-26118. Specimen showing leaf shape and emarginate apex.

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Figure 51. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Trochodendroides rhomboideus (Lesquereux) Berry 1922 1. UF18267-16592. Immature leaves. Note well-developed three primary veins and teeth. Bar = 5 mm. 2. UF18267-21217Â’. Basal portion of leaf. Note three primary veins and thin petiole. 3. UF18267-16602. Leaf showing acrodromous primary venation and attenuate apex. 4. UF18267-16596. General view of leaf shape. Note acrodromous primary venation, exmedial (lower) branches of lateral primary veins. 5. Enlargement of Figure 51, 4 to show fine venation. Note random reticulate high order venation. Bar = 2 mm. 6. Enlargement of Figure 51, 4 to show venation pattern on the tooth. Note occasional compound tooth. Bar = 2 mm. 7. UF18267-16595. Showing acrodromous venation. Dicotylophyllum leptovena Wang sp. nov. 8. UF18267-21214. Basal portion of leaf lamina. 9. UF18267-21224Â’. Counterpart of Figure 51, 8. Trochodendroides rhomboideus (Lesquereux) Berry 1922 10. UF18267-16607. Basal portion of leaf lamina. Note three basal primary veins with exmedial branches. Rogersia kansense Wang sp. nov. 11. UF18267-21194IÂ’. Middle portion of leaf lamina. 12. UF18267-24856. Basal portion of leaf lamina with asymmetrical base. 13. UF18267-24846. Distal portion of leaf lamina with acuminate apex. Dicotylophyllum leptovena Wang sp. nov. 14. Enlargement of middle portion of Figure 51, 9 to show thin secondary and tertiary veins. Bar = 2 mm. Rogersia kansense Wang sp. nov. 15. UF18267-16576Â’. Basal portion of leaf with short petiole. 16. Enlargement of Figure 51, 11 to show multistranded primary vein and brochidodromous secondary venation. Bar = 2 mm.

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Figure 52. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Manchesterii macrophylla (Lesquereux) Wang comb. nov. 1. UF18267-16600. Middle portion of leaf. 2. Enlargement of Figure 52, 1 (upper right portion of lamina) to show structurally reinforced margin. Bar = 2 mm. Dicotylophyllum carlsonia Wang sp. nov. 3. UF18267-16603. General leaf shape. Note fine teeth on apical portion of lamina. Manchesterii macrophylla (Lesquereux) Wang comb. nov. 4. UF18844-32485. Middle and apical por tion of leaf. Note festooned brochidodromous venation and attenuate apex. 5. Enlargement of Figure 52, 4 (middle portion of lower right lamina) to show fine venation. Note intersecondary veins and reticulate higher order veins. Bar = 3 mm. 6. Enlargement of Figure 52, 4 (upper left portion of lamina) to show fine venation. Note inter-intersecondary veins. Bar = 2 mm.

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Figure 53. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Jarzenia reticulatus Wang sp. nov. 1. UF18267-16614. Middle portion of lamina. 2. UF18267-16614Â’. Counterpart of Figure 53, 1. 3. Enlargement of Figure 53, 2 to show secondary and tertiary venation. Bar = 3 mm. Pandemophyllum attenuatum Upchurch and Dilcher 1990 4. UF18267-16570. Specimen showing elliptic shape and attenuate apex. 5. UF18267-26119. Specimen showing short petiole and longer attenuate apex. 6. Enlargement of Figure 53, 5 to show venation pattern near the attenuate apex. Bar = 3 mm. 7. UF18267-24859Â’. Showing obvate shape and short attenuate apex. 8. UF18267-26120. Showing typical ovate shape. 9. UF18844-32488. Showing attenuate apex with medium length. 10. UF18844-32487. General view of leaf shape. 11. UF18267-16569. Showing attenuate apex. Pandemophyllum gracifolia Wang sp. nov. 12. UF18267-26122. Specimen showing obvate leaf shape. Bar = 5 mm. 13. UF18267-16611. Middle portion of leaf showing secondary venation. Bar = 5 mm. 14. UF18267-26121. Specimen showing obvate leaf shape and thin petiole. Bar = 5 mm.

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Figure 54. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Glandilunatus minnesotense Wang sp. nov. 1. UF18267-16585. Basal portion of leaf showing long petiole. 2. Enlargement of Figure 54, 1 to show glandular teeth and vein pattern on the tooth. Bar = 2 mm. 3. UF18267-24841. Half of the leaf lamina observed. Note general leaf shape, exmedial branches of basal secondary veins, and composite teeth. 4. UF18267-24771. Venation pattern near the base of leaf lamina. 5. UF18267-26151. Specimen showing general leaf shape. Pandemophyllum kvacekii Upchurch and Dilcher 1990 6. UF18267-26136. Specimen showing general leaf shape. 7. UF18267-16570II. Specimen showing obvate leaf shape. 8. UF18267-26142. Leaf with well-preserved cuticle. 9. UF18267-26138. Middle portion of leaf. Dicotylophyllum tulipifera (Heer) Wang comb. nov. 10. UF18267-16588Â’. Leaf base with petiole. Bar = 5 mm. 11. UF 18267-16588. Counterpart of Figure 54, 10. Bar = 5 mm. 12. Enlargement Figure 54, 11 to show distinct secondary veins and thin higher order veins. Bar = 2 mm.

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Figure 55. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Credneria cyclophylla (Heer) Wang comb. nov. 1. UF18267-26128. General leaf shape. Note exmedial branches of basal secondary veins and tertiary venation pattern. 2. UF18267-26134. Specimen showing general leaf shape. Note inflated petiole base indicated by arrow. 3. UF18267-16597. Specimen showing orbiculate leaf shape. 4. UF18267-26154. Specimen showing orbiculate leaf shape. 5. UF18267-16601. Basal portion of leaf. Note slightly suprabasal secondary veins. 6. UF18267-24819Â’. Fragment of leaf lamina. 7. Enlargement of Figure 55, 6 to show venation pattern on the tooth and possible hydathodes. Bar = 2 mm.

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Figure 56. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Crepetia minudentis Wang sp. nov. 1. UF18267-26150. General leaf shape. 2. Enlargement of Figure 56, 1 to show venation pattern on the teeth. Note insect damage on the margin. Bar = 3 mm. 3. Enlargement of Figure 56, 1 to show fine venation on the sinus. Bar =3 mm. 4. Enlargement of Figure 56, 1 to show glandular teeth. Bar = 3 mm. 5. UF18267-16590Â’. Basal portion of leaf lamina. Note truncate base and slender petiole. 6. UF18267-16590. Counterpart of Figure 56, 5. 7. Enlargement of the upper right portion of leaf lamina in Figure 56, 6 to show glandular teeth and possible hydathodes. Bar = 2 mm. Wolfiophyllum pfaffiana Wang sp. nov. 8. UF18267-24857Â’. Apical portion of leaf shoring acute apex and eucamptodromous secondary venation. 9. UF18267-16606. General shape and asymmetrical lamina base. 10. UF18267-24838. Middle portion of lamina showing secondary venation. 11. UF18267-16568Â’. Basal portion of lamina showing eucamptodromous secondary venation. 12. Enlargement of Figure 56, 11 to show secondary venation. Bar = 2 mm.

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Figure 57. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Dicotylophyllum coughlantia Wang sp. nov. 1. UF18267-20249. Fragment of leaf lamina. 2. Enlargement of upper left leaf lamina in Figure 57, 1 to show secondary and tertiary veins. Bar = 2 mm. 3. UF18267-20249Â’. Counterpart of Figure 57, 1. 4. Enlargement of Figure 57, 3 to show venation on the sinus. Bar = 2 mm. 5. UF18267-24773Â’. Specimen showing petiole. 6. UF18267-24773. Counterpart of Figure 57, 5. 7. Enlargement of upper left leaf lamina in Figure 57, 5 to show venation on the sinus. Bar = 2 mm. 8. Enlargement of basal leaf lamina in Figure 57, 7 to show venation. Note thin tertiary veins originated from primary vein. Bar =3 mm.

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Figure 58. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Liriophyllum siemia Wang sp. nov. 1. UF18267-26152. General leaf shape. 2. Enlargement of Figure 58, 1 to show secondary, intersecondary, and tertiary veins. Bar = 3 mm. Wolfiophyllum pfaffiana Wang sp. nov. 3. UF18267-16563. General shape and round apex. 4. UF18267-16572. General shape. Showing multistranded primary vein and short petiole. 5. UF18267-24869. Basal portion of leaf showing short petiole. Liriophyllum siemia Wang sp. nov. 6. UF18267-26121. Middle and distal portion of leaf showing indented apex. 7. Enlargement of Figure 58, 6 to show venation. Bar = 3 mm. Wolfiophyllum pfaffiana Wang sp. nov. 8. UF18267-24869. Basal portion of leaflet showing short petiole. 9. UF18267-21218. Apical portion of lamina showing eucamptodromous secondary venation. Liriophyllum siemia Wang sp. nov. 10. UF18267-26256. General leaf shape. 11. Enlargement of Figure 58, 10 to show secondary and tertiary venation. Bar = 3 mm.

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Figure 59. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Crassidenticulum cracendentis Wang sp. nov. 1. UF18267-16591. Middle portion of the leaf lamina. 2. Enlargement of Figure 59, 1 (upper left portion of leaf) to show teeth type and possibly deciduous glandular teeth. Bar = 2 mm. 3. UF18267-16591Â’. Counterpart of Figure 59, 1 enlarged to show teeth and secondary venation. Bar = 2 mm. 4. UF18267-16598. Middle portion of leaf. Note fragmented leaf lamina. 5. Enlargement of Figure 59, 4 to show venation and teeth (upper right portion of leaf). Bar = 2 mm. Dicotylophyllum crasseprimus Wang sp. nov. 6. UF1826716604. Middle portion of leaf lamina. Note strong multistranded primary vein. 7. Enlargement of Figure 59, 6 to show venation pattern near the margin. Note marginal fimbrial vein near the margin. Bar = 3 mm.

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Figure 60. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Densinervum kaulii Upchurch and Dilcher 1990 1. UF18267-26153b. Showing elliptic leaf shape. Wolfiophyllum pfaffiana Wang sp. nov. 2. UF18267-21200. Middle and basal portion of leaf. 3. Enlargement of Figure 60, 2 to show multistranded primary vein and secondary venation. Bar = 2 mm. Rogersia kansense Wang sp. nov. 4. UF18267-20671. Shoot to show leaf attachment. Densinervum kaulii Upchurch and Dilcher 1990 5. UF 18267-16610. Basal portion of leaf lamina. Note the thin petiole. 6. UF 18267-26153a. Showing orbicular leaf shape. Note the indented apex. Setterholmia deleta (Lesquereux) Wang comb. nov. 7. UF 18267-16564. Specimen showing general leaf shape. 8. Enlargement of Figure 60, 7 to show venation pattern. Note irregularly spaced secondary veins. Bar = 1 mm. Densinervum kaulii Upchurch and Dilcher 1990 9. UF 18267-16562. Showing an elliptic leaf shape. 10. Enlargement of the upper left portion of lamina in Figure 60, 9 to show venation pattern near the margin. Bar = 2 mm.

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Figure 61. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Manchesterii macrophylla (Lesquereux) Wang comb. nov. 1. UF18038-31702Â’. Leaf showing decurrent base. 2. UF18038-32198. Middle portion of leaf. Note the stout primary vein, the angle of divergence of secondary veins, abundance of secondary and intersecondary veins. 3. UF18038-31705Â’. Specimen showing apical portion of leaf. 4. UF18038-31703. Specimen showing middle portion of leaf. 5. Enlargement of Figure 61, 4 (area indicated by arrow) to show secondary and higher order venation. Note the stout primary vein (1 ) and three series of exmedial loops near the margin. Bar = 2 mm. 6. UF18038-31719. Basal portion of leaf with short, stout petiole observed (indicated by arrow).

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Figure 62. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Sungia delicatus Wang sp. nov. 1. UF18038-31724. Specimen showing trilobed leaf. 2. UF18038-31724Â’. Counterpart of Figure 62, 1. 3. Enlargement of partial leaf lamina of Figure 62, 2 (indicated by arrow) to show primary vein, secondary and intersecondary veins. Note intramarginal vein. Bar = 2mm. 4. Enlargement of basal portion of leaf lamina of Figure 62, 2 to show pattern below sinuses. Bar = 2mm. 5. Enlargement of partial leaf lamina of Figure 62, 1 (indicated by arrow) to show fine venation. Bar = 2mm.

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Figure 63. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Sapindopsis retallackii Wang sp. nov. 1. UF18038-31730. Specimen with basal portion of three leaflets observed. Note pronounced revolute lamina. 2. Enlargement of Figure 63, 1 to show secondary venation. Bar = 2 mm. Jarzenia kanbrasota (Heer) Wang comb. nov. 3. UF18038-31751. Specimen showing general elliptic shape. Rogersia kansense Wang sp. nov. 4. UF18038-31780. Basal portion of leaf lamina to shoe petiole. Jarzenia kanbrasota (Heer) Wang comb. nov. 5. UF18038-31749. Specimen showing elliptic shape and secondary venation. 6. UF18038-31738. Specimen showing short petiole and round apex. 7. UF18038-31745. Basal portion of a leaf. 8. Enlargement of Figure 63, 7 to shoe secondary venation. Bar = 3 mm.

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Figure 64. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Meiophyllum expansolobum (Upchurch and Dilcher) Wang comb. nov. 1. UF18038-31736. Specimen showing basal portion of lamina. 2. UF18038-31735. Basal portion of leaf to show petiole base. Rogersia kansense Wang sp. nov. 3. UF18038-31762. Middle portion of a leaf to show venation pattern. Credneria cf. Credneria cyclophylla (Heer) Wang comb. nov. 4. UF18038-31734. Overall leaf shape with insect galls. 5. Enlargement of Figure 64, 4 to show fine venation. Bar = 5 mm. Dicotylophyllum denticulatus Wang sp. nov. 6. UF18038-31731. Middle portion of leaf to show venation pattern. Note fine teeth on margin (indicated by arrow). Trochodendroides rhomboideus (Lesquereux) Berry 1922 7. UF18038-31733. Basal portion of leaf to s how actinodromous venation. Note the thin petiole. Quercophyllum tenuinerve Fontaine 1889 8. UF18038-31732. Middle and apical portion of leaf to show tooth type and venation pattern. Bar = 5 mm.

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Figure 65. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Rogersia kansense Wang sp. nov. 1. UF18038-31766Â’. Overall view of leaf showing the linear leaf shape. 2. Enlargement of left middle portion of lamina of Figure 65, 1 to show primary vein and thin secondary veins. Bar = 2 mm. 3. UF18038-31772. General view of linear leaf shape with well preserved cuticle. 4. UF18038-31768. Specimen showing short petiole. Rogersia parlatorii Fontaine 1889 5. UF18038-31836. General view of leaf shape and short petiole. 6. UF18038-31759. Basal portion of leaf showing venation. 7. UF18038-31760. Middle portion of leaf showing fine venation and well preserved cuticle. 8. UF18038-31833. Basal portion of leaf to show petiole. 9. UF18038-31763. Middle portion of leaf to show well-preserved cuticle. Rogersia cf. R. parlatorii Fontaine 1889 10. UF18038-31739. Middle portion of leaf showi ng the nature of the fine venation. 11. Enlargement of left middle portion of Figure 65, 10 to show secondary and tertiary venation pattern. Bar = 2 mm.

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Figure 66. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Sapindopsis retallackii Wang sp. nov. 1. UF18047-31563. Specimen showing recurved primary veins of lateral leaflets. 2. UF18047-31566. Middle portion of leaflet lamina showing secondary venation and entire margin. 3. UF18047-31567. Specimen showing acute apex and entire margin. 4. UF18047-31564. Leaflet showing secondary venation and attenuate apex. 5. UF18047-31571. Compound leaf with one sessile lateral leaflet. 6. Enlargement of Figure 66, 5 to show fine venation pattern. Bar = 2 mm. 7. UF18047-31569. Leaf with three leaflets. Note straight primary veins and abaxially curved laminae. 8. UF18047-31585. Leaf with three leaflets. Note long petiole of ultimate leaflet.

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Figure 67. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Sapindopsis retallackii Wang sp. nov. 1. Enlargement of Figure 66, 8 to show venation pattern. Bar = 2 mm. 2. UF18047-31583. Compound leaf with three leaflets at ultimate end and one leaflet attached on the right side of petiole (leaf indicated by right arrow). Leaf on the left has four ultimate leaflets (indicated by left arrow). Note all leaflets curved abaxially. 3. Enlargement of Figure 67, 2 to show venation. The wavy appearance of leaf margin is just an artifact of preservation. Bar = 2 mm. 4. UF18047-31572. Fragment of middle portion of a leaflet, about 15cm long (estimated length) by 4cm wide, showing strong secondary vein loops and intersecondary veins. 5. Enlargement of Figure 66, 4 (left middle portion of lamina) to show details of venation. Bar = 2 mm.

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Figure 68. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Aspidiophyllum obtusum (Lesquereux) Wang comb. nov. 1. UF18047-14977. Specimen showing general leaf shape. 2. Enlargement of Figure 68, 1 (indicated by arrow) to predominately craspedodromous venation. Bar = 5 mm. 3. UF18047-31600. Suprabasal primary venation. 4. UF18047-31624. General view of leaf shape and suprabasal primary venation. 5. UF18047-31604. Specimen showing predom inately brochidodromous venation. 6. UF18047-14976. Specimen showing a mixture of craspedodromous and brochidodromous secondary venation. ? Menispermites sp. 7. UF18047-31693. Specimen showing pinnate primary venation with two pairs of basal secondary veins.

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Figure 69. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Eurylobum dentatum (Lesquereux) Schwarzwalder and Dilcher 1. UF18047-14978. Specimen showing a leaf with wavy margin. 2. Enlargement of Figure 69, 1 to show craspedodromous venation. Note one exmedial branch from each secondary vein tending to be brochidodromous. Bar = 3 mm. Platanoid infructescences. 3. UF18047-31668. An infructescence associated with platanoid leaves. Eurylobum dentatum (Lesquereux) Schwarzwalder and Dilcher 4. UF18047-31638. Specimen with peltate base. 5. Enlargement of Figure 69, 4 to show the peltate base and venation. Bar = 3 mm.

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Figure 70. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Eurylobum dentatum (Lesquereux) Schwarzwalder and Dilcher 1. UF18047-31626. Specimen showing deep lobes. 2. Enlargement of Figure 70, 1 to show one lobe and venation pattern. Note incomplete craspedodromous venation (with some brochidodromous tertiary veins) and inverted ‘V’ shaped tertiary veins below the sinus between primary and secondary veins. Bar = 5 mm. 3. UF18047-31625. Specimens showing rounded lobes apex. 4. Enlargement of Figure 70, 3 (indicated by arrow) to show craspedodromous venation in one lobe. Bar = 2 mm. Platanoid infructescences. 5. UF18047-31664. An incomplete infructescence with 7 fruiting heads. Note the small size of fruiting heads. 6. Enlargement of three heads (in the middle portion of Figure 70, 5) to show details of fruiting heads. Bar = 2 mm.

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Figure 71. Illustration of leaf megafossils from the Dakota Formation. All bars equal 1 cm unless otherwise indicated. Pabiania variloba Upchurch and Dilcher 1990 1. UF18047-31606. Specimen showing rhomboid shape. Aspidiophyllum obtusum (Lesquereux) Wang comb. nov. 2. UF18047-31603. Specimen showing long, incomplete petiole and auricular base. Pabiania variloba Upchurch and Dilcher 1990 3. UF18047-31589. Specimen showing actinodromous venation. Aspidiophyllum obtusum (Lesquereux) Wang comb. nov. 4. UF18047-31601. Specimen showing auricular base. 5. Enlargement of Figure 71, 4 to show auricular base, suprabasal primary veins, and basal secondary veins. Bar = 5 mm. Pabiania variloba Upchurch and Dilcher 1990 6. UF18047-31605. Specimen showing long petiole and actinodromous venation.

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Figure 72. Leaf megafossl localities of the Dakota Formation. BraunÂ’s Ranch, Kansas. Top-northeast coner of the clay pit. Bo ttom-southwest corner of the clay pit.

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Figure 73. Leaf megafossil localities of the Dakota Formation. Top-Hoisington III, Kansas. Bottom-Pleasant Dale, Nebraska.

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Figure 74. Leafmegafossil localities of the Dakota Formation. Top-Rose Creek I, Nebraska. Bottom-Courtland I, Minnesota.

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Figure 75. Specimens showing well preserved leaf megafossils without sorting. 1. Liriophyllum kansense Dilcher and Crane 1984. 2. Meiophyllum expansolobum Upchurch and Dilcher 1990 and Sapindopsis leaflets. Bars equal 1 cm.

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354 CHAPTER 4 PALEOCLIMATE IMPLICATIONS Background Study The mid-Cretaceous (Aptian-Albian-Cenomanian, about 120-90 million years before present) is a time period during the earth’s history for which there is frequently cited evidence for a generally warm and equitable climate, with atmospheric CO2 and O2 concentrations greater than those of present, and perhaps ice-free paleoclimate (Barron et al., 1981; Barron and Washington, 1982; Berner et al., 1983; Arthur and Dean, 1986; Berner, 1993, 1994; Fassell and Bralower, 1999). This is supported by both direct ad indirect geological evidence. Direct eviden ce includes biogeography of terrestrial plants (Parrish and Spicer, 1988) and nannofossils (Mutterlose, 1992), coral reefs which extended 5 to 15 poleward of their present habitat (Habicht, 1979), floral provinces which expanded as much as 15 poleward of their present location (Vakhrameev, 1964; Barnard, 1973; Vakhrameev, 1975; Vakhrameev and Hughes, 1991), other plant assemblages at high latitudes that indicated mild/warm temperatures (Smiley, 1967; Taylor, 1972; Krassilov, 1973, 1981), and breadfru it fossils which were found growing as far north as Greenland (55° N paleolatitude) (Nathorst, 1911). Indirect evidence includes stable isotopic evidence from marine record (Fassell and Bralower, 1999), increased ridge-crest and midplate volcanic activity (Schlanger et al., 1981; Larson, 1991), and enhanced atmospheric CO2 several times of present levels (Berner et al., 1983; Arthur and Dean, 1986; Berner, 1993, 1994).

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355 Albian sea-surface temperatures (SSTs) were warmer than those measured anywhere in the modern oceans (Norris and Wilson, 1998). Reconstruction of SSTs suggests that the Cretaceous greenhouse climate began in the late Albian rather than the late Cenomanian as suggested in previous climate reconstruction. Results based on oxygen isotope records ( 18O) of bottom-dwelling organisms indicate that Cretaceous intermediate-deep waters were about 15 C warmer than present (Emiliani, 1961; Savin, 1977). Oxygen isotope ( 18O) also suggests that midand high-latitude surface temperatures were warmer than those of the present (Barron, 1983). However, there are some problems associated with these measurements. For example, Emiliani (1961) and SavinÂ’s (1977) results seem incompatible with the presence of extensive high-latitude ice in the Cretaceous and other published records have not been properly examined to test for diagenetic effects. There are two major uncertainties associated with the Cretaceous warmth. One is the presence or absence of permanent ice, i.e., whether the warmth was year-round. Seasonally cold conditions are suggested by scattered evidence for ice-rafted deposits in both the Northern and Southern Hemispheres (Frakes and Francis, 1988), though no unequivocal tillites of Cretaceous age have been found (Hambrey and Harland, 1981). Paleobotanical evidence from the North Slope of Alaska (paleo-latitude 70 to 80 ) suggests that those fossil plants are deciduous, which is additional evidence for seasonality (Spicer and Parrish, 1986). Another uncertainty associated with the Cretaceus warmth is the question of lowlatitude sea surface temperatures (SSTs). Although isotopic data from foraminifera indicate that the mid-Cretaceous (late Albian to early Cenomanian) subtropical North

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356 Atlantic had sea surface temperatures (SSTs) between 30 and 31°C, warmer than average modern temperatures in modern tropical western Atlantic (Norris and Wilson, 1998), there is still not sufficient evidence of warm or warmer equatorial temperatures from lowlatitude. Some evidence indicates that low-latitude SSTs were significantly lower than present for much of the Cretaceous (Wilson et al., 1999). Paleoclimatic Implications from Angiosperm Leaf Megafossils Leaf Margin Analysis Mean Annual Temperature has been correlated with dicot leaf margin characteristics (Wolfe, 1979; Wilf, 1997). Ratio of entire-margined leaves to those with serrations (teeth) correlates directly with mean annual temperature (MAT). A preliminary physiognomic analysis of the leaf assemblage from the Courtland I locality (Dilcher and Nowak, personal communication) indicates that the mean annual temperature for this locality is about 22 C. Hydathodes Hydathodes are epidermal structures specialized for secretion, or for exudation, of water. Hydathodes can often be found at the end of vascular bundles of leaves. Vein ending hydathodes are also called active hydathodes and they are essentially modified teeth, with tightly packed epithem cells (chloroplanst free, more or less modified mesophyll cells) surrounded by a sheath (often with casparian strips) and one or more water pores (stomates that are usually permanently open); water passed through epithem cells and minerals may be re absorbed (mediated by transfer cells) before water is forced out through the pores(s). The process of secreting excess water is called guttation. Guttation has been observed in more than 330 genera of 115 plant families. For example, guttation has been observed to occur in Rosaceae , Scrophulariaceae, Ranunculaceae,

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357 Tropaeolacceae (Watson and Dallwitz, 2002), and the leaf tips of many grasses. When ground and atmosphere are saturated, and thus not much transpiration occurring, plants can excrete water and thus relieve excess pressure through hydathodes. Therefore, guttation is more frequent at night and most common in humid, tropical areas where higher soil temperatures favor root absorption and the moist atmosphere retards transpiration. Salt, sugar, and organic compounds that are dissolved in the guttation water crystallize after evaporation of the water at the site of outflow. Hydathodes are also present in desert plant leaves. For example, Martin and von Willert (2000) studied 46 of 48 species of Crassula collected from the Namib Desert in southern Africa. They proposed that although rainfall in the Namib Desert is infrequent, surface wetting of the leaves is a more common occurrence as a result of nighttime dew or fog deposition, hence species with hydathodes benefit directly from this source of moisture. Hydathodes are very common in many species from the Dakota Formation. Below is a list of species that possibly possess hydathodes, Eoplatanus serrata (Figure 13, 2-5; Figure 16, 15), Aspidiophyllum denticulatus (Figure 15, 3-5), Dischidus quinquelobus (Figure 20, 1-3), Crassidenticulum trilobus (Figure 21, 1-7; Figure 22, 1-2), Crassidenticulum serratus (Figure 27, 9), Dicotylophyllum expansolobum (Figure 37, 78), Credneria cyclophylla (Figure 55, 7), Glandilunatus minnesotense (Figure 54, 1-2), Crassidenticulum cracendentis (Figure 59, 1-5), Eurylobum dentatum (Figure 69, 1-2). The presence of hydathodes in these plants indicates that these plants live very close to wet, mesic environments with high humidity. The presence of fungal growth on many Eoplatanus serrata leaves (Figure 14, 5-7) from the BraunÂ’s Ranch locality may also

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358 indicate warm temperatures and high moisture levels because these conditions are ideal for the growth of fungi. Leaf Morphology Many paleobotanists have long noted that the leaf morphology of woody dicotyledons varies with climate and have applied this in the estimation of paleoclimate parameters. For example, the percentage of species with entire-margined leaves tends to increase with increasing temperature, while leaf size tends to increase with increasing precipitation (Bailey and Sinnott, 1915; Wolfe, 1979; Givnish, 1987; Wolfe, 1993; Wilf, 1997, 1998; Wilf and Wing, 1998; Wilf et al., 1999). Many angiosperm species from the Dakota Formation, i.e., Eoplatanus serrata (Figure 13, 1; Figure 13, 6), Dischidus quinquelobus (Figure 20, 1; Figure 20, 4), Meiophyllum expansolobum (Figure 38, 3-4), Sapindopsis bagleyae (Figure 39, 1; Figure 40, 3; Figure 41, 1-3), Citrophyllum alteruans (Figure 48, 1; Figure 48, 4), and Credneria cyclophylla (Figure 55, 2), have leaves that possess a distinctive swollen petiole base and/or with stipules (The original function of stipules is unknown, but may have been invol ved as protection for the emerging leaf buds). Leaves of many species possess very large leaf sizes. Meiophyllum expansolobum has leaves up to 22 cm long by 20 cm wide. Liriophyllum kansense has leaves up to 18.5 cm long by 20 cm wide. Pabiania cf. P. groenlandica has leaves up to 13.5cm long by at least 20 cm wide. Other platanoid and Sapindopsis -type species also have large leaves. Biological degradation is rare. Fungal growth only observed on Eoplatanus serrata leaves (Figure 14, 5-7). The lack of biological degradation was considered as evidence of deciduousness by Spicer and Parrish (1986). These characters, i.e., swollen petiole base and large leaf size indicate the deciduousness of these species,

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359 which is in turn an indication of the presence of seasonality and possibly high precipitation on the eastern margin of the Western Interior Seaway. Conclusions and Perspectives Leaf morphology indicates warm, wet, mesic environments with high humidity on the eastern margin of the Western Interior Seaway during the mid-Cretaceous. Seasonality at this time is implied by the presence of deciduous angiosperm species. In order to quantify the relationships between leaf morphology and paleoclimate parameters, more collections are needed from existing and some potential localities.

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360 CHAPTER 5 COMPARISON WITH THE POTOMAC GROUP OF THE EASTERN UNITED STATES Background Study The Potomac Group has an outcrop extending discontinuously in a belt up to 30km wide from the Nottoway, Appomattox, and James Rivers south of Richmond, Virginia, through Frederichsburg, Virginia, Washington, DC, Baltimore, Maryland, northeastern Maryland and adjacent Delaware, and an uncertain distance into New Jersey (Hickey and Doyle, 1977). In its type area, the Potomac Group was divided into three or four formations (Clark and Bibbins, 1897) with an age ranging from Late Barremian (Lower Patuxent Formation) to Cenomanian (“Raritan” Formation). In ascending order, they are Patuxent Formation, Arundel Clay, Patapsco Formation, and "Raritan" Formation (Hickey and Doyle, 1977). Based on biostratigraphic studies, primarily palynostratigraphic research, three palynological zones have been proposed for the Potomac Group with the middle zone further divided into three subzones (Clark and Bibbins, 1897; Doyle, 1992; Upchurch et al ., 1994). In ascending stratigraphic order, they are: Zone I: early to middle Aptian; Zone II: late Aptian to late Albian; Subzone II-A: late Aptian to possibly early Albian; Subzone II-B: early Albian to early late Albian; Subzone II-C: late Albian;

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361 Zone III: early to middle Cenomanian. Formal systematic treatment of the Potomac angiosperm leaf megafossils using modern methods or foliar architectural analysis has never been published except the paper by Upchurch et al. (1994). In this paper, an Early Cretaceous angiosperm leaf megaflora from the Quantico locality of the Potomac Group of Virginia was comprehensively described and illustrated. Two other papers (Doyle and Hickey, 1976; Hickey and Doyle, 1977) primarily focused on early angiosperm evolution with only preliminary analyses of angiosperm leaf systematics. Comparison Between the Dakota Flora and the Potomac Flora Zone I In this zone the Potomac Group, angiosperm leaves only account for a very small portion of the total Zone I flora, which consists of five species in the lower part of the zone to ten or twelve above (Hickey and Doyle, 1977). Five of the illustrated species by Hickey and Doyle (1977), i.e., Rogersia angustifolia Fontaine, Acaciaephyllum spatulatum Fontaine, Celastrophyllum latifolium Fontaine, Proteaephyllum reniforme Fontaine, and Eucalyptophyllum oblongifolium Fontaine, are entire margined and three, i.e., Proteaephyllum dentatum Fontaine, Quercophyllum tenuinerve Fontaine, and Vitiphyllum multifidum Fontaine are toothed. Leaves from this zone are simple (no pervasive asymmetry typical of leaflets of compound leaf), small (most of them no more than 5 cm long) and only elliptic, ovate, and obovate shape classes are recognized. However, leaves of Ficophyllum crassinerve (from the upper part of the Zone) reach 20 cm in length. As summarized by Hickey and Doyle (1977), the most unusual aspect of Zone I leaves is the disorganized venation with irregular size and shape of the intercostal areas enclosed by the secondary veins, irregular ramifying courses and poor

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362 differentiation of the tertiary and higher order veins. Together with poor differentiation of the petiole from the blade, these characters are considered by Hickey (1971) as “first rank” leaf architecture syndrome, which is primitive in eudicots. These primitive characters are also observed in the Dakota Flora angiosperm leaves, for example, Rogersia parlatorii Fontaine (Figure 17, 1-6; Figur e 17, 10; Figure 18, 1-11; Figure 23, 1) from the Braun’s Ranch locality of Kansas. Another species, Quercophyllum tenuinerve Fontaine, which has irregularly spaced and doubly convex teeth with a large glandular area near the apex, was found in the Pleasant Dale locality of Nebraska (Figure 64, 8) It is worth noting that almost all the angiosperm leaves from zone I are restricted to sandstone or sandy beds with cross bedding or cross lamination, or micaceous mudstone beds intimately associated with coarser sediment, while conifer cycadopsid, and fern remains are found in equivalent finer grained, parallel bedded units (Hickey and Doyle, 1977). On the contrary, the Dakota Formation angiosperm fossils are much more diverse. Angiosperm leaf fossil can be f ound almost in every sedimentary environment, which indicates that by this time, the angiosperms dominated almost in every environment. Zone II-B The research of Upchurch et al. (1994) is the first to comprehensively describe and illustrate the early Cretaceous Potomac angiosperm megaflora using modern methods of foliar architectural analysis. Based on overall floral composition, Upchurch et al. (1994) placed the Quantico megaflora within Subzone II-B of Brenner (1963) and probably the upper part of Sub-zone II-B (Middle to early late Albian; Doyle and Robins,

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363 1977). This flora consists of 12 angiosperm leaf species. Their formal systematic assignment is listed as below: Division MAGNOLIOPHYTA (Angiosperms) Order LAURALES aff. Pabiania sp. 1 Upchurch et al. 1994 Landonia cf. L. calophylla Upchurch and Dilcher 1990 Dicotylophyllum ovata-decurrens Upchurch et al. 1994 Order PROTEALES Nelumbites extenuinervis Upchurch et al. 1994 Nelumbites cf. N. minimus Vakhremeev 1975 Sapindopsis magnifolia/variabilis Fontaine 1889 Sapindopsis minutifolia Upchurch et al. 1994 Fragments of platanoid foliage Clade UNKOWN Dicotylophyllum sp. 1 (cf. D. argillaceum [Velenovsky] Vakhrameev) Upchurch et al. 1994 Dicotylophyllum sp.2 (cf. “ Magnolia ” amplifolia Heer?) Upchurch et al. 1994 Dicotylophyllum sp. 3 (aff. Didromophyllum Upchurch and Dilcher?) Upchurch et al. 1994 Dicotylophyllum sp. 4 Upchurch et al. 1994 The Quantico assemblage and the Hoisington III locality of Kansas are the most similar in floral composition. Three of seven identified genus are present in the Hoisington III locality, i.e., Pabiania , Sapindopsis , and Nelumbites. Nelumbites is a common element in both localities (> 100 specimens observed from the Quantico locality and 70 specimens are observed from the Hoisington III locality). The similarity of floristic composition of these two localities was probably resulted from similar sedimentary environments. The Hoisington III locality was interpreted as a fresh-water lake or brackish water lagoon environment with river influence (Retallack and Dilcher, 1981; Skog et. al., 1992; Skog and Dilcher, 1994), while the Quantico locality was interpreted as a pond or swale (Upchurch et al., 1994). However, the Quantico assemblage (12 species) is less diverse than the Hoisington III assemblage (27 species).

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364 In this Zone at other localities, aquatic plants such as Menispermites virginiensis Fontaine, Menispermites “tenuinervis” Fontaine. Pinnately and palmately lobed leaves appeared in the late middle Albian ( Sapindopsis magnifolia Fontaine from Brooke locality). However, these Sapindopsis leaves have variable pattern of lobation (two or three apical lobes and with varying degrees of decurrent of the lobes onto the rachis), and the rachis always bears at least narrow wings of laminar tissue that are continuous with the lobes. The venation pattern of these leav es are irregular (secondary venation irregular brochidodromous). On the contrary, Sapindopsis leaves from the Hoisington III locality shows that the leaflets possess a distinctive petiole, sometimes the petiole can be up to 3.5 cm long (Figure 42, 1). Three species have been recognized from the Hoisington III locality, all of them are pinnately compound leaves with leaflet attached to the rachis by a distinct petiole except those ultimate leaflets, more regular patterns of secondary and tertiary veins with the tertiaries tending to be oriented perpendicular to leaflet primary vein. In the Potomac Group, Sapindopsis leaves with similar characters appeared in the upper part of subzone II-B. Most of the palmately lobed leaves (for example, Araliaephyllum obtusilobum Fontaine) from Subzone II-B are characterized by two lateral large lateral lobes, palinactinodromous primary venation, secondary venation only moderately regular, and tertiary veins are weak and irregular. On the other hand, similar leaves, for example, Eoplatanus serrata (Figure 13, 1-10; Figure 14, 1-7; Figure 15, 1; Figure 15, 2; Figure 15, 6; Figure 16, 1-15) and Aspidiophyllum denticulatus (Figure 15, 3-5) from the Braun’s Ranch locality, Aspidiophyllum obtusum (Figures 68, 1-6; Figure 71, 2; Figure

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365 71, 4-5) and Eurylobum dentatum (Figures 69, 1-2; Figure 69, 4-5; Figure 70, 1-4) from the Springfield locality have more regular secondary and tertiary venation. Subzone II-C and Zone III In this zone from the Potomac Group, angiosperm leaves are dominantly by new members of the platanoid complex, for example, Araliopsoides cretacea (Newberry) Berry and derived unlobed pinnately veined leaves (Hickey and Doyle, 1977). Both forms have occurrence in the Dakota Flora, for example, Credneria cyclophylla (Heer) Wang (Figure 34, 4-6; Figure 55, 1-7) fr om Courtland I locality, Minnesota, and Credneria quadratus (Lesquereux) Wang (Figure 24, 1-3) from the Braun’s Ranch locality, Kansas. These species possess a distinctive character, i.e., “having higher third rank venation with rigidly percurrent tertiary veins and ‘stitched intertertiary’ formed by branching and fusion of the alternating quaternary veins” (Hickey and Doyle, 1977). Other similar species occurring both in the Potomac and Dakota Floras are the Liriophyllum -like leaves (considered by Hickey and Doyle as transitional forms) such as Citrophyllum and Liriophyllum (Dilcher and Crane, 1984a; Upchurch and Dilcher, 1990). The five lobed species, “Aralia” quinquepartita Lesquereux, which is considered as the forerunner of the palinactinodromously compound genus Dewalquea by Hickey and Doyle (1977) also has similar leaves from the Hoisington III locality, Kansas, Rose Creek I locality and Pleasant Dale locality, Nebraska, i.e., Meiophyllum expansolobum (Figure 37, 1-6; 38, 1-8; Figure 64, 1-2). Conclusion In general, some of the archaic characters (such as poor differentiation of the vein orders that is still seen on some modern angiosperms, i.e., Illiciaceae) are still observed in some of the Dakota Flora elements. The Dakota Flora is much more diverse than the

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366 Potomac in species richness. Many elements from the Dakota Formation possess characters (for example, regularity of venation patters and more variation of other morphological characters). Based on floral composition and morphological characters, the Hoisington III assemblage of Kansas probably represents the oldest assemblage in the Dakota Flora. It is most closely related to some of the Potomac assemblages, i.e., the Quantico assemblage (Hickey and Doyle, 1977; Upchurch et al., 1994), but it is more advanced.

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367 CHAPTER 6 CONCLUSIONS, PROBLEMS, AND PERSPECTIVES Conclusions In this project, 87 angiosperm species are recognized from the Dakota and there are 7 to 20 species from each locality. The diversity of the Dakota Flora probably was neither as high as that proposed by Lesquereux (1892), nor as low as that suggested by Lidgard and Crane (1988). I propose a conservative estimate of about 150 to 200 species, including Lesquereux’s (1892) sandstone coll ections, from the Dakota Flora during the mid-Cretaceous. There is less than 25% species overlap between any two localities except between Pleasant Dale and Courtland I localities, which is apparently the result of insufficient collection of the Pleasant Dale locality. At present, the high diversity of angiosperms restricted to a single locality can best be interpreted as the result of environmental effects (Retallack and Dilcher, 1986). At this time, there is no reliable dating of these megafossil localities, which also could account fro species difference if the time for the deposition of the flora extended over many million years. Most of the dominant elements of the Dakota Flora belong to Magnoliales, Laurales, and Proteales. Elements from these three orders are also common dominant members at individual localities. Leaf morphology indicates warm, wet, mesic environments with high humidity on the eastern margin of the Western Interior Seaway during the mid-Cretaceous. Seasonality at this time is implied by the presence of deciduous angiosperm species.

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368 Problems and Perspectives As suggested by Hickey and Doyle (1977), to minimize the problems of convergence and mosaic evolution, evidence of a single organ (character) is seldom decisive; it must be weighted in the light of evidence of other organs (characters). Cuticles of leaves, which are very well preserved in some localities, can provide more information on the systematics. As many approaches as possible should be applied to the study of the Dakota Flora angiosperms. One approach is not more valuable than another, nor does the data obtained offer any more important answers to Dakota Formation angiosperm diversity and evolution. The resu lts from combined approaches will certainly provide a more complete picture of diversity and evolution of angiosperms during the mid-Cretaceous (Dilcher, 2001). Due to the lack of other direct and indirect dating methods, palynostratigraphy seems to be very important in this area for stratigraphic correlation. Witzke et al. (1996) set up a palynostratigraphic framework with four general palynostratigraphic units for the Dakota Formation on the eastern margin of the western Interior Seaway. In ascending order, these are: 1) A basal Dakota (lower Nishnabotna Member) assemblage of mid-Late Albian age (equivalent to Kiowa Formation) with marine palynomorphs associated in southeast Nebraska; 2) A lower to mid Dakota (Terra Cotta and basal Woodbury) assemblage equivalent in part to the Muddy Sandstone of Wyoming; 3) A mid to upper Dakota (lower Woodbury Member, early Cenomanian) assemblage; and 4) Upper Dakota (middle to upper Woodbury and Janssen Clay members, middle and late Cenomanian) assemblages. Once analysis of palynology for each megafossil locality is available, it will be possible to correlate all the megafossil localities with zonation scheme. The relative age of each megafossil locality will be relatively more accurately determined.

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369 This can be accomplished by comparing the pollen and spore assemblages obtained from each locality with the zonation scheme, the same methods employed by Hickey and Doyle (1977) to the Potomac Formation. Palynostratigraphic studies provide a more precise and reliable means of relative dating for isolated sections (localities) within the Dakota Formation. A comprehensive palynologic zonation of the Dakota Formation will benefit studies of the megaflora in three major ways as suggested by Upchurch et al. (1994) for the Potomac Group. Palynostratigraphy will permit evolutionary trends within leaf megafossils to be inferred independently of megaflora zonation schemes and can avoid circular reasoning. It will be able to correct correlation errors made by early workers on the basis of megaflora remains, and will be able to provide a check on intraformational correlations based on inferred lithostratigraphic position within the Dakota Formation. In order to access the effects of geographic and/or stratigraphic effects on diversity pattern, at least two or three more localities are needed from Iowa (figure 1). Collections from existing localities such as Pleasant Dale and Springfield locality are also critically needed in order to use angiosperm leaves as paleoclimate proxy for the Cretaceous. At least twenty species are needed in order to estimate the paleoclimate parameters more accurately (Wolfe, 1993; Wilf, 1997; Wilf, 1998; Wilf and Wing, 1998; Wilf et al., 1999; Burnham et al., 2001). Further collections at existing individual localities should be focused on increasing sample numbers. As suggested by Burnham and Wing (1992), an individual sample of 350 to 400 leaves will probably recover most of the species that could have shed leaves onto the sample site in modern deciduous forest communities. At least this

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370 information should be properly documented in fu ture field trips to these existing localities because this information is critical in assessing features of paleo-forests such as dominance, heterogeneity, and growth form (Burnham and Wing, 1992). Multiple sampling from a range of different sub-e nvironments (including Sandstone specimens which are formed in sub-environments such as channels from the floodplain) will improve the accuracy of the analysis of angiosperm diversity, as well as analyses of paleoecology and paleoclimate (Burnham, 1989).

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371 APPENDIX A SPECIES DISTRIBUTION OF ANGISOEPRM LEAF MEGAFOSSILS IN THE SIX LOCALITIES OF THE DAKOTA FORMAION BR-BraunÂ’s Ranch, Kansas; HO-Hoisington III, Kansas; RC-Rose Creek I, Nebraska; PD-Pleasant Dale, Nebraska; SP-Springfield, Nebraska; CD-Courtland I, Minnesota. Order/family Genus/species BR HO RC PD SP CD New genus A 0 0 1 0 0 0 Liriophyllum siemia 0 0 0 0 0 6 Liriophyllum kansense 0 30 0 0 0 0 Jarzenia kanbrasota 0 2 0 13 0 7 Magnoliales Jarzenia reticulatus 0 0 0 0 0 1 Crassidenticulum decurrens 125 2 130 0 0 0 Crassidenticulum cracendentis 0 0 0 0 0 3 Crassidenticulum trilobus 58 1 0 0 0 0 Crassidenticulum variloba cf. trilobus 0 2 0 0 0 0 Crassidenticulum landisia 13 0 0 0 0 0 Yangia glandifolium 2 0 0 0 0 0 Densinervum kaulii 0 0 6 0 0 6 Landonia calophylla 0 0 1 0 0 0 cf. Chloranthaceae Landonia mullerii 1 0 0 0 0 0 Pabiania variloba 0 56 150 0 4 0 Pabiania groenlandica 0 34 1 0 0 0 Pabiania cf. P. groenlandica 0 1 0 0 0 0 Setterholmia rotundifolia 0 0 0 0 0 10 Setterholmia callii 0 0 0 0 0 3 Setterholmia deleta 0 0 0 0 0 1 Manchesterii macrophylla 0 0 0 16 0 2 Pandemophyllum kvacekii 0 0 70 0 0 5 Pandemophyllum attenuatum 0 0 7 0 0 14 Pandemophyllum gracifolia 0 0 0 0 0 3 Pandemophyllum sp. 0 0 1 0 0 0 Rogersia kansense 200 0 0 43 0 38 Rogersia potteri 0 1 0 0 0 0 Rogersia parlatorii 195 0 0 50 0 0 Rogersia lottii 1 0 0 0 0 0 Laurales / cf. Lauraceae Rogersia cf. R. parlatorii 0 0 0 13 0 0

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372 Order/family Genus/species BR HO RC PD SP CD Wolfiophyllum daphneoides 4 0 0 0 0 0 Wolfiophyllum heigii 17 0 0 0 0 0 Laurales / cf. Lauraceae Wolfiophyllum pfaffiana 0 3 0 0 0 26 Longstrethia varidentata 0 0 98 0 0 0 cf. Illiciales Longstrethia aspera 0 2 0 0 0 0 Didromophyllum basingerii 0 0 12 0 0 0 Acritodromum ellipticum 0 0 1 0 0 0 Reynoldsiophyllum masonii 0 0 2 0 0 0 Reynoldsiophyllum nebrascense 0 0 4 0 0 0 Dicotylophyllum angularis 0 0 5 0 0 0 Dicotylophyllum leptovena 0 1 0 0 0 1 Dicotylophyllum crasseprimus 0 0 0 0 0 1 Dicotylophyllum tulipifera 0 0 0 0 0 1 New genus B 0 0 2 0 0 0 Skogia leptoselis 0 1 0 0 0 0 Clades unknown Sungia delicatus 0 0 0 9 0 0 Nelumbites fluitus 0 35 0 0 0 0 Nelumbites crassinervum 0 30 0 0 0 0 Proteales / cf. Nelumbonaceae Nelumbites farleyi 0 5 0 0 0 0 Sapindopsis retallackii 0 1 0 1 28 0 Sapindopsis bagleyae 0 110 0 0 0 0 Sapindopsis beekeria 0 3 0 0 0 0 Anisodromum wolfei 0 3 6 0 0 0 Anisodromum upchurchii 0 4 0 0 0 0 Citrophyllum doylei 0 0 1 0 0 0 Citrophyllum alteruans 0 6 0 0 0 0 Credneria quadratus 1 0 0 0 0 0 Credneria cyclophylla 0 3 0 0 0 36 Credneria cf. C. cyclophylla 0 0 0 1 0 0 Dischidus quinquelobus 1 0 0 0 0 0 Eoplatanus serrata 718 0 0 0 0 0 Aspidiophyllum denticulatus 2 0 0 0 0 0 Aspidiophyllum obtusum 0 0 0 0 16 0 Proteales / aff. Platanaceae Eurylobum dentatum 0 0 0 0 26 0 Trochodendroides rhomboideus 0 0 0 1 0 12 Saxifragales / cf. Cercidiphyllaceae Trochodendroides cf. T. rhomboideus 3 0 0 0 0 0 Crepetii minudentis 0 0 0 0 0 2 Glandilunatus minnesotense 1 0 0 0 0 8 Hickeyphyllum sandersia 5 0 0 0 0 0 Clade unknown Hickeyphyllum imhofia 1 0 0 0 0 0

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373 Order/family Genus/species BR HO RC PD SP CD Jaramillophyllum celatus 0 1 0 0 0 0 Kladoneuron ravenia 1 0 0 0 0 0 Quercophyllum tenuinerve 0 0 0 1 0 0 Meiophyllum expansolobum 0 54 1 2 0 0 Meiophyllum kowalskiae 0 2 0 0 0 0 ?Menispermites sp. 0 0 0 0 1 0 Wingia anisos 0 2 0 0 0 0 Dicotylophyllum braunii 1 0 0 0 0 0 Dicotylophyllum fragilis 1 0 0 0 0 0 Dicotylophyllum myrtophylloides 0 0 1 0 0 0 Dicotylophyllum rosafluviatilis 0 0 1 0 0 0 Dicotylophyllum aliquantuliserratum 0 0 5 0 0 0 Dicotylophyllum denticulatus 0 0 0 1 0 0 Dicotylophyllum carlsonia 0 0 0 0 0 1 Dicotylophyllum coughlantia 0 0 0 0 0 2 Dicotylophyllum huangia 1 0 0 0 0 0 Clade unknown Dicotylophyllum sp. 2 0 0 0 0 0

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374 APPENDIX B INDEX OF ANGIOSPERM SPECIES FROM THE DAKOTA FORMATION Anisodromum upchurchii sp. nov. (Figure 43, 1-2; Figure 43, 5) Anisodromum wolfei Upchurch and Dilcher 1990 (Figure 42, 2-3; Figure 42, 5-6) Aspidiophyllum denticulatus sp. nov. (Figure 15, 3-5) Aspidiophyllum obtusum (Lesquereux) new combination (Figure 68, 1-6; Figure 71, 2, Figure 71, 4-5) Citrophyllum alteruans (Heer) new combination (Figure 48, 1-7) Crassidenticulum cracendentis sp. nov. (Figure 59, 1-5) Crassidenticulum decurrens Upchurch and Dilcher 1990 (Figure 13, 1-10; Figure 26, 1-3; Figure 36, 5-6) Crassidenticulum landisae sp.nov. (Figure 27, 1-9; Figure 28, 1-5) Crassidenticulum trilobus sp. nov. (Figure 21, 1-8; Figure 22, 1-6; Figure 23, 6-8; Figure 36, 2) Crassidenticulum variloba cf. trilobus sp. nov. (Figure 34, 1; Figure 36, 1) Credneria cyclophylla (Heer) new combination (Figure 34, 4-6; Figure 55, 1-7) Credneria cf. C. cyclophylla (Heer) sp. nov. (Figure 64, 4-5) Credneria quadratus (Lesquereux) new combination (Figure 24, 1-3) Crepetia minudentis sp. nov. (Figure 56, 1-7) Densinervum kaulii Upchurch and Dilcher 1990 (Figure 60, 1; Figure 60, 5-6; Figure 60, 9-10) Dicotylophyllum braunii sp. nov. (20, 5-6) Dicotylophyllum carlsonia sp. nov. (Figure 52, 3) Dicotylophyllum coughlantia sp. nov. (Figure 57, 1-8) Dicotylophyllum crasseprimus sp.nov. (Figure 59, 6-7) Dicotylophyllum denticulatus sp. nov. (Figure 64, 6) Dicotylophyllum fragilis sp. nov. (Figure 15, 8-9)

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375 Dicotylophyllum huangia sp. nov. (Figure 30, 5-6) Dicotylophyllum leptovena sp. nov. (Figure 34, 2; 37. 8; Figure 51, 8-9, Figure 51, 14) Dicotylophyllum tulipifera (Heer) new combination (Figure 54, 10-12) Dicotylophyllum sp. (Figure 24, 4-6) Dischidus quinquelobus sp. nov. (Figure 20, 1-4) Eoplatanus serrata Schwarzwalder and Dilcher 1986 (Figure 13, 1-10; Figure 14, 1-7; Figure 15, 1; Figure 15, 2; Figure 15, 6; Figure 16, 1-15) Eurylobum dentatum (Lesquereux) Schwarzwalder and Dilcher (Figure 69, 1-2; Figure 69, 4-5; Figure 70, 1-4) Glandilunatus minnesotense sp. nov. (Figure 15, 7; Figure 29, 5; Figure 54, 1-5) Trochodendroides rhomboideus (Lesquereux) Berry 1922 (Figure 51, 1-7, Figure 51, 10; Figure 64, 7) Trochodendroides cf. T. rhomboideus (Lesquereux) Berry 1922 (Figure 30, 1-4) Hickeyphyllum imhofia sp. nov. (Figure 19, 9-10) Hickeyphyllum sandersia sp. nov. (Figure 19, 4-6) Jaramillophyllum celatus (Lesquereux) new combination (Figure 32, 1) Jarzenia kanbrasota sp. nov. (Figure 43, 6-7; Figure 50, 1-6, Figure 50, 9-10; Figure 63, 5-8) Jarzenia reticulatus sp. nov. (Figure 53, 1-3) Kladoneuron gooleria sp. nov. (Figure 23, 2-4) Landonia mullerii sp. nov. (Figure 23, 5) Liriophyllum kansense Dilcher and Crane 1984 (See Dilcher and Crane 1984) Liriophyllum siemia sp. nov. (Figure 50, 11; Figure 58, 1-2; Figure 58, 6-7, Figure 58, 10-11) Longstrethia aspera (Lesquereux) new combination (Figure 44, 1-2; Figure 44, 5) Manchesterii macrophylla (Lesquereux) Wang comb. nov. (Figure 61, 1-6; Figure 52, 1-2; Figure 52, 4-6) Meiophyllum expansolobum (Upchurch and Dilcher) new combination (Figure 37, 1-6; Figure 38, 1-8; Figure 64, 1-2) Meiophyllum kowalskiae sp. nov. (Figure 34, 6; Figure 37, 7-8) ? Menispermites sp. (Figure 68, 7) Nelumbites farleyi sp. nov. (Figure 46, 6-7) Nelumbites fluitus sp. nov.

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376 (Figure 45, 1-7; Figure 46,1; Figure 46,3-4; Figure 47,2) Nelumbites crassinervum sp. nov. (Figure 46, 2; Figure 47,1; Figure 47,3-6) Pabiania groenlandica (Heer) new combination (Figure 31, 1-7) Pabiania cf. P. groenlandica (Heer) Wang (Figure 33, 5) Pabiania variloba Upchurch and Dilcher 1990 (Figure 33, 1-4, Figure 33, 6-7; Figure 71, 1; Figure 71, 3; Figure 71, 6) Pandemophyllum attenuatum Upchurch and Dilcher 1990 (Figure 53, 4-11) Pandemophyllum gracifolia sp. nov. (Figure 53, 12-14) Pandemophyllum kvacekii Upchurch and Dilcher 1990 (Figure 54, 6-9) Quercophyllum tenuinerve Fontaine 1889 (Figure 64, 8) Rogersia kansense Wang sp. nov. (Figure 35,1-4; Figure 35,6; Figure 35, 8; Figure 50, 7; Figure 51, 11-13, Figure 51, 1516; Figure 60, 4; Figure 63, 4; Figure 64, 3; Figure 65, 1-4) Rogersia lottii sp. nov. (Figure 19,1-3) Rogersia parlatorii Fontaine 1889 (Figure 17, 1-6; Figure 17, 10; Figure 18,1-11; Figure 23, 1; Figure 65, 5-9) Rogersia potteri sp. nov. (Figure 32, 2-3) Rogersia cf. R. parlatorii Fontaine 1889 (Figure 65, 10-11) Sapindopsis bagleyae sp. nov. (Figure 40, 1-5; Figure 39,1-7;Figure 41, 1-7) Sapindopsis beekeria sp. nov. (Figure 35,5; Figure 42, 1; Figure 43, 4) Sapindopsis retallackii sp. nov. (Figure 36, 3-4; Figure 66, 1-8; Figure 67, 1-5; Figure 63, 1-2) Setterholmia callii sp. nov. (Figure 49, 1; Figure 49, 8) Setterholmia deleta (Lesquereux) new combination (Figure 60, 7-8) Setterholmia rotundifolia (Lesquereux) new combination (Figure 49, 2-7; Figure 49, 9-10) S kogia leptoselis sp. nov. (Figure 44, 6-7) Sungia delicatus sp. nov. (Figure 62, 1-5) Wingia anisos sp. nov. (Figure 43, 3-4) Wolfiophyllum daphneoides (Lesquereux) new combination (Figure 26, 4-6) Wolfiophyllum heigii sp. nov. (Figure 17, 7-9, Figure 17, 11-12; Figure 19, 7-8)

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377 Wolfiophyllum pfaffiana (Heer) Wang new combination (Figure 35,7; Figure 44, 3-4; Figure 56, 8-12; Figure 58, 3-5, Figure 58, 8-9; Figure 60, 2-3) Yangia glandifolium sp. nov. (Figure 29, 1-4; Figure 30, 7-8) [Note: The following species are not illustrated in this dissertation. See Upchurch and Dilcher (1990) for illustrations.] Acritodromum ellipticum Upchurch and Dilcher 1990 Citrophyllum doylei Upchurch and Dilcher 1990 Dicotylophyllum angularis Upchurch and Dilcher 1990 Dicotylophyllum aliquantuliserratum Upchurch and Dilcher 1990 Dicotylophyllum myrtophylloides Upchurch and Dilcher 1990 Dicotylophyllum rosafluviatilis Upchurch and Dilcher 1990 Didromophyllum basingerii Upchurch and Dilcher 1990 Landonia calophylla Upchurch and Dilcher 1990 Longstrethia varidentata Upchurch and Dilcher 1990 New genus A New Genus B Pandemophyllum sp. Upchurch and Dilcher 1990 Reynoldsiophyllum masonii Upchurch and Dilcher 1990 Reynoldsiophyllum nebrascense Upchurch and Dilcher 1990

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APPENDIX C EXPLANATION OF DIVERSITY INDICES The following list contains the explanation of different indices used in the diversity analysis in the PAST program (from Hammer et. al., 2001). Association indices: Dominance index. It ranges from 0 (all taxa are equally present) to 1 (one taxon dominates the community completely). Simpson index = 1-dominance. It measures “evenness” of the community from 0 to 1. Shannon index: It varies from 0 (communities with only a single taxon) to high values for communities with many taxa, each with few individuals. Menhinick index: the ratio of the number of taxa to the square root of sample size. Margalef index: (S-1)/ ln (n) , where S is the number of taxa, and n is the number of individuals. Fisher's alpha: a diversity index, defined implicitly by the formula S=a* ln (1+n/a) where S is number of taxa, n is number of individuals and a is the Fisher's alpha. Association similarity indices: Dice and Jaccard similarity indices are used to compare associations based on absence/presence data. When comparing two columns (associations), a match is counted for all taxa with presences in both columns. Dice similarity = 2M / (2M+N) and Jaccard similarity = M / (M+N) where M is the number of matches and N is the total number of taxa with presences in just one column. A matrix is presented with the comparisons between all pairs of associations. The Simpson index is defined as M / Nmin, where Nmin is the smaller of the numbers of presences in the two associations. The Raup-Crick similarity index uses a randomization ("Monte Carlo") procedure, comparing the observed number of species occurring in both associations with the distribution of co-occurrences from 200 random replicates. It is used to compare associations based on absence/presence data. All these indices range from 0 (no similarity) to 1 (identity). Input data is a matrix with two or more columns of presence/absence (0/1) data with taxa down the rows.

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379 REFERENCES Andrews, H.N., 1970. Index of Generic Names of Fossils Plants, 1820-1965. U.S. Geological Survey Bulletin 1300. United States Government Printing Office, Washington 354 pp. Arthur, M.A. and Dean, W., 1986. Cretaceous Paleoceanography. In: B.E. Tucholke and P.R. Vogt (Editors), Decade of North American Geology, Western North Atlantic Basin Synthesis Volume, Geologi cal Society of America, pp.617-630. Austin, G.S., 1970. Weathering of the Sioux Quartzite near New Ulm, Minnesota, as related to Cretaceous climate. Journal of Sedimentary Petrology, 40: 184-193. Bailey, I.W. and Sinnott, E.W., 1915. A botanical index of Cretaceous and Tertiary climates. Science, 41: 831–834. Barnard, P., 1973. Mesozoic Floras. In: N. Hughes (Editor), Organisms and Continents Through Time: Special Paper on Paleontology, 12: 175-188. Barron, E.J., 1983. A warm, equable Cretaceous: The nature of the problem. Earth Science Review, 19: 305-338. Barron, E.J. and Washington, W.M., 1982. Cretaceous climate: a comparison of atmospheric simulations with the geologic record. Paleogeography, Paleoclimatology, and Paleoecology, 40: 103-133. Barron, E.J., Thompson, S.L. and. Schneider, S.H., 1981. An ice-free Cretaceous? Results from climate model simulation. Science, 212: 501-508. Basinger, J.F. and Dilcher, D.L., 1984. Ancient bisexual flowers. Science, 224: 511-513. Bayne, C.K., Franks, P.C. and Ives, W. JR, 1971. Geology and ground water resources of Ellsworth County, central Kansas. Kansas Geological Survey Bulletin, 201: 1-84. Berner, R.A., 1993. Paleozoic atmospheric CO2: Importance of solar radiation and plant evolution. Science, 261: 68-70. Berner, R.A., 1994. CEOCARB II: a revised model of atmospheric CO2 over Phanerozoic time. America Journal of Science, 294: 56-91.

PAGE 388

380 Berner, R.A., Lasaga, A.C. and Garrels, R.M., 1983. The carbonate-silicate geochemical cycle and its effect on atmospheric carbon dioxide over the past 100 million years. American Journal of Science, 283: 641-683. Berry, E.W., 1911. Systematic Paleontology, Lower Cretaceous Fossil Plants. In: W.B. Clark (Editor), Lower Cretaceous. Maryland Geological Survey, Baltimore, pp.214508. Berry, E.W., 1916. The Upper Cretaceous Floras of the World. In: W.B. Clark (Editor), Upper Cretaceous. Johns Hopkins Press, Baltimore, pp.83-313. Berry, E.W., 1920. Age of the Dakota Flora. American Journal of Science (4th series), 50: 387-390. Berry, E.W., 1922a. The flora of the Woodbine Sand at Arthurs Bluff, Texas. U.S. Geological Survey Professional Paper, 129: 153-181. Berry, E.W., 1922b. The flora of the Cheyenne Sandstone of Kansas. U.S. Geological Survey Professional Paper, 129: 199-225. Berry, E.W., 1923. Tree Ancestors: a glimpse into the past. Baltimore, Williams and Wilkins Co. 268 pp. Bowe, R.J., 1972. Depositional history of the Dakota Formation in eastern Nebraska. Master thesis, Geology Department, University of Nebraska-Lincoln. 87 pp. Brenner, G.J., 1963. The spores and pollen of the Potomac Group of Maryland. State of Maryland Department of Geology, Mines, and Water Resources Bulletin, 27: 1-215. Brenner, R.L., Bretz, R.F., Bunker, B.J., Iles, D.L., Ludvigson, G.A., McKay, R.M., Whitley, D.L. and Witzke, B.J., 1981. Road Log and Stop Descriptions. In: R.L. Brenner (Editor), Cretaceous Stratigraphy and Sedimentation in Northwest Iowa, Northeast Nebraska, and Southeast South Dakota: Iowa Geological Survey, Guide Book 4, pp.149-172. Brenner, R.L., Ludvigson, G.A., Witzke, B.J., Zawistoski, A.N., Kvale, E.P., Ravn, R.L. and Joeckel R.M., 2000. Late Albian Kiowa-Skull Creek marine transgression, Lower Dakota Formation, eastern margin of Western Interior Seaway, USA. Journal of Sedimentary Research, 70(4): 868-878. Brongniart, A., 1822. Sur la classification et la distribution des vegetaux fossiles en general, et sur ceux des terrains de sediment superieur en particulier. Mus. Historie Natl. (Paris) Mem., 8: 203-348. Bunce, R.G. and Shaw, M.W., 1973. A standardized procedure for ecological survey. Journal of Environ. Manag., 1: 101-110.

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381 Burnham, R.J., 1989. Relationships between standing vegetation and leaf litter in a paratropical forest: implications for paleobotany. Review of Palaeobotany and Palynology, 58: 5-32. Burnham, R.J., 1993a. Reconstructing richness in the plant fossil record. Palaios, 8: 376384. Burnham, R.J., 1993b. Time resolution in terrestrial macrofloras: guidelines from modern accumulations. In: S.M. Kidwell and A.K. Behrensmeyer (Editors), Taphonomic Approaches to Time Resolution in Fossil Assemblages. Paleontological Society Short Courses in Paleontology, 6: 57-78. Burnham, R.J. and Spicer, R.A., 1986. Forest litter preserved by volcanic activity at El Chicón, Mexico: a potentially accurate record of the pre-eruption vegetation. Palaios, 1: 158-161. Burnham, R.J. and Wing, S.L., 1992. The reflection of deciduous forest communities in leaf litter: implications for autochthonous litter assemblage from the fossil record. Paleobiology, 18: 30-49. Burnham, R.J., Pitman, N.C, Johnson, K.R. and Wilf P., 2001. Habitat-related error in estimating temperatures from leaf margins in a humid tropical forest. American Journal of Botany, 88: 1096-1102. Clark, W.B. and Bibbins A.B., 1897. The stratigraphy of the Potomac Group in Maryland. Journal of Geology, 5: 479-506. Cobban, W.A. and Merewether, E.A., 1983. Stratigraphy and paleontology of midCretaceous rocks in Minnesota and contiguous areas. Washington Alexandia, VA, U.S. Geological Survey. Geological Survey Professional Paper, 53 pp. Crane, P.R. and Dilcher, D.L., 1984. Lesqueria : an early angiosperm fruiting axis from the mid-Cretaceous. Annals of Missouri Botanical Garden, 71(2): 384-402. Crane, P.R., Manchester, S.R. and Dilcher D.L., 1990. A preliminary survey of fossil leaves and well-preserved reproductive structures from the Sentinel Butte Formation (Paleocene) near Almont, North Dakota. Fieldiana Geology News Series, 20: 1-63. Dilcher, D.L., 1974. Approaches to the iden tification of angiosperm leaf remains. Botanical Review, 40: 1-157. Dilcher, D.L., 1979. Early angiosperm reproduction: an introductory report. Review of Palaeobotany and Palynology, 27: 291-328. Dilcher, D.L., 1984. In search of fossil plants. Terra, 1: 10-15.

PAGE 390

382 Dilcher, D.L., 2000. Toward a new synthesis: major evolutionary trends in the angiosperm fossil record. PNAS, 97(13): 7030-7036. Dilcher, D.L., 2001. A new synthesis for angiosperm phylogeny. The Advanced Study of Prehistory Life and Geology of Junggar Basin, Xinjiang, China: Proceedings of the Sino-Germany symposium on prehistory life and Geology of Junggar Basin, Xingjiang. Urumqi, 2001: 65-75. Dilcher, D.L. and Basson, P., 1990. Mid-Cretace ous angiosperm leaves from a new fossil locality in Lebanon. Botanical Gazette, 151: 538-547. Dilcher, D.L. and Crane, P.R., 1984a. Archaeanthus : an early angiosperm from the Cenomanian of the Western Interior of No rth America. Annals Missouri Botanical Garden, 71(2): 351-383. Dilcher, D.L. and Crane, P.R., 1984b. In pursuit of the first flowers. Natural History Magazine, 93: 56-61. Dilcher, D.L. and Farley, M.B., 1988. Cenomanian miospores and co-occurring megafossils in the mid-continent of north America. 7th International Palynological Congress, Brisbane, Abstract, p.39. Dilcher, D.L. and Kovach, W.L., 1986. Early angiosperm reproduction: A new fructification from the Dakota Formation (C enomanian) of Kansas. American Journal of Botany, 73: 1228-1235. Dilcher, D.L., Crepet, W.L., Beeker, C.D. and Reynolds, H.C., 1976. Reproductive and vegetative morphology of a Cretaceous angiosperm. Science, 191: 854-856. Dilcher, D.L., Potter, F.W., and Reynolds H.C., 1978. Preliminary account of middle Cretaceous angiosperm remains from interior of North America. Courier Forschungslnstitüt Senckenberg, 30: 9-15. Doyle, J.A., 1992. Revised palynological corre lations of the lower Potomac Group (USA) and the Cocobeach sequence of Gabon (Barremian-Aptian). Cretaceous Research, 13: 337-349. Doyle, J.A. and Hickey, L.J., 1976. Pollen and leaves from the mid-Cretaceous Potomac Group and their bearing on early angiosperm evolution. In: C.B. Beck (Editor), Origin and Early Evolution of Angiosperms. Columbia University Press, New York, N.Y., pp. 139-206. Doyle, J.A. and Robins, E.I., 1977. Angiosperm pollen zonation of the continental Cretaceous of the Atlantic coastal plain and its application to deep wells in the Salisbury embayment. Palynology, 1: 43-78.

PAGE 391

383 Eicher, D.L., 1965. Foraminifera and biostratig raphy of the Graneros Shale. Journal of Paleontology, 39: 875-909. Emiliani, C., 1961. The temperature decrease of surface seawater in high latitudes and of abyssal-hadal water in open oceanic basins during the past 75 million years. Deep Sea Research, 8: 144-147. Farley, M.B. and Dilcher, D.L., 1986. Correlation between miospores and depositional environments of the Dakota formation (mid-Cretaceous) of north central Kansas and adjacent Nebraska. Palynology, 10: 117-133. Fassell, M.L. and Bralower, T.J., 1999. Warm, equitable mid-Cretaceous: stable isotope evidence. In: E. Barrera and C.C. Johnson (Editors), Evolution of the Cretaceous Ocean-Climate System. Geological Society of America Special Paper, 232: 121-142. Ferguson, D.K., 1985. The origin of leaf assemblage: new light on an old problem. Review of Palaeobotany and Palynology, 46: 117-188. Fontaine, W.M., 1889. The Potomac or Younger Mesozoic Flora. U.S. Geological Survey Monograph, 15:1-377. Frakes, L.A. and Francis, J.E., 1988. A guide to Phanerozoic cold polar climates from high-latitude ice rafting in the Cretaceous. Nature, 333: 547-549. Franks, P.C., 1966. Petrology and stratigraphy of the Kiowa and Dakota Formation (basal Cretaceous), north central Kansas. Ph. D. thesis, Department of Geology, University of Kansas, 312 pp. Franks, P.C., 1975. The transgressive-regressive sequence of the Cretaceous Cheyenne, Kiowa, and Dakota formations of Kansas. In: W.G.E. Caldwell (Editor), The Cretaceous System in the Western Interior of North America. Geological Association of Canada Special Paper, 13: 469-521. Frye, J.C., Willman, H.B. and Glass, H.D., 1964. Cretaceous deposits and the Illinoian glacial boundary in western Illinois. I llinois State Geological Survey, 364: 1-28. Gastaldo, R.A., 1989. Preliminary observations on phytotaphonomic assemblages in a subtropical/temperate Holocene boyhood delta: Mobile Delta, Gulf Coastal Plain, Alabama. Review of Palae obotany and Palynology, 58: 61-83. Gastaldo, R.A., 1992. Taphonomic considerations for plant evolutionary investigations. Paleobotanists, 41: 211-223.

PAGE 392

384 Gastaldo, R.A., Bearce, S.C., Degges, C.W., Hunt, R.J., Peebles M.W. and Violette, D.L., 1989. Biostratinomy of a Holocene oxbow lake: a backswamp to mid-channel transect. Palaeogeography, Palaeoclimatology, Palaeoecology, 58: 47-59. Givnish, T.J., 1987. Comparative studies of leaf form: assessing the relative roles of selective pressures and phylogenetic cons traints. New Phytologist, 106 (Suppl.): 131160. Habicht, J.K.A., 1979. Paleoclimate, paleomagnetism, and continental drift. American Association of Petroleum Geology, 9: 1-31. Hall, J.W., 1963. Megaspores and other fossils in the Dakota Formation (Cenomanian) of Iowa, USA. Pollen et Spores, 5: 425-443. Hambrey, H.A. and Harland, W.B., 1981. Summary of earth's pre-Pleistocene glacial record. In: H.A. Hambrey and W.B. Harland (Editors). Earth's Pre-Pleistocene Glacial Record. Cambridge University Press, Cambridge, pp. 943-969. Hamilton, V.J., 1989. Stratigraphic sequences and hydrostratigraphic units in Lower Cretaceous strata in Kansas. Mater thesis, Geology Department, Colorado School of Mines, Golden, 165 pp. Hamilton, V.J., 1994. Sequence stratigraphy of Cretaceous Albian and Cenomanian strata in Kansas. In G.W. Shurr, G.A. Ludvigson and R.H. Hammond (Editors), Perspectives on the Eastern Margin of the Cretaceous Western Interior Basin. Geological Society of Ameri ca Special Paper, 287: 79-96. Hammer, ., Harper, D.A.T. and Ryan, P.D., 2001. PAST: Paleontological statistics software package for education and data analysis. Paleontologia Electronica, 4(1): 19. Hattin, D.L., 1965. Stratigraphy of the Graneros Shale (Upper Cretaceous) in central Kansas. Kansas Geological Survey Bulletin, 178: 1-83. Hattin, D.L., 1967. Stratigraphic and paleoecol ogical significance of macroinvertebrate fossils in the Dakota Formation (Upper Cretaceous) of Kansas. In: C. Teichert and W.L. Yochelson (Editors), Essays in Paleontology and Stratigraphy. University of Kansas Department of Geology Special Paper, 2: 570-589. Heer, O., 1868. Die fossile Flora der Polarla nder. Flora Fossilis Arctica, Band 1: 1-192. Heer, O., 1869. Flora fossilis alaskana. Flora Fossilis Arctica, Band 2 (2): 1-41. Heer, O., 1882. Die Flora der Komeschichter and Die Flora der Ataneschichten. Flora Fossilis Arctica, Band 6 (2): 1-112.

PAGE 393

385 Heer, O., 1883. Die fossile Flora der Polarander. In Flora fossilis Arctica, Band 7: 1-275. Hickey, L.J., 1971. Evolutionary significance of leaf architectural features in the woody dicots. American Journal of Botany, 58: 469 (abstract). Hickey, L.J., 1973. Classification of the arch itecture of dicotyledonous leaves. American Journal of Botany, 60: 17-33. Hickey, L.J., 1979. A revised classification of the architecture of dicotyledonous leaves. In: C.R. Metcalfe and L. Chalk (Editors), Anatomy of the Dicotyledons: Systematic Anatomy of the Leaf and Stem, with a Brie f History of the Subject. Clarendon Press, Oxford, pp. 25-39. Hickey, L.J. and Doyle J.A., 1977. Early Cretaceous evidence for angiosperm evolution. Botanical Review (Lancaster), 43(1): 3-104. Huang, Q.C., 1989. The Cheyenne sandstone and Cheyenne flora from the upper Lower Cretaceous (Albian) from southwestern Kansas. Unpublished Mater thesis, Geology Department, Indiana University, Bloomington, Indiana, pp. 1-112. Hughes, N.F., 1976. Palaeobiology of angiosperm origins. Cambridge University Press, Cambridge. 242 pp. Hurlbert, S.H., 1971. The non-concept of species diversity: a critique and alternative parameters. Ecology, 52: 577-586. IAPT (International Association for Plant Taxonomy), 2001. International Code of Botanical Nomenclature (St. Louis Code). http://www.bgbm.fuberlin.de/iapt/nomenclature/code/SaintLouis/0000St.Luistitle.htm . 04/19/2002. Joekel, R.M., 1987. Paleogeomorphic significance of two paleosols in the Dakota Formation (Cretaceous), southeastern Nebraska. University of Wyoming Contributions to Geology 25(2): 95-102. Joekel, R.M., 1991. Deeply developed plinthic paleosols in the Dakota Formation (Albian?, Cenomanian), southeastern Nebraska: evidence from warm, wet paleoclimate and regional geomorphic stability. Geological Society of America, Abstract with Programs, 23: A40. Karl, H.A., 1976. Depositional history of Da kota Formation (Cretaceous) sandstone, southeastern Nebraska. Journal of Sedimentary Petrology, 46: 124-131. Kauffman, E.G., 1977. Geological and biological overview: Western Interior Cretaceous basin. The Mountain Geologist, 14: 75-99.

PAGE 394

386 Kauffman, E.G. and Ryer, T.A., 1980. Paleobiologic evidence for Cretaceous tides, Western Interior Basin, North America. American Association of Petroleum Geologists Bulletin, 64(5): 731. Kempton, R.A., 1979. Structure of species abundance and measurement of diversity. Biometrics, 35: 307-322. Kershaw, K.A. and Looney, J.H.H., 1985. Quantitative and dynamic plant ecology. Edward Arnold, London. 282 pp. Kovach, W.L., 1987. Dispersed plant remains from the Cenomanian of Kansas: systematic and paleoecologic approaches. Unpublished Ph. D. thesis, Geology Department, Indiana University, Bloomington, Indiana. 242 pp. Kovach, W.L. and Dilcher, D.L., 1985. A new combination of Paxillitriletes (fossil megaspores). Taxon, 34: 297. Kovach, W.L. and Dilcher, D.L., 1988. Megaspores and other dispersed plant remains from the Dakota Formation (Cenomanian) of Kansas. Palynology, 12: 89-119. Krassilov, V.A., 1973. Climatic changes in eastern Asia as indicated by fossil floras, I, Early Cretaceous. Paleogeography, Paleoc limatology, and Paleoecology, 13: 261-273. Krassilov, V.A., 1981. Changes of Mesozoic vegetation and the extinction of dinosaurs. Paleogeography, Paleoclimatology, and Paleoecology, 34: 207-224. Kvacek, J. and Dilcher, D.L., 2000. Comparison of Cenomanian Floras from Western Interior, North America and Central Europe. Acta Universitatis Carolinae-Geologica, 44(1): 7-38. Larson, R.L., 1991. Latest pulse of the Earth: evidence for a mid-Cretaceous super plume. Geology, 19: 547-550. LAWG (Leaf Architecture Working Group), 1999. Manual of leaf architectureMorphological description and categorization of dicotyledonous and net-veined monocotyledonous angiosperms. Smithsonian Institution, Washington, DC. 65 pp. Lesquereux, L., 1868a . Fossil plants from Rock Creek. In: F.V. Hayden (Editor), Notes on the Lignite Deposits of the West. American Journal of Science, 45: 205-208. Lesquereux, L., 1868b . On some Cretaceous fossil plants from Nebraska. American Journal of Science, 46: 91-105. Lesquereux, L., 1872. Enumeration and description of the fossil plants from the specimens obtained in the explorations of Dr. F.V. Hayden, 1870 and 1871: II.

PAGE 395

387 Remarks on the Cretaceous species described above. U.S Geological and Geographical Survey Territory Annual Report, 1871: 283-318. Lesquereux, L., 1873. Enumeration and Description of the Fossil Plants from the Specimens Obtained in the Explorations of Dr. F.V. Hayden, 1870 and 1871: II. Remarks on the Cretaceous species descri bed above. Geological and Geographical Survey Territory Annual Report, 1872: 371-427. Lesquereux, L., 1874. Contributions to the fossil flora of the Western Territories-I, the Cretaceous Flora. U.S. Geological Survey Territory Report, 6: 1-136. Lesquereux, L., 1876a . New species of fossil plants from the Cretaceous formations of the Dakota Group. U.S. Geological Survey Territory Bulletin, 1: 391-400. Lesquereux, L., 1876b . On the Tertiary Flora of the North American lignite considered as evidence of the age of the formation. U.S. Geological and Geographical Survey Territory Annual Report, 1874: 273-315. Lesquereux, L., 1876c . Review of the Cretaceous Flor a of North America. Geological and Geographical Survey Territory Annual Report, 1874: 316-365. Lesquereux, L., 1878. Remarks on specimens of Cretaceous and Tertiary plants secured by the survey in 1877-with a list of species hitherto described. In: F.V. Hayden (Editor), Tenth Annual Report of the United States Geological and Geographical Survey of the Territories. Lesquereux, L., 1883. Contributions to the fossil flora of the Western Territories, Part 3. The Cretaceous and Tertiary floras. U.S. Geological Survey of Territories, 8: 2-108. Lesquereux, L., 1892. The flora of the Dakota Group. U.S. Geological Survey Monography 17. 400 pp. Lidgard, S. and Crane, P.R., 1988. Quantitative analyses of the early angiosperm radiation. Nature, 331: 344-346. Lidgard, S. and Crane, P.R., 1990. Angiosperm diversification and Cretaceous floristic trends: a comparison of palynofloras and leaf macrofloras. Paleobiology, 16: 77-93. Liu, Y. and Gastaldo, R.A., 1992. Characters a nd provenance of log-transported gravels in a carboniferous channel deposit. Jour nal of Sedimentary Petrology, 62: 1072-1083. Loeblich, A.R. and Tappan, H., 1961. Cretaceous planktic foraminifera: Part 1, Cenomanian. Micropaleonlogy. 7: 257-305. Ludvigson, G.A., Brenner, R. and Dogan A., 1987. Preliminary evaluation of the provenance and diagenetic environments of Dakota Formation sandstones in

PAGE 396

388 northwest Iowa. Geological Society of Am erica, Abstract with Programs, 19: 231232. Macfarlane, P.A., Whittemore, D.O., Townsend, M.A., Doveton, J.H., Hamilton, V.J., Coyle III, W.G., Wade, A., Macpherson, G.L. and Black, R.D., 1990. The Dakota aquifer program: annual report, FY89: Kansas Geological Survey, Open-file Report 90-27. 301 pp. Magurran, A.E., 1988. Ecological Diversity and Its Measurement. Princeton University Press, New Jersey. 192 pp. Martin, C.E. and von Willert, D.J., 2000. Leaf epidermal hydathodes and the ecophysiological consequences of foliar water uptake in species of Crassula from the Namib Desert in Southern Africa. Plant Biology, 2: 229-242. Meek, M.B. and Hayden, F.V., 1858. Remarks on the Lower Cretaceous beds of Kansas and Nebraska, together with descriptions of some new species of Carboniferous fossils from the valley of the Kansas river. Proceedings of the National Academy of Sciences, 10: 256-266. Meldahl K.H., Scott, D. and Carney K., 1995. Autochthonous leaf assemblages as record of deciduous forest communities: an actualistic study. Lethaia, 28: 383-394. Munter, J.A., Ludvigson, G.A. and Bunker B.J., 1983. Hydrogeology and stratigraphy of the Dakota Formation in northwest Iowa. Iowa Geological Survey Water Supply Bulletin 13. 55 pp. Mutterlose, J., 1992. Biostratigraphy and paleobiogeography of Early Cretaceous calcareous nannofossils. Cretaceous Research, 18: 167-189. Nathorst, A.G., 1911. On the value of fossil floras of the Arctic regions as evidence of geological climates. Geology Magazine, 8: 217-225. Newberry, J.S., 1868. Notes on the later extinct floras of North America, with descriptions of some new species of fossil plants from the Cretaceous and Tertiary strata. New York Lyc. Nat. Hist. Annals, 9: 1-76. Newberry, J.S., 1886. The Flora of Amboy Clays. Bulletin of the Torrey Botanical Club, 13: 33-37. Newberry, J.S., 1895. The Flora of Amboy Clays. U.S. Geological Survey Monograph 26: 1-137. Newberry, J.S., 1898. The later extinct floras of North America. U.S. Geological Survey Monograph, 35: 1-295.

PAGE 397

389 Norris, R.D. and Wilson, P.A., 1998. Low-latitude sea-surface temperatures for the midCretaceous and the evolution of pla nktonic foraminifera. Geology, 26: 823-826. Parham, W.E., 1970. Clay mineralogy and geology of Minnesota's kaolin clays. Minnesota Geological Survey Special Publication, 10: 1-142. Parham, W.E. and Hogberg, R.K., 1964. Kaolin clay resources of the Minnesota River Valley, Brown, Redwood and Renville Counties, a preliminary report. Minnesota Geological Survey Report of Investigations, 3: 1-43. Parrish, J.T. and Spicer, R.A., 1988. Middl e Cretaceous wood from the Nanushuk Group, central north slope, Alaska. Paleontology, 31: 19-34. Peet, R.K., 1974. The measurement of species diversity. Annual Review of Ecology and Systematics, 5: 285-307. Pianka, E.R., 1966. Latitudinal gradients in species diversity: A reviews of concepts. American Naturalist, 100: 33-34. Pierce, R.L., 1961. Lower Upper Cretaceous plant microfossils from Minnesota. Minnesota Geological Survey, 42: 1-86. Plummer, N.V. and Romary, J.F., 1942. Stratigraphy of the Pre-Greenhorn Cretaceous beds of Kansas. Kansas Geological Survey Bulletin, 41: 313-348. Raup, D.M., 1972. Taxonomic diversity during the Phanerozoic. Science, 177: 10651071. Raup, D.M., 1975. Taxonomic diversity estimation using rarefaction. Paleobiology, 1(4): 333-342. Raup, D.M., Gould, S.J., Schopf, G.M. and Simb erloff, D.S., 1973. Stochastic models of phylogeny and the evolution of diversity. Journal of Geology, 81: 525-542. Ravn, R.L. and Witzke, B.J., 1994. The Mid-Cretaceous boundary in the Western Interior Seaway, central United States: Implications of palynostratigraphy from the type Dakota Formation. In: G.W. Shurr, G.A. Ludvigson and R.H. Hammond (Editors), Perspectives on the Eastern Margin of the Cretaceous Western Interior Basin. Boulder, Colorado, Geological Society of America Special Paper. pp. 111-128. Ravn, R.L. and Witzke, B.J., 1995. The palynostratigraphy of the Dakota Formation (?late Albian to Cenomanian) in its type area, northwestern Iowa and northeastern Nebraska, USA. Paleontographica Abt. B, 234: 93-171.

PAGE 398

390 Retallack, G. and Dilcher, D.L., 1981a. A coastal theory of flowering plant origin. In: K.J. Niklas (Editor), Paleobotany, Paleoecology, and Evolution. Praeger Publishers, New York. pp. 27-77. Retallack, G. and Dilcher, D.L., 1981b. Early angiosperm reproduction: Prisca reynoldsii gen. et sp. nov. from Mid-Cretaceous coastal deposits in Kansas, USA. Palaeontographica, Abst. B 179: 103-137. Retallack, G. and Dilcher, D.L., 1986. Cr etaceous angiosperm invasion of North America. Cretaceous Research, 7: 227-252. Roberts, L.R.N, and Kirschbaum, M.A., 1995. Paleogeography of the Late Cretaceous of the western interior of middle North Am erica: coal distribution and sediment accumulation. U.S. Geological Survey Professional Paper, 1561: 1-115. Rushforth, S.R., 1971. A flora from the Dakota Sandstone Formation (Cenomanian) near Westwater, Grand County, Utah. Brigham Young University Science Bulletin Biological Series, 14: 1-44. Ryer, T.A. and Kauffman, E.G., 1980. Physical evidence for Cretaceous tides, Western Interior Basin, North America. American Association of Petroleum Geologists Bulletin, 64: 778-779. Sanders, H.L., 1968. Marine benthic diversity: a comparative study. American Naturalist, 102: 243-282. Savin, S.M., 1977. The history of the earth's surface temperature during the past 100 million years. Annual Review Earth and Planetary Sciences, 5: 319-355. Schemel, M.P., 1950. Cretaceous plant microfossils from Iowa. American Journal of Botany, 37: 750-754. Schlanger, S.O., Jenkyns, H.C. and Premoli-Silva, I., 1981. Volcanism and vertical tectonics in the Pacific basin related to global Cretaceous transgression. Earth and Planetary Science Letters, 52: 435-449. Schwarzwalder, R. N. J. 1986. Systematics and early evolution of the Platanaceae. Ph. D. thesis, Department of Biology, Indiana University. 198 pp. Schwarzwalder, R.N. and Dilcher, D.L., 1981. Platanoid leaves and infructescences from the Cenomanian of Kansas (Abstract). Botanical Society of America, Miscellaneous Publication 160: 47. Schwarzwalder, R.N. and Dilcher, D.L., 1991. Systematic placement of Platanaceae in the Hamamelidae. Ann. Missouri Bot. Gard., 78: 962-969.

PAGE 399

391 Scott, R.W., Franks, P.C., Evetts, M.J., Bergen, J.A. and Stein, J.A., 1998. Timing of mid-Cretaceous relative sea level changes in the Western Interior: Amoco No. 1 Bounds Core. In: W.E. Dean and M.A. Arthur (Editors), Stratigraphy and Paleoenvironments of the Cretaceous Western Interior Seaway, USA: SEPM, Concepts in Sedimentology and Paleontology, 6: 11-34. Setterholm, D.R., 1994. The cretaceous rocks of southwestern Minnesota: Reconstruction of a marine to nonmarine transition along the eastern margin of the western Interior Seaway. In: G.W. Shurr, G.A. Ludvigson, and R.H. Hammond (Editors), Perspectives on the Eastern Margin of the Cretaceous Western Interior basin. Boulder, Colorado, Geological Society of America Special Paper. pp. 97-110. Siemers, C.T., 1971. Stratigraphy, paleoecology, and environmental analysis of the upper part of the Dakota Formation (Cretaceous), Central Kansas. Ph. D. thesis, Department of Geology, Bloomington, Indiana University. 287 pp. Siemers, C.T., 1976. Sedimentology of the Rocktown Channel Sandstone, upper part of the Dakota Formation (Cretaceous), central Kansas. Journal of Sedimentary Petrology, 46(1): 97-123. Skog, J.E. and. Dilcher, D.L., 1992. A new species of Marsilea from the Dakota Formation in central Kansas. American Journal of Botany, 79: 982-988. Skog, J.E. and Dilcher, D.L., 1994. Lower vascular plants of the Dakota Formation in Kansas and Nebraska. Review of Paleobotany and Palynology, 80: 1-18. Skog, J.E., Dilcher, D.L. and Potter, F.W., 1992. A new species of Isoetites from the midCretaceous Dakota Group of Kansas and Nebr aska. American Fern Journal, 82: 151161. Smiley, C.J., 1967. Paleoclimatic interpretations of some Mesozoic floral sequences. American Association of Petrol eum Geologists Bulletin, 51: 849-863. Spicer, R.A., 1989. The formation and interpretation of plant fossil assemblages. In: J.A. Callow (Editor), Advances in Botanical Research, 16: 95-191. Spicer, R.A. and Parrish, J.T., 1986. Paleobotanical evidence for cool north polar climates in middle Cretaceous (Albian-Cenomanian) time. Geology, 14: 703-706. Stevens, G.C., 1989. The latitudinal gradient in geographical range: How so many species coexist in the tropics. American Naturalist, 133: 240-256. Stevens, P.F., 2001 (onwards). Angiosperm Phylogeny Website. http://www.mobot.org/MOBOT/research/APweb . 04/18/2002.

PAGE 400

392 Taylor, B.J., 1972. Stratigraphic correlation in southeast Alexander Island. In: R. Adie (Editor), Antarctic Geology and Geophysics. Oslo, Universitetsforlaget. pp. 149-153. Tester, A.C., 1931. The Dakota Stage of the t ype locality. Iowa Geological Survey, 35: 199-332. Tiffney, B.H. and Niklas, K.J., 1990. Continen tal area, dispersion, latitudinal distribution and topographic variety: A test of correlation with terrestrial plant diversity. In: W.D. Allmon and R.M. Ross (Editors), Causes of Evolution: A Paleontological Perspective, University of Chicago Press, Chicago. pp. 76-102. Tschudy, R.H., 1981. Geographic distribution and dispersal of Normapolles genera in North America. Review of Pa leobotany and Palynology, 35: 283-314. Upchurch, G.R. and Dilcher, D.L., 1990. Cenomanian angiosperm leaf megafossils, Dakota Formation, Rose Creek I locality, Jefferson County, southeastern Nebraska. Denver, Department of the Interior U.S. Geological Survey Bulletin 1915. 55 pp. Upchurch, G.R., Crane, P.R., Drinnan A.N., 1994. The megaflora from the Quantico Locality (Upper Albian), Lower Cretaceous Potomac Group of Virginia. Virginia Museum of natural History Memoir, 4: 1-57. USGS, 2001. National Geologic Map Database (GEOLEX). http://ngmdb.usgs.gov/Geolex/geolex_qs.html . 04/19/2002. Vakhrameev, V.A., 1964. Jurassic and Early Cretaceous floras of Eurasia and the paleofloristic provinces of this period. Trans. Geol. Inst., 102: 1-126 (in Russian). Vakhrameev, V.A., 1975. Main features of phytogeography of the globe in Jurassic and Early Cretaceous time. Paleontology Journal, 2: 247-255. Vakhrameev, V.A. and Hughes, N.F. 1991. Jura ssic and Cretaceous floras and climates of the earth. Cambridge University Press, Cambridge, New York. 318 pp. Wang, H.S., Dilcher, D.L. and Schwarzwalder, R.N., 2000. Eoplatanus serrata -an extinct Cretaceous sycamore or plane tree from Braun Locality, Kansas, USA. The sixth conference of International Organization of Paleobotany, Qinhuangdao, China. (Abstract) Ward, J.V., 1986. Early Cretaceous angiosperm pollen from the Cheyenne and Kiowa formations (Albian) of Kansas, U.S. Palaeontographica, Abteilung B, 202: 1-50. Watson, L. and Dallwitz, M.J., 1992(onwards). http://biodiversity.uno.edu/delta/angio/index.htm . 04/18/2002.

PAGE 401

393 White, C.A., 1870. Report of the geological survey of the state of Iowa. American Journal of Science, 1: 1-381. Whitley, D.L. 1980. A stratigraphic and sedimentologic analysis of Cretaceous rocks in northwest Iowa. Master thesis, Geology Depa rtment, University of Iowa, Iowa City. 81 pp. Whitley, D.L. and Brenner, R.L., 1981. Subsurface stratigraphic and sedimentologic analyses of Cretaceous rocks in Northwest Iowa. Cretaceous stratigraphy and sedimentation in northwest Iowa, northeas t Nebraska, and southeast South Dakota: Iowa Geological Survey, Guide Book series, 4: 57-75. Wilf, P., 1997. When are leaves good thermometers? A new case for leaf margin analysis. Paleobiology, 23: 373-390. Wilf, P., 1998. Using fossil plants to understand global change: evidence for PaleoceneEocene warming in the greater Green River Basin of southwestern Wyoming. Ph. D. thesis, Department of Geology, University of Pennsylvania, Philadelphia. 384 pp. Wilf, P. and Wing, S.L., 1998. Using fossil leaves as paleoprecipitation indicators: an Eocene example. Geology, 26: 203-206. Wilf, P., Wing, S.L., Greenwood, D.R. and Greenwood C.L., 1999. Using fossil leaves as paleoprecipitation indicators: an Eo cene example, Reply. Geology, 27: 92. Wilson, P.A., Jenkyns, H.C. and Norris R.D., 1999. Death in the Tropics for Cretaceous Atolls: warm sea surface temperatures caught holding the smoking gun?. Journal of Conference Abstracts (11th Bathurst Meeting). http://www.campublic.co.uk/science/publications/JConfAbs/4/982.html . 04/18/2002. Wilson, P.A., Jenkyns, H.C., Elderfield, H. and Larson, R.L., 1998. The paradox of drowned carbonate platforms and the origin of Cretaceous Pacific guyots. Nature, 392: 889-894. Witzke, B.J. and Ludvigson, G.A., 1982. Cretaceous stratigraphy and depositional systems in Guthrie County, Iowa, Geological Society of Iowa. Field Trip Guidebook 38. 46 pp. Witzke, B.J. and Ludvigson, G.A., 1994. The Dakota Formation in Iowa and the type area. In: G.W. Shurr, G.A. Ludvigson and R.H. Hammond (Editors), Perspectives on the Eastern Margin of the Cretaceous Western Interior basin. Boulder, Colorado, Geological Society of America Special Paper. pp. 43-78. Witzke, B.J. and Ludvigson, G.A., 1996. Mid-Cr etaceous fluvial deposits of the Eastern Margin, Western Interior Basin: Nishna botna Member, Dakota Formation-a field

PAGE 402

394 guide to the Cretaceous of Guthrie Count y. Geological Society Guide Book series 17. 75 pp. Witzke, B.J., Ludvigson, G.A., Poppe, J.R. and Ravn, R.L., 1983. Cretaceous paleogeography along the eastern margin of the Western Interior Seaway, Iowa, southern Minnesota, and eastern Nebraska and South Dakota. In: M.W. Reynolds and E.D. Dolly (Editors), Mesozoic Paleogeography of West-central United States. Denver, Society of Economic Paleontologi sts and Mineralogists, Rocky Mountain Section. pp. 225-252. Wolfe, J.A., 1972. Significance of comparative foliar morphology to paleobotany and neobotany. American Journal of Botany, 59(664) (abstract). Wolfe, J.A., 1973. Fossil forms of Amentiferae. Brittonia, 25(4): 334-355. Wolfe, J.A., 1979. Temperature parameters of humid to mesic forests of eastern Asia and relation to forests of other regions in the Northern Hemisphere and Australasia. U.S. Geological Survey Professional Paper, 1106: 1-37. Wolfe, J.A., 1993. A method of obtaining climatic parameters from leaf assemblages. U.S. Geological Survey Bulletin 1579. pp. 1-71. Wolfe, J.A., Doyle, J.A. and Page, V.M., 1975. The bases of angiosperm phylogeny: paleobotany. Annals of the Missouri Botanical Garden, 62(3): 801-824. Wolfe, J.A. and Wehr, W., 1987. Middle Eocene dicotyledons plants from Republic, northeastern Washington. U.S. Geological Survey Bulletin 1579, 61(1): 33-77. Zeller, D.E., 1968. The stratigraphic succession in Kansas. Bulletin of the Kansas Geological Survey, 189: 1-81.

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395 BIOGRAPHICAL SKETCH Hongshan Wang was born in 1966 in Henan Province, central China. He received his Bachelor of Science degree in Geol ogy from the Department of Geology, Lanzhou University, Gansu Province, China, in 1988. He then worked in the Petroleum School of Shengli Oilfield, Dongying City, Shandong Province, as a lecturer for three years. He was admitted to the Graduate School of China University of Geosciences (Beijing) in 1991. He received his Master of Scien ce degree in Paleontology and Stratigraphy on June 1994 with honors. After his graduation, he worked as a field geologist in the Beijing Geological Institute, Beijing Municipality for half a year and as the Director of Beijing Central Laboratory of the Ministry of Geology and Mineral Resources (Beijing) for a year and half. He moved to Gainesville, Florida, USA in 1996 to pursue a Ph.D. degree in the Department of Geological Sciences at the University of Florida under the direction of Professor David L. Dilcher. He is now a member of the Paleobotanical Society of China, the Paleontological Society of China, the Botanical Society of America (Paleobotanical section), and the Geological Society of America.