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Palynological changes across the Cretaceous-Tertiary boundary in Colombia, South America

Permanent Link: http://ufdc.ufl.edu/UFE0024565/00001

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Title: Palynological changes across the Cretaceous-Tertiary boundary in Colombia, South America
Physical Description: 1 online resource (105 p.)
Language: english
Creator: De La Parra, German
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: colombia, diversity, kt, palynology, taxonomic
Geological Sciences -- Dissertations, Academic -- UF
Genre: Geology thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: PALYNOLOGICAL CHANGES ACROSS THE CRETACEOUS-TERTIARY BOUNDARY IN COLOMBIA, SOUTH AMERICA The Cretaceous-Tertiary boundary (KT boundary) event is recognized as one of the major environmental crises of earth history. It is associated with significant extinctions of many groups. The palynological record from mid latitudes shows a dramatic and abrupt disappearance of many dominant taxa including the Late Cretaceous angiosperms at this boundary. An estimated loss of ~17-30% of palynomorph species has been seen throughout the western interior of North America, however not a single section has been studied palynologically in detail from the tropics and the effect of the KT boundary event on the vegetation of tropical low latitudes is not known. Were extinction percentages of tropical low latitude vegetation greater than in middle latitude temperate communities? Did the palynofloral diversity change as a consequence of the KT boundary extinction event? To address these two questions, I studied 81 palynological samples across the KT boundary of a stratigraphic section in Cesar-Rancheria basin, Colombia, northern South America. Several techniques, including range through method, rarefaction, per-capita extinction and origination rates, and measures of taxonomic diversity were used to estimate extinction percentages and the changes in diversity associated with the boundary in low latitude tropical environments. There is extinction percentage of 48-70% associated with the KT boundary and a significant change in the rate of extinction. Origination rates do not seem to be affected. The analysis show a high diversity Cretaceous palynoflora suddenly replaced by a low diversity association that dominated during the Paleocene. The results suggest important changes in neotropical floras across the KP boundary, far more intense than in temperate regions.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by German De La Parra.
Thesis: Thesis (M.S.)--University of Florida, 2009.
Local: Adviser: Dilcher, David L.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2011-05-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0024565:00001

Permanent Link: http://ufdc.ufl.edu/UFE0024565/00001

Material Information

Title: Palynological changes across the Cretaceous-Tertiary boundary in Colombia, South America
Physical Description: 1 online resource (105 p.)
Language: english
Creator: De La Parra, German
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: colombia, diversity, kt, palynology, taxonomic
Geological Sciences -- Dissertations, Academic -- UF
Genre: Geology thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: PALYNOLOGICAL CHANGES ACROSS THE CRETACEOUS-TERTIARY BOUNDARY IN COLOMBIA, SOUTH AMERICA The Cretaceous-Tertiary boundary (KT boundary) event is recognized as one of the major environmental crises of earth history. It is associated with significant extinctions of many groups. The palynological record from mid latitudes shows a dramatic and abrupt disappearance of many dominant taxa including the Late Cretaceous angiosperms at this boundary. An estimated loss of ~17-30% of palynomorph species has been seen throughout the western interior of North America, however not a single section has been studied palynologically in detail from the tropics and the effect of the KT boundary event on the vegetation of tropical low latitudes is not known. Were extinction percentages of tropical low latitude vegetation greater than in middle latitude temperate communities? Did the palynofloral diversity change as a consequence of the KT boundary extinction event? To address these two questions, I studied 81 palynological samples across the KT boundary of a stratigraphic section in Cesar-Rancheria basin, Colombia, northern South America. Several techniques, including range through method, rarefaction, per-capita extinction and origination rates, and measures of taxonomic diversity were used to estimate extinction percentages and the changes in diversity associated with the boundary in low latitude tropical environments. There is extinction percentage of 48-70% associated with the KT boundary and a significant change in the rate of extinction. Origination rates do not seem to be affected. The analysis show a high diversity Cretaceous palynoflora suddenly replaced by a low diversity association that dominated during the Paleocene. The results suggest important changes in neotropical floras across the KP boundary, far more intense than in temperate regions.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by German De La Parra.
Thesis: Thesis (M.S.)--University of Florida, 2009.
Local: Adviser: Dilcher, David L.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2011-05-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0024565:00001


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1 PALYNOLOGICAL CHANGES ACROSS THE CRETACEOUS-TERTIARY BOUNDARY IN COLOMBIA, SOUTH AMERICA By FELIPE DE LA PARRA A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA

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2 2009 2009 Felipe de la Parra

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3 To my mom, Nicolas and Mariana

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4 TABLE OF CONTENTS page LIST OF TABLES................................................................................................................. .....6 LIST OF FIGURES................................................................................................................ ....7 ABSTRACT....................................................................................................................... ........9 CHAPTER 1 INTRODUCTION .............................................................................................................11 Previous Palynological Studies of the KT Boundary in Colo mbia .......................................15 Biostratigraphy of the KT Boundary in Colomb ia.............................................................. 17 2 OBJECTIVES................................................................................................................... .27 3 GEOLOGY AND STRATIGRAPHIC FRAMEWORK .....................................................28 Regional Geology..............................................................................................................2 8 Litostratigraphy and Depos itional Envir onment ..................................................................28 Molino Formation..............................................................................................................2 9 Barco Formation................................................................................................................ 29 4 MATERIALS.................................................................................................................... .33 5 METHODS ........................................................................................................................37 Diversity Pattern thr ough the KT Boundary ........................................................................ 37 Richness and Rarefaction...................................................................................................37 Shannon-Wiever Inde x ...................................................................................................... 38 Range Through Method ...................................................................................................... 38 Standing Diversity............................................................................................................. .39 Edge Effect and Piecewise Analysis ...................................................................................39 Graphic Correlation an d Taxonomic Rates ......................................................................... 40 Cluster Analysis............................................................................................................... ..42 Extinction Percentages.......................................................................................................43 6 RESULTS...................................................................................................................... ....46 Detecting the KT Bounda ry................................................................................................ 46 Magnetic Sus ceptibility .....................................................................................................48 Diversity Pattern Thr ough the KT Boundary ...................................................................... 50 Richness and Rarefaction...................................................................................................51 Shannon I ndex .................................................................................................................. .52 Standing Diversity............................................................................................................. .53

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5 Changes in Composition.....................................................................................................53 Taxonomic Rates................................................................................................................ 54 Extinction Percentages.......................................................................................................55 7 DISCUSSION................................................................................................................... .76 APPENDIX A PALYNOMORPH DISTRIBUTION IN SAMPLES FROM THE DIABLITO CORE .......85 B ILUSTRATION OF PALYNOMORPHS ...........................................................................93 LIST OF REFERENCES..........................................................................................................96 BIOGRAPHICAL SKETCH...................................................................................................105

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6 LIST OF TABLES Table page 1-1 Palynomorph species shared by the Di ablito and Sutataus a sections ..............................26 5-1 Equations to calculate mean standing diversity and per capita extinction (q) and origination (p) ra te.........................................................................................................45 6-1 Lithology of samples with high magnetic susceptib ility valu es......................................73 6-2 First (FAD) and Last (LAD) appearance datums for taxa used in the graphic correlation. ................................................................................................................. .74 6-3 Number of species per bin in each one of the Foote’s taxa categories. ............................75

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7 LIST OF FIGURES Figure page 1-1 Map showing the locations of the KT bounda ry sections with c ontinental record ...........24 1-2 Palynological zonation pr oposed by Germ eerad ............................................................24 1-3 Palynological zonation proposed by Muller ..................................................................25 1-4 Palynological zonation of the Cretaceous -Tertiary boundary interval in the ChecuaLenguazaque section......................................................................................................25 3-1 General stratigraphic column of Diablito .......................................................................31 3-2 Stratigraphic column of the interval where the KT boundary is locat ed..........................32 4-1 Location of Diab lito. ...................................................................................................... 36 5-1 Four fundamental classes of taxa present in each stratigraphic interval. .........................45 6-1 Stratigraphic distribution and a bundance of typical Cretaceous taxa. .............................57 6-2 Histogram of the number of LADs.................................................................................57 6-3 Graphic showing LAD and FAD of species that disappear between 1600’ and 1800’.....58 6-4 Histogram of the number of samples where the species with LAD between 1600’ and 1800’ were record ed. ..................................................................................................... 58 6-5 Magnetic susceptibility pattern found in five different sections of the KT boundary .......59 6-6 Magnetic susceptib ility in Di ablito ................................................................................60 6-7 Magnetic susceptibility of the KT boundary interval in Diab lito.. .................................. 61 6-8 Number of species (S) vs. Depth in Diablito ..................................................................61 6-9 Normal QQ plot of the mean number of species in the Cretaceous and the Paleocene....62 6-10 Rarified richne ss at 100 gr ains.. .....................................................................................63 6-11 Shannon index. ............................................................................................................ ..64 6-12 Normal QQ plot of the mean Shannon i ndex of the Cretaceous and the Paleocene.. .......65 6-13 Boxplot of the Shannon index for the Cretaceous and the Paleocene. .............................66 6.14 Standing diversity using range-through method. ............................................................67

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8 6-15 Standing diversity using range-thr ough method without singlet ons ................................68 6-16 Cluster analysis of the samples......................................................................................69 6-17 Graphic correlation. Diab lito vs. Rio Lo ro. ..................................................................70 6-18 Per capita origination rate..............................................................................................7 1 6-19 Per capita extinction rate ............................................................................................... 71 6-20 Presence-absence distribution chart of pollen and spores recorded in Diablito................72 6-21 Number of species in each of the K, KT and P categories. .............................................72 6-22 Number of species in each of the K, KT and P categories excluding singletones.. ..........73

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9 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science PALYNOLOGICAL CHANGES ACROSS THE CRETACEOUS-TERTIARY BOUNDARY IN COLOMBIA, SOUTH AMERICA By Felipe de la Parra May 2009 Chair: M.R.Perfit Major: Geology The Cretaceous-Tertiary boundary (KT boundary) event is recognized as one of the major environmental crises of earth history. It is associated with significant extinctions of many groups. The palynological record from mid latitudes shows a dramatic and abrupt disappearance of many dominant taxa including the Late Cretaceous angi osperms at this boundary. An estimated loss of ~17-30% of palynomorph species has been seen throughout the western interior of North America, however not a single s ection has been studied palynologically in detail from the tropics and the effect of the KT boundary event on the ve getation of tropical low latitudes is not known. Were extinction percentages of tropical low latit ude vegetation greater than in middle latitude temperate communities? Did the palynofloral dive rsity change as a consequence of the KT boundary extinction event? To address these two questions, I studied 81 palynological samples across the KT boundary of a stratigraphic section in Cesar-Rancheria basin, Colombia, northern South America. Several techniques, including range th rough method, rarefaction, per-capita extinction and origination rates, and measures of taxonomic diversity were used to estimate extinction percentages and the changes in diversity associ ated with the boundary in low latitude tropical environments. There is extinction percentage of 48-70% associated with the KT boundary and a

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10 significant change in the rate of extinction. Origination rates do not seem to be affected. The analysis show a high diversity Cretaceous pa lynoflora suddenly replaced by a low diversity association that dominated during the Paleocen e. The results suggest important changes in neotropical floras across the KP boundary, far more intense than in temperate regions.

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11 CHAPTER 1 INTRODUCTION The history of life on Earth has been punctuated by several episodes of global change known as mass extinctions. These episodes are characterized by profound climatic and environmental changes that molded the history of life and the pace of evolution. One of these catastrophic events occurred 65 million years ago and is known as the Cretaceous-Tertiary boundary (KT boundary) event. In the marine realm, several groups of organisms such ammonites (Marshall, 1995), calcareous nannofossils (Gartner, 1995), planktonic foraminifera (Keller, 1995), inoceramid and rudistid bivalves (MacLeod et al., 1990) either became extinct or were drastically reduced to a fraction of their former diversity. On land, the most recognized group that became extinct were the non-avian dinosaurs and several other important groups of vertebrates showed a major decline in dive rsity and/or abundance (Archibald, 1995). The KT boundary episode was the focus of in tense debate for many years and several theories tried to explain the nature and cause of this mass extinction. In a gradualist scenario, long term global cooling and ma rine regression produced an acceleration of the background extinction (Officer & Drake, 1983, Hickey, 1981). In a catastrophic scenario, one or more extraterrestrial-driven environmental perturba tions were the main agents producing the mass extinction (Smith & Hertogen, 1980). In 1980, a team headed by Walter Alvarez (Alvarez et al, 1980) found strong evidence for what finally has been accepted as the cause of this cataclysm. In one section of the KT boundary located in Gubbio, Italy, Alvarez and his team found a thin clay layer enriched in the element Iridium which separates the Cretaceous from the Paleocene. Iridium is a rare element found only in very small amounts on the Earth, howev er it is very abundant in extraterrestrial bodies such as meteorites and asteroids. The iridium enrichment found at the KT transition links

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12 the impact of an extraterrestrial body to what happened 65 million years ago. Further discoveries of iridium anomalies in severa l marine and terrestrial KT boundary sections around the world have been discovered since Alvarez’s first discovery (Orth et al, 1981; Bohor et al., 1984; Nichols et al., 1986; Tschudy et al., 1984) supp orting the impact theory. The claystone that separates the Cretaceous from the Tertiary also contains an abundance of other mineralogical evidence for an extraterrestrial impact. Highly shocked terrestrial minerals (quartz, feldspar and zircon) that originated from rocks at the impact site (Morgan et al., 2006) have been found in terrestrial and marine sections of the KT boundary around the world. These shockmetamorphosed mineral grains show prominen t lamellar features (Bohor, 1987) occurring as multiple intersecting sets that are only known to be produced in three situations: rock associated with meteorite impact craters, nuclear bomb test sites, and high pressure laboratory explosive shock experiments (Short, 1968). Additional physical evidence of the impact includes microscopic spherules created by the condensation of melted silicate materials produced by the strike of the extraterrestrial object at cosmic velocities (Simons et al., 2004), anomalous amounts of rare elements (Izzet, 1990) and microscopic diamonds (Carlisle, 1992). This substantial, independent evidence supports the extraterrestrial impact theory as the cause of the KT boundary mass extinction. The crater produced by the impact was found one decade after the Alvarez team proposed the impact theory. Hildebrand et al. (1990), us ing magnetic and gravity field anomalies, discovered a 180-km diameter circul ar structure buried in the mi ddle of the Yucatan Peninsula, Mexico. The stratigraphy of this structure, called Chicxulub, revealed a sequence of andesitic igneous rocks interbedded with glass and breccias that contain evidence of shock metamorphism (Hildebrand et al., 1990). The chemical and isotopic composition of the sequence found in the

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13 crater is similar to those of deposits found in KT boundary sections. 40Ar/39Ar dating of core samples recovered from the impact breccia contained within the subsurface Chicxulub crater yielded a mean age of 64.98 0.05 million years (Swisher et al., 1992). The same age was also obtained for several KT boundary deposits around the world in conjunction with geochemical and petrological similarities suggesting that th e Chicxulub structure is the source for the spherules found at the KT boundary and is the KT boundary impact site. Subsequent analysis of samples taken from different KT boundary sites suggests that the body that impacted the Earth at the KT boundary was a CM2-type carbonaceous chondrite (Bottke et al., 2007). This type of asteroid is associated with what is now know as the Baptistina asteroid family, a cluster of fragments of a 170-km body that broke up between 190 and 140 million years ago in the main asteroid belt. According to Bottke et al. (2007), the collision between the Earth and a large fragment from the Baptistina asteroid shower 65 million years ago was the most likely cause of the KT mass extinction event. The impact produced many environmental pertur bations, including, among others, shifts in carbon cycle (Pierazzo et al, 1988), changes in precipitation and temperature (Wolfe, 1990), an increase in the CO2 dissolved in the sea, injection of sulfurous gases into the atmosphere (D’Hondt et al., 1998), temporary global darkness (Alvarez et al., 1980), global fires lasting for several months (Melosh et al., 1990), causing dras tic environmental and climatic changes that produced the collapse and reorganization of seve ral ecosystems and the extinction of marine (Kaiho & Lamolda, 1999) and terrestrial organisms (Orth et al., 1981; Tschudy et al., 1984). In sections deposited in terrestrial environments, the KT boundary has been detected by the coincidence of high concentrations of irid ium, the abrupt disappearance of certain pollen species (Nichols & Johnson, 2002; Bohor et al., 1984) and the presence of a low diversity fern

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14 assemblage at the beginning of the Paleocene. This so-called fern spike has been interpreted as the colonization of pioneer fern species in the aftermath of the KT crisis (Tschudy et al., 1984) The existence of this extinction level in ot her sections around the world (Braman et al., 1999; Vajda et al., 2001) indicates that several changes occurred within plant communities as a consequence of this environmen tal crisis. The palynological and megafloral record from mid latitudes show a dramatic and abrupt disappearance of most dominant taxa and nearly all of the late Cretaceous angiosperms following the KT bo undary. The basal Paleocene flora appears to be composed of taxa that were absent or ex tremely rare in the latest Cretaceous (Johnson & Hickey, 1990). An estimated loss of ~30-40% of palynomorph species has been seen throughout the western Interior of North America (Johnson et al., 1990). Palynofloral records from other places in the world (Hickey, 1981; Vajda & Raine, 2001) indicate that the effect of the KT boundary event was relatively minor in the southern hemisphere, suggesting a possible latitudinal extinc tion gradient, i.e decreasing extinction with increasing latitude (Wolfe & Upchurch, 1986). If this hypothesis were true, hi gh extinction levels would be expected in tropical areas. Howeve r, not a single section has been studied palynologically from the tropics (Figure 1-1) and the effect of the KT boundary on tropical vegetation is totally unknown. A clear understanding of the response of tropical vegetation to this environmental crisis is important to understand the effect of global cat astrophes on the vegetation and to compare the response of tropical vs. temperate vegetation to the same event. In the present study, palynomorph distribution across the Cretaceous-Tertiary boundary of one section located in the Cesar-Rancheria basin (northern Colombia) is studied. An analysis of

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15 diversity, extinction levels, ta xonomic rates and compositional changes through the boundary is presented. Previous palynological studies of the KT boundary in Colombia Using pollen and spores, Van der Hammen (1954a ), correlated the lower and middle part of the Guaduas Formation in the Eastern cord illera with the Umir Formation of the Lower Magdalena valley. Using amm onites and bivalves found by H ubach (1951), Van der Hammen (1954a) proposed a Maastrichtian age for the lo wer part of the Guaduas Formation and a Paleocene to lower Eocene age for the upper part of the Guaduas and Lisama Formation (lower Magdalena valley). During the Maastrichtian, the flora is largely dominated by angiosperms and primitive forms. Small changes in the numeric composition and some new species appear during the Maastrichtian and Van der Hammen (1954a) related these compositional changes to climate changes. A new type of flora found in the lower pa rt of the Lisama Formation and the upper portion of the Guaduas Formation is, accordi ng to Van der Hammen (1956b), the paleobotany evidence of the Cretaceous-Tertiary boundary. A co mplete change in the palynoflora with only few Cretaceous species seen in the Paleocene and an explosive radiation of new species is interpreted by Van der Hammen as the evidence of deep changes in the ecological conditions probably related to high Andean-alpine orogenic activity. Sole de Porta (1971) described several new genera and species from the Guaduas Formation and two assemblages be longing to the Cimarrona Forma tion, southern edge of the middle Magdalena valley (Sole de Porta, 1972). Acco rding to the foraminiferal association, the Cimarrona Formation is Maastrichtian in age. Th ere is no mention about the position, or the palynological changes across the KT boundary in these publications.

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16 Sarmiento (1992), studying one section of the Guaduas Formation lo cated in Sutatausa (northern Bogota), found 79 palynomorphs, 33 of which are new species. He proposed eight new genera and six new combinations. Based on the stratigraphic distribution of palynomorphs found in 61 samples, he divides the section in two z ones and subdivides the upper zone in to two sub zones. The Cretaceous-Tertiary boundary in the Sutatausa section is according to Sarmiento located between the zones one and two. Some of the criteria that he used to locate the KT boundary are: 1. A foraminifera association similar to those found by Martinez (1987) in the CesarRancheria basin (northen Colombia), indicating a late Masstrichtian age for the base of the Guaduas Formation. 2. Tropical cosmopolitan dynoflagellates (eg. Dinogymnium acuminatum), reported to persuit until the late Maastrichtia n, were found only in zone one. 3. Disappearance of palynomorphs close to the boundary between zones one and two. However, some of these species are found again in the middle of zone two. 4. The first occurrence of new species is, according to Sarmiento, one of the most important pieces of evidence to identify the KT boundary. Most of the first occurrences are found at the boundary between the two zones, however so me of them are found some meters below. 5. A paleocanal filled in its lowest part by fine carbonaceous material, well preserved organic matter, fossil leaves, teeth and phosphate nodul es. Overlying this sequence, a carbonaceous level with some fragments of vertebrates and teeth and the uppe r part of the channel filled by fine-grain sediments and some concretionary levels. According to Sarmiento, this could be the result of a catastrophic event associated with regional changes at the end of the Cretaceous. In summary, previous palynological studies of Cr etaceous and Paleocene sediments in Colombia suggested drastic changes in the vegetation at the end of the Cretaceous. Although the nature of these changes were not clear at the time that th e works were published, the palynological record was strong enough to show the importance of this transition. The nature and quantification of the changes at the KT boundary were probably beyond th e scope of these previous studies and are still elusive.

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17 In the present study, the palynomorph distribution across one section of the KT boundary in Colombia is presented to assess the changes in plant composition and diversity through the boundary and to calculate the palynological extinct ion percentages associated with the boundary. Biostratigraphy of the KT boundary in Colombia Continental sections of the KT boundary in th e Western Interior of North America have been associated with the extin ction of typical Cretaceous speci es of palynomorphs (Nichols & Johnson, 2002) and the existence of a “fern spike” that could represent colonization by pioneer species in the aftermath of the KT boundary cris is (Tschudy, 1984). The change in the vegetation has also been associated with physical eviden ce of the impact (shocked quartz, spherules and high concentrations of iridium and other rare elements) and evidence of environmental and climate change (alteration of the carbon cycle) th at links the changes observed in the vegetation with the event at the KT boundary. In this sense, palynology has been shown to be one of the most important tools to identify and locate the KT boundary precisely in continental sections from the western interior of North America. The disappearance of typical Cretaceous palynomorphs is a reliable indicator of the position of the KT boundary. Studies based on pollen and spores in Cretaceous and Paleocene sediments in Colombia and Venezuela (Pocknall et al., 1997; Sarmiento, 1992) have shown that an important proportion of palynomorphs recorded in Cretaceous sediments are absent in the Paleocene. This observation suggests that palynology could be used in tropica l sections to detect the KT boundary and the evidence associated with this event. However, only a few palynological zonations have been proposed for the Cretaceous-Tertiary transition in Colombia (Germeraad et al., 1968; Muller, 1987; Sarmiento, 1992). Germeraad et al. (1968) used several secti ons from tropical South America, Africa and Asia, to establish a broad palynological zonation on a pantropical scale that is further subdivided

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18 regionally (Figure 1-2). One pantropical zone ranging from the Maastrichtian to the middle Eocene ( Proxapertites operculatus zone), is proposed. This zone is characterized by the cooccurrence of Proxapertites operculatus Proxapertites cursus Spinizonocolpites echinatus and Echitriporites trianguliformis (Germeraad et al., 1968). The pantropical Proxapertites operculatus zone is subdivided in the Caribbean area in to three zones (Germeraad et al., 1968) (Figure 1-2): The Proteacidites dehaani zone, Retidiporites magdalenensis zone and Retibrevitricolpites triangulatus zone. The P. dehaani zone is characterized by the co-occurrence of P. dehaani and Buttinia andreevi and important percentages of F. margaritae (Germeraad et al., 1968). The boundary with the overlying Retidiporites magdalenensis zone marks the last appearance datum (LAD) of P. dehaani, Buttinia andreevi and the co-occurrence of R. magdalenensis Echitriporites trianguliformis and P. operculatus In the Caribbean area, the boundary between the Maastrichtian and the Dani an is located in the boundary between the Proteacidites dehaani and the Foveotriletes margariate zones (Figure 1-2). The F. margaritae zone is characterized by the co-occurrence of Stephanocolpites costatus Foveotriletes margaritae Longapertites vaneendenburgi Gemmastephanocolpites gemmatus and by the absence of Bombacacidites annae and Ctenolophonidites lisamae (Germeraad et al., 1968). Although the work of Germeerad et al. (1968) is based on numerous sources of information, their scope is regional and it is very difficult to es tablish useful biostratigraphic events (last appearances or first appearances) with enough stratigraphic resolution to identify the KT boundary. Muller et al. (1987) produced a refined versi on of the zonation proposed by Germeerad et al. (1968) by using information from different sed imentary basins in Venezuela. Three zones for the Maastrichian and three zones for the Paleocene are defined by Muller et al. (1987) (Figure 1-

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19 3). The boundary between the Maastrichtian an d the Paleocene is marked by the boundary between the Proteacidites dehaani and Spinizonocolpites baculatus zones. The base and top of the Proteacidites dehaani zone (zone 13) is defined by the first appearance datum (FAD) of Proteacidites dehaani and Spinizonocolpites baculatus respectively. The LAD of Foveotriletes margaritae Stephanocolpites costatus Proxapertites operculatus and Ulmoideipites characterize the base of the zone. The LAD of Buttinia andreevi Proteacidites dehaani Crassitricolporites brasiliensis Aquilapollenites and Scollardia characterizes the top of the zone. The base of the Spinizonocolpites baculatus zone (zone 14) is defined by the FAD Spinizonocolpites baculatus and the FAD of Gemmastephanocolpites gemmatus and the LAD of Spinizonocolpites baculatus define the top. The zone is also recording the FAD of Bombacacidites Mauritiidites franciscoi and is, in accordance with Muller et al. (1983), poor in ferns and gymnosperms. Most of the species that Muller et al. (1987) used for the zonation are not present in Colombia (e.g. C. brasiliensis, Crassitricolporites subprolatus, A. reticularis ) making their use difficult in other sedimentary basins. Also, the Campanian-Maastrichtian boundary was recently modified (Grandstein et al., 2005) and foraminifera zones that in the past were considered as Maastrichtian, now corresp ond to upper Campanian. This is probably the case of the Muller et al. (1987) zonation, indica ting that species that had been considered Maastrichtian could in fact be from the upper Campanian. Probably the most important work related to the KT boundary in Colombia using pollen and spores is that of Sarmiento (1992), who studi ed one section located in the western flank of the Checua-Lenguazaque syncline. Sarmiento (1992a) proposed two informal zones and subdivided the upper zone in to two subzones (Figure 1-4).

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20 The Buttinia andrevii zone (zone I) is characterized by the LAD of Echimonocolpites echiverrucatus, Spinizonocolpites echinatus, Re timonocolpites claris, Crusafontites grandiosus, Clavatriletes mutisi, Inaperturapllen ites cursis, Psilamonocolpites ciscudae and Retitricolporites belskii. Other important palynomor phs in zone 1 include Buttinia andrevii Ulmoidipites krempii and Zlivisporis blanensis which are abundant and frequent and although they disappear at the top of this zone, they are found again in zone II (Sarmiento, 1992a) (Figure 1-4). According to Sarmiento (1992), zone I corresponds to the “ Proteacidites dehaani zone” of Germeraad et al. (1968) and the “zone 13” of Muller et al. (1987) The relation between zone I of Sarmiento and the “ Proteacidites dehaanii ” zone of Germeraad et al. (1968) is based more on stratigraphic position than on palynological content (Sarmiento, 1992). The “Fovetriletes margaritae” zone (zone II) is characterized by the first appearance of 28 species, dominance of Angiosperms and Palms, and low presence of ferns (Sarmiento, 19 92). The zone is subdivided in two informal subzones: Subzone “II-A” (“ Zonotricolpites variabilis ” zone) and subzone “II-B” (“ Syncolporites lisamae ” zone) (Figure 1-3). The FAD of several species that have a wider dispersal and frequency in zone II-A is recorded below the boundary between zones “I” and zone “II”. For this reason the boundary between the tw o zones is regarded by Sarmiento (1992) as gradual. These species are: Proxapertites psilatus, Gemmamonocolpites dispersus, Crassitricolporites costatus, Syndemicolp ites typicus, Foveotriletes magaritae, Psilabrevitricolpites marginatus, Psilatr icolpites microverrucatus, Longapertites vaneendenburgi, Racemonocolpites racematus. Some of the species recognized by Sarmiento (1992a) with FAD at the boundary between zones “I” and “II” are: Longapertites perforatus Psilabrevitricolporites annulatus Mauritiidites franciscoi Zonotricolpites variabilis and Rugotricolpites oblatus Species having their FAD a few me ters above the boundary between

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21 zones “I” and “II” are: Echimonocolpites coni, Retibrevitricolp ites cf. inciertus, Retitricolporites exinamplius, Scabratricolpites thomasi, In certirrugulites carbonensis and Proxapertites operculatus. Finally, species having their FAD in the middle or the top of the subzone “II-A” are: Retitricolpites minutus, Retim onocolpites regio, Incertisc abrites pachoni, Zonotricolpites lineaus, Retimonocolpites retifosulatus, Striat ricolpites minor, Proxapertites verrucatus and Scabratriletes globulatus. Subzone II-B is characterized by the disappearance of 25% of the palynoflora (Sarmiento, 1992). Species with LAD in this zone include: Duplotriporites ariani, Bacumorphomonocolpites tausae, Ephedripites multicostatus, Araucariacites australis, Scabrastephanocolpites guadensis Zlivisporis blanensis and the FAD of Syncolporites lisamae, Spinizonocolpites tausae and Psilatriletes martinensis (Figure 1-4). Changes in the abundance of other species are also seen in this subzone. According to this study, the KT boundary is placed in the boundary between zones II and I and is characterized by the LAD of at least eight species of palynomorphs and zone II is characterized by the disapp earance of at least 25% of the pal ynoflora. Some inc onsistencies were observed in the data from the Sarmiento’s work an d interpretations must be considered carefully. For example, Sarmiento stated that Retimonocolpites claris is one of the palynomorphs that is found exclusively in zone I and disappears belo w the boundary between zones II and I. However in table 2a (Sarmiento, 1992), which contains the information about palynomorph distribution through the section, the LAD of Retimonocolpites claris is in sample 273, which according to the stratigraphic column, shows the position of the samples and corresponds to 690-700 m. This depth is in the middle to upper part of subzone II-A (Figure 1-3). Another inconsistency found in this work, is the FAD of Syncolporites lisamae According to the text in Sarmiento (1992), the FAD of this species is one of the features of z one IIB, however in table 2a (Sarmiento, 1992), the

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22 FAD of Syncolporites lisamae is in sample 276, which corresponds to the middle to upper part of zone II-A (Figure 1-4). Finally, Zlivisporis blanensis, according to the text is one of the palynomorphs that disappe ars in zone II-B, but according to the information in table 2a (Sarmiento, 1992), the LAD of this species is in sample 285 which correspond to 715-720 m in the stratigraphic column and is included in z one II-A. The inconsiste ncies found between the information reported in the text and the informatio n recorded in the tables, makes it necessary to view the stratigraphic range of the palynomorphs reported by Sarmiento with caution. For this reason, a comparison of the biostratigraphic ranges between the two sections was not performed. To asses the similarity between the two sections, the Sorensen index was calculated (Sorensen, 1948). The complete association found in each section was taken as one sample and the sections were then compared. The Sorensen index ranges from 1.0, when two samples have the same species, to 0, when there are no species in common (Jaramillo, 2008). For the comparison, Sorensen (SI)= 2a / (2a +b +c), where, a= total number of species present in both samples, b=number of species present only in Di ablito and c=number of species present in the Sutatausa section (Sarmiento, 1992). The index i ndicates low similarity between the sections (SI= 0.14). Table 1.1 summarizes palynomorphs that are shared by both sections. The results of the Sorensen index suggest that the two sections have a very different palynological composition. Part of this difference could be explained by the fa ct that some of the species that were described as “informal” in Diablito could be some of the species reported in Sarmiento. A more detailed taxonomic work is necessary in Diablito as well as a direct comparison of the species found in both studies. In spite of this, it is clear that a high proportion of the species found in Dibalito are not recorded in the Sutatausa section (e.g. Cricotriporites

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23 guianensis Terscisus crassa Stephanocolpites costatus Curvimonocolpites inornatus among others), probably indicating endemism.

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24 Figure 1-1. Map showing the locations of the KT boundary sections with continental records (modified from Nichols and Johnson, 2008) Figure 1-2. Palynological zonation proposed by Germ eerad et al. (1968). 1) Pantropical zone; 2) Atlantic zone; 3) Caribbean zone.

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25 Figure 1-3. Palynological zonation proposed by Muller et al. (1987). Figure 1-4. Palynological zonation of the Cret aceous-Tertiary boundary interval in the ChecuaLenguazaque section (Sarmiento, 1992).

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26 Table 1-1. Palynomorph species shared by th e Diablito and Sutatausa sections (Sarmiento, 1992). Species Annutriporites iversenii Araucariacites australis Bacumormomonocolpites tausae Buttinia andreevi Colombipollis tropicalis Crusafontites grandiosus Duplotriporites ariani Echimonocolpites protofrancisoi Echitriporites trianguliformis Foveotriletes margaritae Gemmamonocolpites dispersus Longapertites vaneendenburgi Mauritidites francscoi franc. Periretisyncolpites giganteus Proxapertites humbertoides Proxapertites operculatus Proxapertites psilatus Proxapertites verrucatus Psilamonocolpites medius Racemonocolpites racematus Retidiporites elongatus Retidiporites magdalenensis Spinizonocolpites baculatus Spinizonocolpites echinatus Syncolporites lisamae Syncolporites marginatus Syndemicolpites typicus Tetradites umirensis Ulmoideipites krempii Zlivisporis blanensis

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27 CHAPTER 2 OBJECTIVES The aim of this study was to analyze the palynol ogical content of one section encompassing the Cretaceous-Tertiary boundary. The section is a rock core drilled in the Cesar-Rancheria basin (northern Colombia). Eighty-one samples through the core were analyzed. The main objectives of this study were: 1. To analyze the pattern of diversity through the Cretaceous-Paleocene boundary. 2. To calculate the palynological extinction level and compare this level with those found in other KT boundary sections in North America.

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28 CHAPTER 3 GEOLOGY AND STRATIGRAPHIC FRAMEWORK Regional Geology The latest Maastrichtian to early Paleocene stratigraphic record in Colombia and western Venezuela is the product of the infilling of an el ongated, very shallow mari ne to coastal basin, with three depositional systems delivering sediments from the east, west and south (Villamil, 1990). During the Maastrichtian, the central axis of deposition was located along the present day western foothills of the eastern Cordillera of Colombia. With the uplift of the ancestral Central Cordillera, the axis gradually shifted eastwards to a position along the central axis of the present day Eastern Cordillera and extended to the north to a position near to the present-day Maracaibo lake where it remained until the Paleocene (V illamil, 1990). The asymmetric flanks of the ancestral eastern Cordillera produced two different facies associations that are recorded in the west and east flank of the Central cordillera. The western flank is composed of deep-water turbidites in the San Jacinto foldbelt (Molina, 1986) and the eastern flank is composed of deltaic and coastal environments widely distributed a nd reaching the Llanos foothills (Villamil, 1999). Facies derived from the west belong to the Li sama Formation in the Middle Magdalena Valley and Guadala and Seca Formations in the Up per Magadalena Valle y (Villamil, 1990). Similar units of this age, but derived from the east, are the Molino and Barco Formations that are the scope of this study. Litostratigraphy and Depositional Environment Samples from Diablito are distributed along 1313.4 feet of core. The section comprises the Molino Formation, the Barco Formation, and the Cuervos Formation. A general stratigraphic column with the location of the samples is shown in Figure 3-1.

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29 Molino Formation The Molino (Catatumbo) Formation was named by Notestein et al (1944) from the Catatumbo Creek, in the department of Norte de Santander (Colombia). However, the outcrops in the river are not well preserved and the type section was transferred to a section obtained from the well “Oro numero 3” in the field Rio de Oro (Venezuela). The Molino Formation is composed of shales, often carbonaceous, with some ferruginous nodules and sporadically intercalation of fine sandstones. Thickness ranges from 300 to 600 feet. According Van der Hammen (1954, 1958) and Hubach (1957), the lower part of the formation is Maastrichtian in age. The Molino Formation in Diablito is at least 755 feet thickness, from the base of the recovered core (2300’) to 1545’ (Figure 3-1) and is mainly composed of biomicrites, finegrained glauconitic sandstones and sublitharenites. Barco Formation The Barco Formation was named by Notestein et al. (1944) from the anticline de Petrolea located in Sierra Barco del Este. The formation is composed mainly of sandstones, lutites and claystones. In the upper part of the section it is common to find one or two coal beds. The finegrain sediments (lutites and claystones) form a third part of the total thickness of the formation. Thickness ranges from 500 to 900 feet. The contact with the underlying Molino Formation is apparently concordant. The upper c ontact is normal and is marked by the appearance of the first important sandstone of the Cuervos Formati on. Van der Hammen (1958) dated the Barco Formation as early Paleocene based on pollen. In Diablito, the contact between the Molino Formation and the overlying Barco Formation is irregular. The formation is 1000 feet thickness and is composed of sideritic mudstones, fine-grained litharenites with calcareous cement, and sporadic coal beds in the lower part of the formation (Figure 3-1)

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30 A detailed sedimentological description and depositional environmen t interpretation of the KT boundary interval was done by German Bayona (written communication, 2006). The interval extends from 1755’ to 1540’ (Figure 3-2). Below 1645’ the sequence is characterized by a coarsening-upward sequence in which the dominant lithology is dark mudstones with s cattered fine sandstone beds. The thickness of the sandstone beds does not exceed 5 feet. Few small coal beds, < 1 feet thick, are present. Bioturbation is common as well as plant remains. The depositional environment for this sequence is interpreted by Bayona (pers. communi cation) as a prodelta to delta front (Figure 3.2). Above 1645’, the sequence is characterized by a fining-upward sequence and is mainly dominated by light-color siltstones with plane parallel lamination, scattered thin sandstone beds and small coal beds. This lithology suggests fine-g rained bay fill and channel fill successions in a delta front and delta plain. (Figure 3-2).

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31 Figure 3-1. General stratigraphic column of Diablito. Numbers on the palynological sample correspond to sample identification number and reflect the stratigraphic position of the sample

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32 Figure 3-2. Stratigraphic column of the interval where the KT boundary is located. Sedimentological description and depositi onal environmental interpretation done by German Bayona (written communication, 2006).

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33 CHAPTER 4 MATERIALS One rock core drilled by the DRUMMOND Coal Company in the Jagua de Ibirico (Cesar-Racheria basin, northern Colombia) (9 34’ N ,73 16’ W) was studied (Figure 4-1). The core (DIABLITO) is 2300 feet thickness and comprises, from older to younger, the Molino Formation (755 feet), the Barco Formation (966 feet), and the Cuervos Formation (579 feet). Samples were prepared at the Instituto Colombiano del Petroleo by the standard procedure of digesting the sediments in HCl and HF (Traverse, 1988) and then oxidizing. Thirty grams of sample were crushed and placed in a one-liter beaker. A 25% solution of HCl was added and left overnight to di ssolve carbonates. The HCl was decanted and the supernatant was discarded. The remaining muddy liquid was then centrifuged for 2 minutes at 1500 rpm and the supernatant was discarded. This step was repeated until the supernatant was completely clear. After the carbonate removal, the sample was transf erred to a copper beaker and placed in a fume hood. Then, 70% HF was added to the sample for ~ 24 hours. The sample was transferred to a polystyrene centrifuge tube and washed twice with water. The residue was transferred to a 50 ml glass centrifuge tube and 25% HCL was added. The residue was then centrifuged and decanted. The washing process was repeated until all by-pro ducts from the HF reaction were removed. To remove the fine organic material, 5 ml of Darvan # 4 solution was added to the residue and filled with water. A short centrifugation was done at 15 00-rpm for about 60 seconds. This process was repeated until the supernatant was clear. The residue was acidified with HCL for a better heavy liquid separation and the residual minerals were removed by decanting off the lighter organic fraction using a zinc bromide (ZnBr2) solution adjusted to a specific gravity of 2.0. Samples were allowed to sit for ten minutes before centrifuging for 15 minutes at 2000 rpm. Schultz solution was poured in to the tube with the residue and th e tube was placed in hot water for 4-12 minutes.

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34 The samples were washed several times (3-4) until the solution was neutral. A 10% NH4OH solution was added to the sample, which was placed in a hot water bath for 2 minutes. The sample was washed and centrifuged three times and sieved using a 7 m nitex screen cloth. Using a pipette, several cc of residue were siphoned and mixed with one drop of polyvinyl alcohol. The mix of residue and polyvinyl alcohol was distributed over the cover glass evenly and homogenously. When the polyvinyl was dry, a dr op of clear casting resin was placed on the slide near the center. The cover slip was turned and sealed. The slides were then dried for 24 hours. Two light microscopes were used for routin e palynologic analyses. A Carl Zeiss light microscope (Scope 2, # 4311267, Pa leobotany Laboratory, Florida Museum of Natural History) and a Nikon Eclipse 200 (Center for Tropical Paleoecology and Archaeology, Smithsonian Tropical Research Institute). For each palynolog ical slide, the oxidi zed and the non-oxidized residue was completely scanned with a 20x Ze iis planapochrormatic objective. At least 300 pollen/spores per sample were counted when poss ible. In a pollen count of 300 grains, taxa with >1% frequency are usually detected (Weng et al., 2006). When this number was reached, the remainder of the slide was scanned, without counting, to find new species. Examination and description of the palynological material was done using a 100x Zeiss oil inmersion planapochromatic objective. Identification of the palynomorphs found in this study, was done by comparison with photographs and descriptions of Cretaceous an d Paleocene material published for Northern South America (Van der Hammen, 1954a 1954b; 1956a; 1956b, 1966; Gonzales, 1967; Germeraad et al., 1968; Sole de Porta, 1971, 1972; Van der Kaars, 1983; Muller, 1987, Sarmiento, 1992; Sarmiento et al., 2000, Jaramil lo et al., 2001; Yepes, 2001, Jaramillo et al,

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35 2007) and comparison with the fossil pollen reference collection of the Smithsonian Tropical Research Institute and the Instituto Colombiano del Petroleo.

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36 Figure 4-1. Topographic map showing the location of Diablito (9 34’16 W, 73 16’ 45 N).

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37 CHAPTER 5 METHODS Diversity pattern through the KT boundary Ecological diversity can be measured in three different ways (Magurran, 1988): 1) counting the number of species, 2) by describing the relative abundances of species, 3) using one of several indices that combine information of these two components. In this study, several techniques were used to analyze the patterns of diversity. Richness and Rarefaction The number of species found in a study area is referred to as Richness (S) (Hayek and Buzas, 1997). This measure does not take into acc ount the number of individuals per species, or the way individuals are distributed among speci es. Richness is a function of the number of individuals counted and the probability of finding greater richness increases as the number of individuals counted increases (Magurran, 1988). Although 300 grains per sample were counted when possible, many of the samples did not reach this level, and the differences in richness between two samples can be due to differences in the number of counted grains and not to biological or ecological factors. Sander’s rarefaction, a sample reduction method (Hayek and Buzas, 1997), was used to estimate how many specie s might have been found within a sample if the sample had been smaller. In this way, th e richness between two samples with different size was be compared. Rarefaction values of 50, 75, 100, 150 and 200 specimens were used to test if the differences in richness were a consequence of different counts level. The unbiased version of the original Sandler’s formula was used (Hubert, 1971): = n N N N S Ei1 ) ( (5-1)

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38 Where, E(s) = Expected number of species. n = Standardized sample size. N = Total number of individuals. Ni = Number of individuals in each species Shannon-Wiever Index (H) Ecological diversity indices are the combina tion of the number of species (richness) and the distribution of individuals among these speci es (evenness). Several indices have been developed and basically they differ with respect to contribution of each of component to the index. The Shannon index (H) is the most common of the diversity indices. It is based on information theory and was derived indepe ndently by Shannon (Shannon, 1948) and Wiener. The index assumes that all the individuals come from a random sample of an infinite population and every species is represented in the sample (Magurran, 1988). H is calculated using: i ip p H ln = (5-2) where “ pi” is the proportion of individuals found in th e “i” species. However the real value of “pi” is unknown, it can be estimated as (ni / N), where “ni” is the number of individuals in the “i” species and “N” is the total number of individua ls (Magurran, 1983). H is equal to zero when there is only one species in the sample and a larger values of H occur when individuals within species are equally abundant. The value of H nor mally ranges between 1.5 and 3.5 (Magurran, 1988). The Shannon index was calculated for each sa mple to asses is there were differences between the Cretaceous and Paleocene samples. Range Through Method The Range-Through method (RTM) was used to estimate the standing diversity and the per capita extinction and origination rates. In the RTM, every species is considered present in all

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39 the samples between its first and last appe arance datum (Boltoskoy, 1988). This method smoothes the often spotty recovery of mic rofossil taxa and minimizes the effects of environmental influences (Hazel, 1970). The sing leton taxa (species represented by a single specimen) were eliminated from the analysis b ecause empirical and cla dogenetic models have shown that diversity measurements are best estimated if singletons are excluded (Sepkoski, 1990). Standing Diversity The Standing Diversity (SD) is an estimate of the taxonomic diversity of the group at the midpoint of a time interval (Harper, 1975), and it does not depend on the interval length (Foote, 2000). Each species occurrence known or inferred from the RTM was classified into one of the four fundamental classes of taxa de scribed by Foote (2000) (Figure 5-1). 1) FL : taxa confined to the interval with firs t appearance datum (FAD) and last appearance datum (LAD) both within the interval. 2) bL : taxa that cross the bottom boundary a nd have their LAD during the interval. 3) Ft : taxa that have their FAD during the interval and cross the top boundary. 4) bt : taxa that range through all the interval and cross both the bottom and top boundary. The SD was calculated for each sample using the proportional difference between the number of taxa crossing into an interval (botto m boundary crossers (Nb)) and the number of taxa crossing out of an interval (top boundary crossers (Nt)) (Foote, 2000) (See table 5.1 for equations). Edge Effect and Piecewise analysis The standing diversity calculated for each sa mple is based on the range through method; however when the interval falls toward either edge of the section the ability to infer the presence of the taxon by the range through method diminishes, creating an edge effect at both extremes of

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40 the section (Foote, 2002). The edge effect artific ially increases the number of first appearances and last appearances at the oldest and youngest pa rt of the section, respectively, creating an apparently abrupt decline in the standing diversity (Foote, 2006). To estimate the edge effect, a piecewise re gression analysis was done. The procedure assumes that two different regression functions fi t the same data and try a two-segment fit. The intersection of the two fitted regression lines is the breakpoint. The breakpoint is changed to all the possible positions and by iteration the position of the breakpoint that produces the regression with the lowest residual sum of squares is chosen (Yeager et al., 1989). The model follows the algorithm described in Duggleby and Ward (1991), modified by Jaramillo et al. (2006) for a twosegment linear regression: y= yt + [(mL + mR)(x-xT) [(mL + mR) x-xt ]/2 (5.3) Where, y = FAD or LAD x = species xt = breakpoint species yt = breakpoint FAD or LAD mL = slope left of breakpoint mR = slope right of the breakpoint A piecewise analysis was performed at the base and top of the standing diversity curve to eliminate the border effect. Graphic Correlation and Taxonomic rates Taxonomic rates refer to the rate at which new species originate and existing species become extinct (Foote, 2006). The per-capita origination ( p ) and extinction ( q ) rate is a measurement of the number of originations and ex tinctions scaled to the number of species at risk and to the time that they are at risk (Foote, 2006). Because p and q decline as interval length

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41 increases (Foote, 1994) it is necessary to subdivide the section in equal time intervals. The age of two levels in Diablito were roughly estimated usi ng the age of two key biostratigraphic events compiled from Jaramillo & Rueda (2004). These events were projected into Diablito using graphic correlation. This is a deterministic biostratigraphic technique (Copper, 2001) where a two-axis graph is used to express time equiva lence between two stratigraphic sections (Shaw, 1964). The events (FAD and LAD) that occur in bot h sections are plotted as points and if they are synchronous and the sedimentation rate is equa l, the points would plot on a straight line with slope equal to one (Hammer and Harper, 2006) However, because the fossil record is incomplete and the sedimentation rate is usually unequal, the observed order of events in two sections is normally different, producing a cloud of points in the scatter plot. The objective of graphic correlation is to fit the points to a straight line or segments of line and the best solution is the line of correlation (LOC) that causes the minimum disruption of the best-established ranges (Edwards, 1995). Establishing the LOC is the most problematic part of the graphic correlation (Edwards, 1995). Although sophisticated techni ques can be used to trace the LOC (e.g. Constrained optimization (Sadler, 2003); Gene tic Algorithms (Zhang, 2000)), with a good biostratigraphic and geological knowledge of th e sections the LOC can be traced manually (Hammer and Harper, 2006). Once the LOC is traced, the range of taxa in one section can be projected onto the most complete section to pr oduce a composite section. This procedure is repeated with all the available sections until a stable composite section is obtained (Zhang, 2000). Diablito was plotted against one section that spans the KT boundary in Rio Loro, Venezuela. The biostratigraphic information for this section was taken from Jaramillo et al (2006) and Yepes (2001). The line of correlation was traced manually and the ages of two key

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42 biostratigraphic events were projected on Diablito These data were used to calculate a rough sedimentation rate through the section and with this information it was possible to divide the section into one million time intervals. Taxonomic rates (p and q) were then calcula ted using the number of taxa that range completely through each interval (both boundary cro ssers (bt)) relative to the total number that cross into or out of the interval (bottom or top boundary crossers (bL, Ft)) (Foote, 2000) (See Table 5-1 for equations). Cluster Analysis Cluster analysis is an exploration and visuali zation technique that allows one to separate groups of samples with similar composition from other samples. Such groups are searched on the basis of similarities in measured or counted data between sample s. This analysis is sometimes preceded by transformation (eg. logarithmic tran sform, conversion of numerical abundances to presence/absence values) and standardization (s tandardization to total, standardization to maximum and z transform) that make the data more amenable for statistical analysis and weight samples so that they contribute to the statistical analysis more equally (Olszewski, pers. communication). To assess the similarity between sa mples, a distance-similarity measure is used and a clustering algorithm that defines the distance between the clusters (Hammer and Harper, 2006) is chosen. Classical clustering in paleo ecology and biology has used the agglomerativehierarchical approach. In this algorithm, every clustering step is governed by the recalculation of similarity coefficients between established clusters and the possible candidates, and an admission criterion for a new member (Sneath & Sokal, 1973). Possible changes in the palynological compos ition between the Cretaceous and Paleocene samples were tested using an agglomerative-hierarchical cluster analysis. A presence-absence transformation was used to run the analysis a nd range through was assumed. Euclidean distance

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43 (root sum of squares of the differences) and Manha ttan distance (sum of the absolute differences) were used as metrics to calculate the dissimilarity between the samples and several clustering methods (average, single, complete ward and weighted) were tested and their results compared to achieve the best results. Extinction percentages To calculate the palynological extinction per centage in Diablito, a Chi-square analysis was used. The procedure is similar to that used by Hotton (2003) in a KT boundary section located in Central Montana (U.S.A).This statistic compares the entire set of observed counts with the set of expected counts (Moore and McCabe, 2003). Chi square takes the difference between each observed and expected count and squares these values so that they are all zero or positive. To standardize, each squared difference is divided by the expected count. = ected ected observed X exp ) exp (2 2 (5-4) For each species in Diablito, the number of Cretaceous and Paleocene samples where a species was found is the observed count for each category (Cretaceous vs. Paleocene). The expected count is the number of samples where th e species would be expected to be found if the null hypothesis is true. The Chi square valu e for each species was calculated using : P P P K K Kected ected observed ected ected observed X exp ) exp ( exp ) exp (2 2 2 + = (5-5) Where k is Cretaceous and p is Paleocene. The first step in the analysis was character izing the distribution of palynomorph species above and below the KT boundary. Species were classified as belonging to one of three categories. Those species occurring either ex clusively below the KT boundary or undergoing

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44 highly significant (p<0.04) reduction above the KT boundary were termed K species. Species displaying no significant change in presence across the boundary were termed KT species. Those species undergoing significant increase in the Paleocene were termed P species. The extinction levels were estimated using the percentage of species in the K category with respect to the KT and K categories. All analysis was done using R for Statistical Computing (The R project for Statistical Computing, www.r-project.org)

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45 Figure 5-1. Four fundamental classes of taxa present in each stratigraphic interval. FL : species confined to the interval, bL : species that cross only the bottom boundary, Ft : species that cross the top boundary only, bt : species that cross both boundaries. (Modified from Foote, 2000). Table 5-1. Equations to calculate mean sta nding diversity and per capita extinction (q) and origination (p) rate for intervals of length t. Measurements are expressed in terms of numbers belonging to the four fundamental classes of taxa (see Figure 2) (modified from Foote, 2000) Measure Definition Mean Standing Diversity (Nb + Nt ) / 2 Per capita Origination rate, p -ln (Nbt / Nt ) / t Per capita Extinction rate, q -ln (Nbt / Nb ) / t Bottom-boundary crossers, Nb NbL + Nbt Top-boundary crossers, Nt NFt + Nbt

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46 CHAPTER 6 RESULTS The palynological content of 82 samples spa nning the Diablito rock core was studied. Three hundred and seventy morphospecies, including pollen, spores and dinocysts, were identified. The individual occurrence of 17.890 palynomorphs was recorded. Twenty-five species of dinocysts were found of which seven were not identified to the species level and simply regarded as sp. One hundred and twelve morphospecies of spores were found and nearly 70% are new, unnamed morphospecies. Of the 232 species of pollen, at least 55% are new morphospecies that have not been formally de scribed in the literature. Some of them were unnamed and some were regarded as sp. The unna med species are indicated by quotation marks. The species are not considered formally described because a dissertation is not considered a valid publication (Traverse, 1996) and formal description was beyond the scope of this study. Formal description of the morphospecies is found in the literature (Van der Hammen, 1954a, 1954b, 1956a, 1956b, 1966; Van der Hammen & Wymstra, 1964; Gonzales, 1967; Germeraad et al., 1968; Sole de Porta, 1971, 1972; Van der K aars, 1983; Muller, 1987; Sarmiento, 1991; Sarmiento et al, 2000; Jaramillo et al, 2001, 2007; Yepes, 2001) and photographs of some representative species encountered in this study are found in Appendix B. The list of morphospecies, their first appearance datum (F AD), last appearance datum (LAD) and number of samples in which they were found are listed in the Appendix A. Detecting the KT boundary To asses changes in diversity and palynologi cal extinction percentages in Diablito, it was necessary to first determine the position of the Cretaceous Tertiary boundary (KT boundary). The first line of evidence used to detect the KT boundary in Diablito was the disappearance of typical Cretaceous palynomorphs. The level where th ese species have their LAD is considered a

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47 good approximation of the position of KT boundary. According to previous studies (Germeerad et al., 1968; Muller et al., 1983; Sarmiento, 1992) sp ecies restricted to Cretaceous sediments in northern South America are: Buttinia andreevi Echimonocolpites protofranciscoi and Proteacidites dehaani Their stratigraphic distribution and abundance is shown in Figure 6-1. The LAD of Echimonocolpites protofranciscoi Buttinia andreevi and Proteacidites dehaani are 1635.7’, 1638.2’ and 1672.8’, respectively, placing the KT boundary between 1599.5’ and 1638.2’. In their last record, only one or two individuals were recorded. Cluster analysis shows that the palynological composition of samples 1635.7’, 1638.2’ and 1599.5’ is more related with the upper part of the section (Figure 6-16), suggesting that the last record of these three species could be indicating reworking. The sample with the last important record of Echimonocolpites protofranciscoi (recording the disappearance of more than 2 individuals) is at 1647.4’. This species is especially important because its stratigraphic range has been used in northern South America as a good indi cator of the late Cretaceous and its LAD has been used to identify the Mesozoic-Cenozoic boundary (Jaramillo, 2006). To identify the stratigraphic level in Diablito with the highest number of LADs, a histogram of the number of LADs throughout the section was constructed (Figure 6-2). By far the interval with the highest number of LADs (119 palynomorphs) is between 1600’ and 1800’. A plot of all the species with LADs in this in terval (Figure 6-3) shows a stepwise pattern of disappearances resembling a gradual extinction scenario. However, this is a sampling artifact related to the fact that most species composing a community are rare species and are only recorded in a few samples. The histogram of the number of samples in which each species was recorded between the base of Dialito and 1600 ’ (Figure 6-4) shows that 104 species were recorded in only 1 to 5 samples and only 15 samples were recorded in >5 samples. The

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48 probability of finding rare species in the samples immediately below the extinction layer is very low. This so called Signor-Lipps effect (Signor & Lipps, 1982) predicts that the distribution of last appearances of a group of species appears gr adual, even if all the species became extinct simultaneously. This pattern also makes it difficult to precisely pinpoint the stratigraphic position of the KT boundary that is usually represented by very thin stratigraphic horizons. The palynological record in Di ablito indicates a dramatic change in diversity around 1640’-1650’ (Figure 6.14). The change is coincide nt with the significant extinction of typical Cretaceous species (Figure 6.3) and the cluster an alysis (Figure 6.16) shows two very different palynofloras. All samples below 1640’ form one cluster and all the samples above 1640’ form the second cluster. Evidences suggests that im portant changes in the palynoflora occurred between 1640 and 1650’. To identify the position of the KT boundary more precisely and compare the biological evidence with an independent line of sedimentary evidence, a magnetic susceptibility analysis was performed between 1620’ and 1680’. Magnetic Susceptibility (MS) When an external magnetic field is applied to a rock sample, some of the mineral grains acquire an induced magnetization. MS is an indi cator of the strength of this induced magnetism within the sample and is largely function of the concentration and composition of the magnetizable material in the sa mple (Evans & Heller, 2003). MS in stratigraphic profiles has been related to the combination of two signals (Ellwood, 2001), a high-frequenc y and low amplitude signal associated with climate-driven cyclic changes in weathering and erosion, and an irregular and lowfrequency signal that is dominated by eustasy (Ellwood et al., 2003). When sea level rises, base level falls and erosion increa ses, thus more detrital grains are brought to the sediments, producing MS highs. The low frequency component of the MS signal can be used for global correlations because the mechanism that controls the signal is eustasy. Ellwood et al.

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49 (2003) used MS data from five KT boundary sections around the world (Figure 6.5) to establish a reference MS signature of the boundary that allowed narrowing the search for the impact evidence in new sections. The KT boundary sequence in all five sections starts from a clear decrease in the MS signature below the boundary, wh ich is interpreted to represent a global sea level rise in the latest Cretaceous (gray circle in Figure 6.5). Above the event layer produced by the impact, there is a major increase in the MS signature representing a rapid, but short period of enhanced continental erosion (Ellwood et al., 2003). This very distinctive and consistent pattern found in other KT boundary sections was used to narrow the interval where the KT boundary lies in Diablito. Magnetic susceptibility was measured in 200 samples spaced evenly through the 60-foot interval where, according to th e palynological evidence, the KT boundary is presumably located (Figure 6.6). Approximately 30 grams of sediment were used for each sample. MS was measured with a KLY-3 Kappabridge (Agico, Inc) by Victor Villasante (Laboratorio de Paleomagnetismo, Universidad Complutense de Madrid). Due to the probability of obtaining low MS values in certain lithologies (Evans & Heller, 2003), each sample was measured ten times and the average was calculated. Results are shown in Figure 6.6. The MS signature in Diablito is stable thr ough the whole section with a slight decreasing trend from the base to the top (Fig 6.7) and some sporadic increases in the MS restricted to some samples (1608.15’, 1622.95’, 1636.07’, 1641.32’, 1653.789’) (Figure 6.6). According to the paleoenvironmental interpretation, samples with high MS values are restricted to the mouth barprogradation and the delta front, however they come from different lithologies (Table. 6.1), indicating that high values in MS are not related to a particular lithology.

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50 The MS signature in Diablito decreases abruptly at 1647.5’ (Fig. 6.6). This pattern resembles those found by Ellwood in several sections of the boundary (Fig.6.5) and has been explained as the result of a global sea level rise in the latest Cretaceous prior to the KT boundary crisis. Above this level, Ellwood et al. (2003) found evidence, including an Iridium anomaly, a negative shift in 13C, microspherules and enrichment of rare elements that have been related with the KT event. The MS pattern seen in Di ablito indicates that the KT boundary probably lies at a depth between 1640’ and 1650’. In conclusion, several pieces of evidence suppor t placing the KT boundary in Diablito at a depth between 1640’ and 1650’: • Extinction of typical Cretaceous species (Figure 6.1). • High number of LADs recorded between 1600’ and 1800’ (Figure 6.2). • A dramatic change in diversity recorded at 1640-1660’ (Figure 6.14) • Cluster analysis, showing two different associations separated at 1640’-1650’. • The abrupt negative shift and subsequent p eak at 1645’-1647’ in magnetic susceptibility, resembling the pattern found in other KT boundary sections. (Figure 6.6). Additional analyses are being used to better identify the KT boundary event, including iridium concentrations, petrography and stable isotopes. The aim of these analyses is to detect the iridium anomaly that has been linked w ith the boundary, find micro spherules and shocked quartz related with the impact and to detect the negative C13 anomaly, that have been detected in other sections of the boundary. Diversity pattern through the KT boundary A diversity analysis of the pollen and spores record in Diablito was performed to know if the event at the KT boundary had a subs tantial effect on the vegetation

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51 Richness and Rarefaction The richness (S) (number of species), was calculated for each sample (Fig. 6.8) The mean richness of morphospecies for the Cretaceous samples is 28.8 and the mean number of morphospecies for the Paleocene samples is 17.5. To test if there is a difference in the mean ( ) number of species between the Cretaceous (c) and the Paleocene (t) a t-test was done. (Ha: c > t vs. Ho: c t). The t-test requires that the two popul ations from which samples were drawn have a normal distribution and equal variances. To assess the normality of the two data sets, a normal probability plot (QQ plot) for each populati on was constructed, a nd to test for equal variances (H0: 2 c = 2 t vs Ha: 2 c 2 t, where c: Cretaceous and t: Paleocene) an F test was done The QQ plot (Fig. 6.9) shows that the distribution of richness values for the Cretaceous and the Paleocene are roughly normally distribut ed. The F test, using an error type I ( : 0.01), indicated no significant difference between the vari ances with a p: 0.78 (F=1.09, df= 37). The result of the t-test, using an error type I ( : 0.01), suggests that the mean richness of the Cretaceous is significantly higher that the mean richness of the Paleocene with a p = 0.00002 (t: 5.26 and df: 76.8). Although 300 palynomorphs were counted when was possible, some samples did not reach this level and the differences in richness can be due to the fact that the richness increases with the sample size (Magurran, 1988) and not to ecological factors. For example, in the Cretaceous the mean of counts was 249 grains, howe ver, the sample with the lowest count was 53 grains, and there were two more samples with counts < 100 grains (82 and 65). In the Paleocene, the mean number of grains counted wa s 191, the sample with the lowest count had 15 grains and there are 14 more samples with counts < 100. To determine if differences in the counts explain the difference in richness, a raref action at 100 grains was done. Samples with <

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52 100 grains were excluded from the analysis (Fig. 6.10). The mean richness of the Cretaceous is still significantly higher than the richness of the Paleocene samples after the rarefaction, p < 0.001 (Cretaceous mean richness : 21 spp.; Paleocen e mean richness: 15 spp.) (t = 4.23, df = 63). The two conditions for the t-test, normal distri bution of the two population and equal variances were tested again for the reduced dataset and verified. Shannon Index Diversity indices characterize the diversity in terms of richness and evenness of a sample or community using a single number (Magurra n, 1988). The Shannon index (H) was calculated for each sample through the section (Fig 6.11). A ttest was performed to determine if the mean Cretaceous H ( =2.23) is higher that the mean Paleocene H ( =1.79). The F test, using an error type I ( : 0.01), indicated no significant difference betw een the variances with a p=0.37 (F=0.75, df= 43), however the QQ plot of the two populations (Fig. 6.12) show that normality cannot be assumed. In the case of the Paleocene, the extreme value of H (0.29) obtained for the sample 1438’ is an outlier that produces a distribution skewed lower values (Fig. 6.13) and in the case of the Cretaceous, three samples with low values of H also produce a distribution that is skewed to the lower values (1744’= 0.87; 1732.1= 1.0; 1706 = 1.29). For this reason the nonparametric Wilcoxon Rank sum test (also known as Mann-Whitn ey) was used to test the hypothesis of higher values of H in the Cretaceous. In this test the extreme values do not have a strong effect on the statistic, and it only require s equal variance, but does not require that the populations have a normal distribution (Ott & Longnecker, 2004). According to the test, the evidence suggests that the H of the Cretaceous is higher than the H for the Paleocene (W= 1292; p< 0.005).

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53 Standing Diversity The standing diversity, assuming range through me thod, was calculated for each sample (Fig. 6.14). The singletons (species occurring only in one sample) were rem oved and only pollen and spores were used in the analysis The abrupt increase and decline in standing dive rsity at the beginning and end of the section, respectively, is a product of the edge effect, wh ich artificially increases the number of FADs and LADs (Foote, 2006). To estimate this effect and obta in a more realistic pattern of the diversity, a piecewise analysis was applied to the standing diversity data. The edge effect at the oldest part of the section was estimated using the standing di versity values between the samples 2097.1’ and 1696.3’, and according to the analysis, the breakpoint is at 1885’. For the youngest part, the standing diversity between the samples 794.7’ and 1696.3’ was used, and the breakpoint was found at 988.8’. Finally, the samples between 1885.2’ and 2097’ and 794.7’ and 988.8’ were removed from the standing diversity curve (Fig 6.15). Changes in Composition Changes in the palynolofloral composition throughout the boundary were assessed using an agglomerative cluster analysis. The function Agnes from the package CLUSTER was used (R project for Statistical Computing). The numerical abundances were converted to presence-absence values and the range through method was assumed. Two distances were used (Manhattan and Euclidean) and three linking algorithms were tested (ward, single, average). The best result was obtained using Euclidean distance and the average linking algor ithm (unweighted pair-group average method, UPGMA)(Fig 6.16). The agglomerative coeffi cient (Kaufman & Rousseeuw, 1990), that measures the clustering structure of the dataset, was 0.74.

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54 Taxonomic Rates Graphic correlation was used to compare Diablito with one section that spans the KT boundary located in Rio Loro, Venezuela The bi ostratigraphic information of the Rio Loro section was taken from Jaramillo et al. (2006) and Yepes (2001). Thirty-six palynomorphs (pollen, spores and dinocysts) were used in th e graphic correlation and selected based in their common occurrence in both sections and their potential as biostratigraphic markers. The FAD and LAD of the taxa are summarized in Table 6.2 To roughly divide Diablito into equal time inte rvals, two biostratigraphic events compiled from Jaramillo et al. (2006), were projected from Rio Loro to Diablito. The two key stratigraphic datum’s are: 1. LAD of Echimonocolpites protofrancscoi has been used as the Mezosoic-Cenozoic boundary (65.50 0.3 My, (Grandstein et al., 2004)). The depth of this event in the Rio Loro section is 943 m. 2. The base of the Bombacacidites annae zone according to Jaramillo et al. (2006), corresponds to the carbon isotope shift of the early to late Paleocene (60.00 0.2 my). The FAD of Bombacacidites annae among others, characterizes the base of this zone (Jaramillo & Rueda, 2004). The depth of this event in the Rio Loro section is 1081 m. The line of correlation (Fig 6.17) was traced manually giving more importance to taxa with known high biostratigraphic value (e.g Echimonocolpites protofranciscoi Foveotricolpites perforatus Syndemicolpites typicus Proteacidites dehaani Buttinia andrevii ). The equation for the line of correlation is: X= -4.92Y + 5704 (6-1) Using equation 6-1, the projected LAD of Echimonocolpites protofranciscoi in Diablito is 1653.27’ and the projected LAD of Bombacacidites annae is 1060’ (Fig 6.17). A rough estimate of the sedimentation rate in the Diablito core was calculated using the slope of the line of correlation. The Y-axis was replaced for the time (My) of events.

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55 Slope (m) = X2 –X1 / Y2 – Y1 ; m = 1653.27 ‘ – 1060 ‘ / 65.5 My – 60.0 My m = 108’ / My The age for each sample was estimated using the equation of the line (6-2) that relates the depth of the two events ( Echimonocolpites protofranciscoi (1653.27’) and Bombacacidites annae (1060’)) and proposed age for these events (65.5 My and 60.0 My respectively). Y (My)= 0.009275 x Depth (feet) + 50.16 (6-2) With the assigned age for each sample, Diablito was then divided in 1 million time intervals and the number of species in each bin belonging to one of the four categories of Foote’s taxa (2002) was calculated (Table. 6.3). The per-capita origination ( p ) and extinction ( q ) rates (Foote, 2002) were calculate as: p = -ln (Nbt / Nt) / t (6-3) q = ln (Nbt / Nb) / (6-4) The results of p and q are shown in Figures 6.18 and 6.19, respectively. Extinction percentages The palynological analysis of Diablito show s that an important proportion of species recorded in the Cretaceous disappear at the proposed KT boundary (1640’-1650’) or some feet below the boundary (Fig. 6.20). Previous studies al so have shown that characteristic Cretaceous palynomorphs of northern South America have th eir last appearance close to end of the Cretaceous (Sarmiento, 1992). The extinction of palynomorphs in the Diablito was estimated as the number of palynomorphs (pollen and spores) seen in the Cretaceous that disappear below the proposed KT boundary in relation to the number of palynomorphs that are seen in the Cretaceous as well in the Paleocene. Using a chi square analysis, each species of pollen and spores found in Diablito was

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56 classified as belonging to one of three categories: 1) K species : species found only below the boundary or undergoing highly significant reduction in presence above the KT boundary 2) KT species : species displaying no significant change in presence across the boundary and 3) P species : species only found in the Paleocene or undergoing significant increase in presence in the Paleocene. A similar procedure was used by Hott on (2002) in one section of the KT boundary located in Central Montana, U.S.A. According to this analysis, and if all the species of pollen and spores are used, including singletons (species that were only recorded in one sample), the number of species in the K category is 172, the number of species in the KT category is 77 and the number of species in the P category is 96 (Fig. 6.21). Of the total number of species of the KT and P categories (249 spp) at least 69% (172) disappear below or at the proposed KT boundary. This percentage was taken as the extinction level. If the singletons are removed from the analysis, the number of species in the K category is reduced to 72 spp, the number of species in the KT category remains constant and the number of species in the P category is reduced to 44 spp (Fig. 6.22). The percentage of extinct species is 48%.

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57 Figure 6-1. Stratigraphic distribution and abunda nce of Echimonocolpites protofranciscoi, Buttinia andreevi and Proteacidites dehaani. E. protofranciscoi (LAD): 1635.7’;B. andreevi (LAD): 1638.2’; P. dehaani (LAD): 1599.5’. Figure 6-2. Histogram of the number of LADs. The highest concentrations occurs at a depth between 1600’ and 1800’

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58 Figure 6-3. Graphic showing LAD and FAD of species that disappear between 1600’ and 1800’. The pattern of extinction is gradual because of the Signor-Lipps effect (see text for explanation). Figure 6-4. Histogram of the number of samp les where the species with LAD between 1600’ and 1800’ were recorded.

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59 Figure 6-5 Magnetic susceptibility pattern found in five different sections of the KT boundary. All curves show a decrease in the MS signature before the boundary (gray circle) and a sharp increase across the KT boundary (arrow). Modified from Ellwood et al., 2003.

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60 Figure 6-6. Magnetic susceptibility (MS) pattern th rough the interval where the abrupt change in palynological diversity and extinction of typical Cretaceous species is detected (1600’-1700’). A negative shift in the MS signature is observed at 1647.5’ with a subsequent peak in MS at 1641.32’

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61 Figure 6-7 Magnetic susceptibility of the KT boundary interval in Diablito. A slight decrease in the MS is seen from 1600’ to 1700’ in the section (black line). Figure 6-8. Number of species (S) vs. Depth in Diablito. The KT boundary lies at approximately 1640 feet (horizontal black line).

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62 Figure 6-9. Normal QQ plot of the mean num ber of species (S) in the Cretaceous and the Paleocene. (TQ: theoretical quantiles, SQ: Samples quantiles) The condition of normality can be assumed

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63 Figure 6-10. Rarified richness at 100 grains. The mean richness for the Cretaceous is significantly higher than for the Paleocene (t-test: p <0.01). The KT boundary lies at ~1640 feet.

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64 Figure 6-11. Shannon index (H). The KT boundary lies at ~1640 feet (horizontal black line).

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65 Figure 6-12. Normal QQ plot of the mean Shannon index (H) of the Cretaceous and the Paleocene. (TQ: theoretical quantiles, SQ: Samples quantiles) The condition of normality can not be assumed.

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66 Figure 6-13 Boxplot of the Shannon index for the Cretaceous and the Paleocene. Cretaceous Paleocene

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67 Figure 6.14 Standing diversity using range-through method. Singletons were not used in the analysis. Note the abrupt increase and the decrease of the standing diversity produced by the edge effect. The KT bounda ry lies at 1640 feet (horizontal black line).

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68 Figure 6-15 Standing diversity using range-through method. Singletons were not used in the analysis. The edge effect was removed from the curve. The KT boundary lies at 1640 feet (horizontal black line).

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69 Figure 6-16. General stratigraphic column of Diablito showing lithology and Cluster analysis of the samples using Euclidean distance and the average method. The data were transformed to presence-absence and range through was assumed. The KT boundary lies at 1640’.

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70 Figure 6-17. Graphic correlation. Diablito vs. Rio Loro. See table 2 for the name and datum for each taxon. The line of correlation wa s traced manually (X=-4.92+5704). Two biostratigraphic events, Echimonocolpites protofranciscoi (LAD) and Bombacacidites annae (FAD), were projected from Rio loro to Diablito to divide the section in equal time intervals.

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71 Figure 6-18. Per capita origination rate calculate d using the per capita rates of Foote (2002). The origination rate per million years is stable through the section, however higher values are seen in the Cretaceous and the lower part of the Paleocene. The edge effect was removed from the data. The KT boundary lies at 1640’ (black line) Figure 6-19. Per capita extinction rate calculated using the per capita rates of Foote (2002). The extinction rate per million years shows low a nd stable values in the Cretaceous with an abrupt increase at the KT boundary. After the KT boundary (black line) the extinction rate shows low and stable values.

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72 Figure 6-20. Presence-absence distribution char t of pollen and spores recorded in Diablito. Note the high number of last occurrences at the proposed KT boundary (black horizontal line) and below the boundary Figure 6-21. Number of species in each of the K, KT and P categories. All the species of pollen and spores, including singletons, were used in the analysis. The extinction level was calculated using the percentage of the num ber of species in the K category with respect to the number of species in the KT and K categories (species recorded in the Cretaceous and the Paleocene). The extinction level is 69%. K category: species occurring either below the KT boundary or undergoing significant reduction in presence above the KT boundary; KT category : species displaying no significant change across the KT boundary and P category: species that were recorded only in the Paleocene.

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73 Figure 6-22. Number of species in each of the K, KT and P categories. The singletons were excluding for the analysis. The extinction leve l was calculated using the percentage of the number of species in the K category with respect to the number of species in the KT and K categories (species recorded in the Cretaceous and the Paleocene). The extinction level is 48%. K category: species occurring either below the KT boundary or undergoing significant reduction in presence above the KT boundary; KT category : species displaying no significant change across the KT boundary and P category: species that were recorded only in the Paleocene. Table 6-1. Lithology of samples with high magnetic susceptibility values. High values are not restricted to a particular lithology. Sample Lithology 1608.15 Mudstone-Siltstone light color 1622.952 Mudstone-Siltstone light color 1636.072 Sandstone 1653.789 Mudstone-Siltstone dark color 1641.32 Mudstone-Siltstone dark color

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74 Table 6-2. First (FAD) and Last (LAD) appearance datums for 71 taxa used in the graphic correlation. Biostratigraphic information of Rio Loro was taken from Jaramillo et al. (2006) and Yepes (2001). Diablito (feet) Rio Loro (m) code taxa FAD LAD FAD LAD 1 Andalusiella mauthei 1517.5 891 2 Annutriporites iversenii 1965.5 833.45 3 Ariadnaesporites sp. 1633.8 849 4 Bacumorphomonocolpites tausae 2018 976.6 5 Bombacacidites annae 794.7 1081 6 Buttinia andreevi 1638.2 900.1 7 Cerodinium diebelii 2018 910.5 8 Cerodinium pannuceum 1941.4 915 9 Cordosphaeridium sp. 1885.2 879.5 10 Corsinipollenites psilatus 1885.2 900.1 11 Crusafontites grandiosus 1849.4 900.1 12 Duplotriporites ariani 1885.2 910.5 13 Echimonocolpites protofranciscoi 1635.7 943 14 Foveotricolpites perforatus 931 1115.5 15 Gabonisporites vigourouxii 1648.1 936 16 Gemmamonocolpites dispersus 1672.8 953 17 Longapertites microfoveolatus 794.7 1157 18 Longapertites van eendenburgii 931 1185 19 Mauritiidites franciscoi var. franciscoi 1179.6 1022 20 Monocolpites grandispiniger 1797.9 910.5 21 Palaeocystodinium sp. 1885.2 943 22 Periretisyncolpites giganteus 1638.2 989 23 Proteacidites dehaani 1599.5 936 24 Proxapertites tertiaria 931 1188.5 25 Racemonocolpites racematus 1356.8 976.6 26 Retidiporites magdalenensis 794.7 1179 27 Senegalinium sp. 1672.8 922 28 Spinizonocolpites baculatus 1638.2 976.6 29 Spinizonocolpites echinatus 1751.7 871 30 Stephanocolpites costatus 1490.6 976.6 31 Syndemicolpites tipicus 1641.3 936 32 Tetradites umirensis 1641.3 922 33 Thalassiphora sp. 2097.1 910.5 34 Tricolpites aff. microreticulatus 1758.3 845 35 Trithyrodinium sp. 2062.9 915 36 Zlivisporis blanensis 1249.2 976.6

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75 Table 6-3. Number of species per bin in each one of the Foote’s taxa categories. The midpoint is the mid depth position between the lower and upper depth of the bin. X: number of taxa. bL: taxa that cross the bottom boundary and make their LAD during the interval; Ft: : taxa that ha ve their FAD during the interval and cross the top boundary; FL: taxa confined to the interval which FAD and LAD are both within the interval; bt: taxa that range through all the interval and cross both the bottom and top boundary; Nb : Bottom boundary crossers (NbL+Nbt); Nt : Top boundary crossers (NFt+Nbt) (See Fig.4). BIN Midpoint (Feet) XbL XFt XFL Xbt Nb Nt 1 812.65 38 0 5 0 38 0 2 904.1 26 3 14 35 61 38 3 1020.55 10 2 8 59 69 61 4 1109.85 1 0 2 69 70 69 5 1214.4 13 4 7 66 79 70 6 1332.7 10 6 5 73 83 79 7 1445.6 10 4 5 79 89 83 8 1553.1 17 10 13 79 96 89 9 1654.35 39 13 39 83 122 96 10 1757.75 12 18 31 104 116 122 11 1853.35 9 22 21 94 103 116 12 1979.7 2 38 21 65 67 103 13 2080 0 29 9 38 38 67 14 2244.4 0 38 10 0 0 38

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76 CHAPTER 7 DISCUSSION Several sections with continental records of the KT boundary have been studied in the northern hemisphere (U.S.A and Canada) showi ng dramatic changes in the vegetation as a consequence of the KT boundary event. The e ffect on tropical vegetation was totally unknown and not a single section had been reported from the tropics. In this work, I studied one section with a continental record of the KT boundary w ith the aim of detecting changes in diversity through the boundary and the extinction percentage associated with the KT boundary event. The section is a rock core (DIABLITO) drilled in the Cesar-Rancheria basin, northern South America, and is composed of 2200 feet of sandst ones, coal, and shales deposited in transitional environments during the Maastrichtian and Paleocene. In the western interior of North America, the KT boundary has been associated with the extinction of several palynomorphs and palynology ha s become one of the main tools to identify the boundary (Nichols and Johnson, 2008). The first line of evidence used in Diablito to detect the boundary, or at least to restrict the interval where the boundary is located, was the disappearance of species considered typically Cretaceous by some authors (Germeerad et al., 1969; Muller et al., 1983; Sarmiento, 1993; Jaramillo et al., 2006). The last appearance datum (LAD) of Echimonocolpites protofranciscoi Buttinia andrevii and Proteacidites dehanni show that the end of the Cretaceous in Diablito is located at a depth between 1638.2’ and 1672.8’. Additionally, the standing diversity curve (Fig. 6.14) shows an abrupt decrease in diversity between 1640’ and 1650’ and the cluster analysis depicts two very different palynological associations between 2244.4’ and 1641.3’ and between 1638.2’ and 794.7’ (Fig. 6.16). The histogram of the number of LADs (Fig. 6.2) al so shows a high concentration of disappearances in the interval where the other changes in the palynoflora are seen. The nature of these changes

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77 is discussed below, but is important to say that based on the palynological record, it was possible to narrow the KT boundary to an interval of approximately ~ 30 feet. Although a more detailed palynological study of this 30-foot interval w ould probably narrow even more the KT boundary interval, the nature of biological communities a nd the fossil record make the record of last appearances in a mass extinction scenario look gr adual, even if all the species became extinct simultaneously (Signor-Lipps effect). In extant and extinct communities, most of the species are represented by only a few individuals (rare species ) and most of the individuals that compose a community belong to only a few species (Magurran, 1983). The distribution of fossils is also controlled by lithofacies, sampling intensity and sample preservation (Nichols and Traverse, 1971). In this sense, the probability of finding individuals of rare species in samples below the extinction layer is very low a nd although an intense sampling near the layer could increase this probability, the product is only the smoothing of the Signor-Lipps effect. To identify the exact position of the KT boundary based only on the palynological record is difficult so to narrow the KT boundary inte rval in Diablito, magnetic susceptibility (MS) analyses were carried between 1600’ and 1700’. E llwood et al. (2003) used several sections to establish a reference magnetic susceptibility signature for the KT boundary. According to this study, below the boundary there is a sudden decrease in MS that represents a sea level rise in the latest Cretaceous, followed by a major increase in MS interpreted to represent a rapid, but short period of enhanced continental erosion (Ellwood et al., 2003) (Fig. 6.5). Between these two levels, Ellwood reported an iridiu m anomaly, a negative shift in 13 C and microspherules that allow precise location of the KT boundary and as sessment of the relation between the boundary and the MS signature.

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78 The negative shift in Diablito at 1647.5’ (Fig. 6.6) is very similar to those found by Ellwood et al. (2003) immediately below the KT boundary in different sections around the world. Above the negative shift, several MS peaks are found in Diablito. The peaks are independent of the lithology and facies and a lthough similar facies and lithology are find in the lower part of the section (below 1647.5’), only one peak is found below 1653.7’, suggesting that the high MS values are restricted to the upper part of the section. A detailed study of the mineralogical composition of the samples is necessary to test if the peaks in MS found in the upper part of the section can be explained by diffe rences in the concentration and/or composition (mineralogy and grain size or shape) of the ma gnetizable material in the samples above and below the negative shift. These factors are largely responsible for the MS signature in a rock sample (Ellwood et al., 2003). The first significant p eak above the MS negative shift is located at 1641.32’ in Diabltio. According with the interpretation of Ellwood et al (2003) this peak is located above the iridium anomaly, and other evidence of the KT boundary (shocked quartz, spherules, etc…), indicate that if the Ir anomaly is preserved in Diablito, it is probably located between 1641.32’ and 1647.5’. Finally, the sections studied by Ellwood et al. (2003) were deposited in deep oceanic environments. It has been suggested that the MS signature will not be useful in non marine sections, very proximal marine s ections, or sections that are severely diagenetically modified (Ellwood et al., 2003). The interval where MS was measured in Diablito (1600’-1700’) represents deltaic environments (Fig. 3.2), sugges ting that MS analysis probably can be used in sections representing more transitional environmen ts of deposition. It will be important to study the MS signature of sections with environmen ts of deposition similar to Diablito to corroborate

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79 the results found in this study. If the same pattern is found in other section, MS analysis can be used not only to narrow the search for the KT boundary, but also as a correlation tool. Cluster analysis shows two major and very distinctive palynological associations in Diablito (Fig. 6.16). One cluster is composed of the samples between 794.7’ and 1633.8’, and samples between 1635.7’ and 2244.4’ compose a nother cluster. In terms of palynological composition, the sample at 1633.8’ is more similar to the sample at 794.4’ than to the sample at 1635.7’ even the distance between them (~ 840 foot) is almost 400 times the distance between 1633.8’ and 1635.7’ (~ 2’). Also, the palynological composition of the sample at 1635.7’ is more similar to the sample at 2244.4’ even though the distance between them is ~ 610’. These results suggest deep changes in the composition of th e palynoflora between 1630’ and 1640’. According to the magnetic susceptibility analysis, this interv al is very close to where the Iridium anomaly and other evidence of the KT boundary would be located, demonstrating that the changes observed in the palynological composition are related with the KT boundary event. The number of species, referred to as Richness (S), is related to the sample size. Increasing the sample size increases the number of species (Rosenzweig, 1995). The recovery of palynomorphs is variable in the samples studied in Diablito and this difference could account for the differences found in S between the samples. In the 40 samples studied below 1635.7’ (Cretaceous samples) the mean number of pa lynomorphs counted was 249 individuals, with a minimum and maximum of 59 and 328 individuals, re spectively, and a standard deviation of 83.7. In the 42 samples studied above 1635.7’ (Paleocene samples), the mean number of palynomorphs counted was 191 individuals wi th a minimum and maximum of 15 and 324 individuals, respectively, and a st andard deviation of 120. The differences in the mean number of counted grains below and above the boundary is significant (t-test, p=0.013) indicating that

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80 number of palynomorphs counted in the Cretaceous is higher than the number counted in the Paleocene. The difference in S between the Cretaceous and the Paleocene could be the result of this difference. In the Paleocene, 14 samples of a total of 42 have < 100 grains. One possible explanation for the poor recovery in the Paleocen e is the effect that the KT boundary event had on the vegetation. Because of the environmental crisis, a high proportion of species and individuals were eliminated If this reasoning is true, an upward increase in the number of grains should be seen in the Paleocene. Samples immedi ately above the boundary are expected to have low recovery than samples upward in the section, which are expected to have more taxa as a result of the recuperation of the vegetation. However the number of grains counted in the Paleocene does not show any trend. Another explanation is that during the Paleocen e the vegetation was mostly dominated by a few species. In this scenario, the probability of findi ng individuals of the dominant species is higher than the probability of finding rare species. If this is true, a high value of dominance should be found in the Paleocene. Pielou’s evenness index (J) evaluates the variation in the species abundances among a community. When all the species have the same number of individuals, J is equal to 1 and when most of the individuals be long to very few species J tends to low values (Jaramillo, 2008). The mean J for the Paleocene samples is 0.66 with a minimum and maximum value of 0.12 and 0.92, respectively, and standard deviation of 0.16. This mean value of J is not significantly different from the mean J value of the Cretaceous samples (mean=0.64, min=0.36, max=0.85, sd=0.12) (t-test, p=0.63). According to these results, the low recovery of some of the Paleocene samples could not be satisfactorily explained by the evenness of th e Paleocene samples nor the effect of the KT boundary event on the vegetation. The distributi on and recovery of palynomorphs is also

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81 controlled by lithofacies, sample position in systems tracts and sample preservation (Holland, 1995) and these factors could explain the poor r ecovery in some of the Paleocene samples. Further analyses are necessary in order to test this idea. One way to account for the difference in the number of grains counted is rarefaction. A level of rarefaction of 100 grains was used a nd samples with < 100 grains counted were excluded from the analysis. Rarefaction analysis (Fig. 6.10) indicates that the Cretaceous samples tend to have a higher richness than Paleocene samples, regardless of the number of grains counted in each sample. Diversity indexes are a combination of th e richness as well as the distribution of individuals among the species and they allow comparisons among samples regardless of the original sample size (Rosenzweig, 1995). The Shannon index calculated for each sample indicates that there is a trend toward decreasing diversity from the Cretaceous to the Paleocene (Fig. 6.11) from a mean of 2.2 (standard deviation=0.48) in the Cretaceous to a mean of 1.79 (standard deviation=0.43) in th e Paleocene. One isolated Pale ocene sample (1438’) yielded a Shannon index of 0.29, fewer than all of othe r Cretaceous or Paleocene samples. However this sample could have a strong biofacies control (dominated by Proxapertites operculatus ) that may be producing this low value. Standing diversity was calculated in Diablito using the range through method that tends to eliminate facies and sample size effects. Singletons were not used in the analysis because they introduce noise and mask the diversity signal (F oote, 2000). The edge effect was removed from the analysis using a piecewise regression. The standing diversity shows a high diverse Cretaceous palynoflora abruptly replaced by a lo w diversity Paleocene assemblage, from a mean of 120 species (standard deviation=2.5) in th e Cretaceous to a mean of 83 species (standard

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82 deviation=10.6) in the Paleocene. The change in standing diversity is not sudden, but gradual and occurrs through a 20-foot interval. Taxonomic rates in the sense of Foote (2000) are sensitive to interval length. Diablito was subdivided into one million-time interval using graphic correlation and key stratigraphic datums compiled by Jaramillo et al. (2006). The pe rcapita origination rate shows high values in the two bin of the Cretaceous (Fig 6.18). Piece-wise regression analysis was used to remove the edge effect, however the marine influence at th e base of Diablito, as shown by the presence of dinocysts and foraminifera, spread upward the section the first appearance of most of the species of pollen and spores, and produce an extended edge effect. The effect is probably affecting all the Cretaceous, however in Figure 6.18 the last two bines of the Cretaceous were not removed for the graphic. The two first bin after the KT boundary show a decreasing trend in the origination rate, and from 1450’ to the top of the section the rate is stable. The Paleocene in Diablito is characterized by stable origina tion rates and nonsignificant changes above background levels. Only a few new species are reco rded in the Paleocene, suggesting that the time that the palynoflora needed to reach dive rsity values as high as those observed in the Cretaceous is beyond the record of Diablito. This result is supported by the standing diversity analysis that shows low diversity values during the Paleocene. The per capita extinction rate shows low va lues before the KT boundary. Suddenly the rate increases almost four times the values observed in the previous bin. The change is coincident with the interval where the KT boundary is locat ed and with the change in standing diversity, indicating that the increase in the extinction ra te is responsible for the change in standing diversity.During the Paleocene the extinction ra te is stable and non-significant changes are observed.

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83 The estimation of palynomorph extinction pe rcentages at the KT boundary depend on whether the measure is based on the megaflor a or palynological record (Nichols and Johnson, 2008). Even though leaves and paynomorphs are deri ved from the same vegetation source, their taxonomic resolution is different. Palynology ha s coarse taxonomic resolution; fossil pollen genera and species can be thought of as re presenting fossil botanical families and genera, respectively (Nichols and Johnson, 2008). On the other hand, megaflora provide high-resolution taxonomic data (Nichols and Johns on, 2008). Initial interpretations of the megaflora and pollen records of North America reflect extinction leve ls between 60-70% and 15-30%, respectively, at the species level (Wolfe & Upchurch, 1986). La ter analyses using quantitative methods and based on the disappearance of species in the uppermost 5m below the KT boundary, revealed extinction levels as high as 57% for the megafl ora and between 17 and 30% for the palynoflora (Wilf and Johnson, 2004). The range calculated fo r the palynoflora by Wilf and Johnson is almost identical to Hotton’s (2002) estimate for eastern Montana (USA). Hootn used a chi square analysis and found a percentage of extinction between 17-30%. A chi square analysis was performed to calculate the extinction percentage in Diablito. All the samples were included in the analysis. Ev ery species was classified as belonging to one of three categories and the extinction was calculated as the percentage of species occurring exclusively in the Cretaceous (K category) with respect to the number of species displaying non significant change across the boundary (KT cate gory), and the number of species in the K category. If all the species of pollen and spores are included in the analysis, the extinction percentage is 69%. If singletons (species occurring in only one sample) are removed from the analysis the percentage is 47%. This percenta ge is higher than the extinction percentage calculated for North America, suggesting that the change in vegetation was more severe in the

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84 tropics than in temperate latitudes. Is important to note that different approaches and methods have been used to calculate extinction leve ls making the comparison between studies more difficult. The changes in extinction between different places could be the result of the differences in the methodology used to calculate the extinction. The results of this study could support the hypothesis of a latitudinal extinction gradient, i.e. decreasing extinction with increasing latit ude (Wolfe and Upchurch, 1986; Upchurch, 1989). The patterns observed do not support the argument for attenuation of dama ge with increasing distance from the impact site (Nichols and Johnson, 2008). Diablito is located almost the same distance from the impact site as some of th e sections in North America (~4000km) and the effects in Diablito were higher. More sections of the KT boundary from the tropics are needed to test these hypotheses and to ma ke global generalizations.

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85 APPENDIX A PALYNOMORPH DISTRIBUTION IN SAMPLES FROM THE DIABLITO CORE Species FAD LAD # samples Achomosphaera sp. 1 2062.9 2062.9 1 Achomosphaera sp. 2 2244.4 2244.4 1 Achomosphaera sp. 3 1885.2 1885.2 1 Acritarcha 2018 1249.2 3 Andalusiella mauthei 1885.2 1517.5 2 Andalusiella spp. 2244.4 1727.1 2 Annutriporites iversenii 1965.5 1638.2 19 Apiculatasporites sp. 1731.8 1249.2 5 Apiculatisporites sp. 1 1849.4 1716.4 2 Apiculatisporites sp. 2 1506.7 1506.7 1 Araucariacidites sp. 2244.4 1565 15 Araucariacites australis 2244.4 1646 20 Arecipites sp. 1849.4 1849.4 1 Areoligera spp. 1550.5 1550.5 1 Ariadnaesporites spp. 2018 1633.8 4 Azolla spp. 1758.3 1758.3 1 Baculamonocolpites "amplius" 1732.1 1706 3 Baculamonocolpites "degradatus" 1752.9 1752.9 1 Baculamonocolpites "magnabaculatus" 1849.4 1849.4 1 Baculamonocolpites aff. multispinosus 2097.1 1672.8 7 Baculamonocolpites sp.1 1765.3 1765.3 1 Baculamonocolpites spp. 2097.1 1885.2 3 Baculatisporites "densinatus" 1849.4 1478.5 3 Baculatisporites "dual" 2018 1885.2 2 Baculatisporites "minor" 2244.4 2244.4 1 Baculatisporites "minutisimus" 931 794.7 2 Baculatisporites "perfectus" 1885.2 1885.2 1 Baculatisporites "reticularis" 1506.7 794.7 2 Baculatisporites sp. 2018 794.7 24 Baculatisporites sp.2 1941.4 1941.4 1 Baculatriletes "gemmatus" 1379 1379 1 Baculatriletes "minimus" 1707.7 1707.7 1 Baculatriletes sp. 1540.2 794.7 3 Bacumorphomonocolpites tausae 2018 2018 1 Bombacacidites "cortus" 1460.1 988.8 2 Bombacacidites aff. psilatus 1517.5 1506.7 2 Bombacacidites annae? 794.7 794.7 1 Bombacacidites sp. A 1018.5 988.8 2 Bombacacidites sp. B 1018.5 1018.5 1 Bombacacidites sp. C 1018.5 1018.5 1 Bombacacidites sp. D 896 794.7 3 Bombacacidites sp. E 950 950 1 Bombacacidites sp. G 931 931 1 Buttinia andrevi 2244.4 1638.2 2 Cerodinium diebelli 2018 2018 1

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86 Cerodinium pannuceum 2244.4 1941.4 4 Cerodinium sp. 2 2244.4 2244.4 1 Cerodinium spp. 2244.4 1638.2 5 Chomotriletes minor 2244.4 794.7 36 Cicatricosisporites "rugoides" 1601 1601 1 Cicatricosisporites sp. 1752.9 1752.9 1 Cicatricososporites "lofis" 1849.4 1478.5 2 Cingulatisporites sp.1 2097.1 2097.1 1 Cingulatisporites sp.2 2062.9 1478.5 2 Cingulatisporites sp.3 1478.5 1478.5 1 Clavainaperturites sp. 1707.7 1707.7 1 Clavamonocolpites "dispersus" 1646 1550.5 3 Clavatricolpites "disparis" 1438 1438 1 Clavatricolpites "minutidensiclavatus" 1179.6 794.7 5 Clavatricolpites densiclavatus 1614.6 1517.5 3 Clavatricolpites sp. 2097.1 2097.1 1 Clavatricolpites sp. 3 1696.3 1696.3 1 Clavatricolporites "baculatus" 1672.8 1635.7 2 Clavatriletes "magnicus" 1648.1 1648.1 1 Colombipollis tropicalis 2244.4 988.8 46 Concavissimisporites psilatus 1307.9 1307.9 1 Cordosphaeridium sp. 2244.4 1885.2 3 Corsinipollenites psilatus 1885.2 794.7 7 Corsinipollenites sp. 2244.4 858.2 2 Crassulina sp.1 1774.2 1574.1 3 Cricotriporites guianensis 1761.4 1646 3 Crusafontites grandiosus 2062.9 1849.4 5 Ctenolophonidites lisamae 1179.6 1179.6 1 Curvimonocolpites inornatus 1018.5 988.8 2 Cyclonephelium "fibrosum" 1849.4 1849.4 1 Cyclusphaera sp. 1965.5 950 2 Dinocyst und. 2244.4 931 15 Dinogymnium acuminatum 1821.5 1821.5 1 Dinogymnium sp. 1079.4 1079.4 1 Diporoconia cf. iszkaszentgyoergyi 1789.5 1641.3 2 Duplotriporites ariani 2097.1 1885.2 4 Echidiporites "docil" 1672.8 1672.8 1 Echimonocolpites "microechinataensis" 1550.5 1550.5 1 Echimonocolpites protofranciscoi 2244.4 1635.7 33 Echimonocolpites sp. 1599.5 858.2 5 Echimonocolpites sp. 2 2244.4 2244.4 1 Echimonoletes "gemmatus" 1941.4 1758.3 3 Echimonoletes sp. 1506.7 1179.6 3 Echimonoletes sp. 1 1638.2 1638.2 1 Echimonoletes sp. 2 2062.9 2062.9 1 Echimonoletes sp. 3 1696.3 1696.3 1 Echimonoletes sp. 4 1179.6 1179.6 1 Echimonoporites "specialis" 1672.8 1349.7 2 Echinatisporis "rojus" 2097.1 1400.6 9

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87 Echinatisporis sp. 2244.4 794.7 65 Echiperiporites? sp. 1965.5 1965.5 1 Echitricolporites sp. 1752.9 1752.9 1 Echitriletes "baculatus" 1941.4 1506.7 3 Echitriletes "densus" 1727.1 1727.1 1 Echitriletes "echinatus" 2244.4 2244.4 1 Echitriletes "gemmatus" 1765.3 1765.3 1 Echitriletes "intercolensis" 1970.7 1765.3 2 Echitriletes "papilospinosus" 1727.1 1727.1 1 Echitriletes "solaris" 1379 858.2 2 Echitriletes "spinosus" 1885.2 1849.4 2 Echitriletes sp. 1 2244.4 1379 6 Echitriletes sp. 3 2244.4 931 4 Echitriletes sp. 4 1356.8 1356.8 1 Echitriletes sp. 5 1527 1527 1 Echitriletes sp. 6 1626.2 988.8 4 Echitriletes spp. 2244.4 794.7 23 Echitriporites sp. 988.8 988.8 1 Echitriporites suescae 1991 1991 1 Echitriporites trianguliformis 2244.4 1179.6 62 Ephedripites "afropollensis" 2244.4 1672.8 6 Ephedripites "crucistriatus" 1758.3 1727.1 2 Ephedripites sp. 2062.9 1765.3 4 Ephedripites sp. 1 1849.4 1527 3 Ephedripites sp. 3 1574.1 1574.1 1 Ephedripites sp. 6 1849.4 1654.5 3 Foram linnings 2097.1 1540.2 10 Foveodiporites operculatus 1356.8 794.7 3 Foveodiporites sp. 931 931 1 Foveotricolpites perforatus? 931 858.2 2 Foveotricolpites sp. 1638.2 1638.2 1 Foveotricolporites sp. 1799.1 1647.4 2 Foveotriletes margaritae 2244.4 931 34 Gabonisporites vigourouxii 1849.4 1648.1 4 Gemmadiporites "diablensis" 1413.3 1349.7 2 Gemmamonocolpites "balonensis" 1761.4 1761.4 1 Gemmamonocolpites "megagemmatus" 1774.2 1774.2 1 Gemmamonocolpites "microgemmatus" 2018 1018.5 4 Gemmamonocolpites "minor" 1849.4 1706 2 Gemmamonocolpites "verrucatus" 794.7 794.7 1 Gemmamonocolpites dispersus 1965.5 1672.8 6 Gemmapollenites "difussus" 2062.9 2062.9 1 Gemmastephanocolpites gemmatus 1574.1 931 17 Gemmatisporis "densus" 1647.4 1249.2 2 Gemmatriletes "gemmatus" 1506.7 794.7 2 Gemmatriletes "granolaesuratus" 2018 1849.4 3 Gemmatriletes "indiferentis" 1565 1460.1 2 Gemmatriletes "scabratus" 950 950 1 Gemmatriletes spp. 1751.7 794.7 6

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88 Glaphyrocysta sp. 1 2244.4 2244.4 1 Hamulatisporis caperatus 1991 1641.3 14 Inaperturopollenites spp. 2244.4 1356.8 25 Ischyosporites sp. 1799.1 1799.1 1 L. proxapertitoides proxapertitoides 2244.4 896 42 L. proxapertitoides reticuloides 2062.9 1140.3 28 Laevigatosporites sp. 2244.4 794.7 51 Laevigatosporites sp. 1 1349.7 1249.2 2 Laevigatosporites sp. 2 1506.7 1506.7 1 Leiosphaera spp. 2097.1 1565 5 Longapertites "crassiperforatus" 1490.6 1490.6 1 Longapertites "echinatus" 1672.8 1506.7 2 Longapertites "minutifossulatus" 2018 2018 1 Longapertites marginatus 1506.7 931 6 Longapertites microfoveolatus 1400.6 794.7 9 Longapertites sp. 1 2097.1 1379 12 Longapertites vaneendenburgi 1752.9 931 14 Longitrichotomocolpites "microperforatus" 1550.5 1550.5 1 Longitrichotomocolpites sp. 1849.4 1574.1 5 Longitrichotomocolpites sp. 1 1641.3 1641.3 1 Magnastriatites "goleatus" 1991 931 3 Magnastriatites sp. 1727.1 1727.1 1 Margocolporites sp. 896 896 1 Mauritiidites franciscoi franciscoi 1179.6 794.7 11 Mauritiidites franciscoi var. pachyexinatus 931 858.2 2 Monocolpites "gigantispinosus" 2062.9 1672.8 7 Monocolpites "granulatus" 1750.5 1750.5 1 Monocolpites "verrucatus" 1965.5 1965.5 1 Monocolpites grandispinger 1991 1797.9 3 Monocolpites obtusispinosus 2062.9 1761.4 2 Monocolpites spp. 931 931 1 Monocolpopollenites "longiaperturado" 2062.9 896 6 Monocolpopollenites sp. 1970.7 1970.7 1 Monoporopollenites "foveolatus" 1849.4 1849.4 1 Monoporopollenites "microperforatus" 2244.4 2244.4 1 Monoporopollenites annulatus 1641.3 1018.5 5 Monoporopollenites sp. 1 1626.2 931 2 Odontochitina spp 1885.2 1885.2 1 Osmundacidites sp. 1490.6 1490.6 1 Palaeocystodinium sp. 2062.9 1885.2 3 Paleosantalaceaepites? sp. 1672.8 1672.8 1 Pediastrum spp. 2244.4 794.7 45 Perinomonoletes "acicularis" 1970.7 794.7 6 Perinomonoletes sp. 1885.2 1179.6 6 Periretisyncolpites giganteus 2097.1 1638.2 18 Periretisyncolpites giganteus var. minor 1249.2 1179.6 2 Polypodiaceoisporites "trilobatus" 1672.8 1672.8 1 Polypodiaceoisporites sp. 1 1517.5 1517.5 1 Polypodiaceoisporites sp. 2 1527 794.7 2

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89 Polypodiaceoisporites sp. 3 1614.6 1614.6 1 Polypodiaceoisporites sp. 5 896 896 1 Polypodiaceoisporites spp. 1614.6 896 4 Polypodiisporites sp. 1 1727.1 1727.1 1 Polypodiisporites sp. 2 1641.3 1641.3 1 Proteacidites dehaani 2097.1 1672.8 21 Proxapertites "gemmatus" 2244.4 1647.4 8 Proxapertites "sulcatus" 2097.1 1672.8 5 Proxapertites aff. "minutihumbertoides" 1941.4 1672.8 2 Proxapertites cursus 1018.5 794.7 2 Proxapertites humbertoides 1970.7 950 3 Proxapertites magnus 988.8 794.7 4 Proxapertites operculatus 2244.4 794.7 63 Proxapertites operculatus var. "reptilatus" 2062.9 1179.6 8 Proxapertites psilatus 2097.1 896 60 Proxapertites tertiaria 1991 931 2 Proxapertites verrucatus 1970.7 1638.2 12 Psilabrevitricolporites "circularis" 1249.2 1249.2 1 Psilabrevitricolporites "marginatus" 2018 2018 1 Psilabrevitricolporites "scabratus" 1249.2 1249.2 1 Psilabrevitricolporites simpliformis 1249.2 794.7 6 Psilabrevitricolporites sp. 1 1965.5 1965.5 1 Psilabrevitricolporites sp. 2 1605.8 1605.8 1 Psilabrevitricolporites sp. 3 1648.1 1648.1 1 Psilabrevitricolporites spp. 2097.1 1249.2 8 Psiladiporites sp. 1 1970.7 1550.5 6 Psiladiporites sp. 2 794.7 794.7 1 Psilamonocolpites "donensis" 1648.1 1648.1 1 Psilamonocolpites medius 2244.4 794.7 82 Psilamonocolpites operculatus 1965.5 794.7 13 Psilastephanocolpites "singularis" 1885.2 1821.5 3 Psilastephanocolpites sp.2 1249.2 1249.2 1 Psilastephanocolporites "ocularis" 1672.8 1672.8 1 Psilastephanocolporites "operculoverrucatus" 1751.7 1751.7 1 Psilastephanocolporites"syncolpatus" 1646 1646 1 Psilastephanoporites sp.1 1941.4 1849.4 2 Psilasyncolporites sp. 1638.2 988.8 2 Psilasyncolporites sp. 2 1626.2 1626.2 1 Psilatricolpites "arrowensis" 1849.4 1641.3 10 Psilatricolpites sp. 1 1821.5 1758.3 2 Psilatricolpites sp. 2 1849.4 1849.4 1 Psilatricolpites sp. 3 2062.9 1648.1 4 Psilatricolpites spp. 1774.2 988.8 6 Psilatricolporites "ampliexinatus" 1965.5 1750.5 4 Psilatricolporites "annulomarginatus" 1490.6 1490.6 1 Psilatricolporites "apendicatus" 1965.5 1965.5 1 Psilatricolporites "diablensis" 1991 1991 1 Psilatricolporites "grandis" 1646 1646 1 Psilatricolporites "marginalis" 1849.4 1849.4 1

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90 Psilatricolporites "poriannulatus" 1787.2 1787.2 1 Psilatricolporites sp.1 1638.2 1638.2 1 Psilatricolporites spp. 2062.9 794.7 27 Psilatriletes "arcuatus" 1506.7 1506.7 1 Psilatriletes < 25 2244.4 794.7 39 Psilatriletes > 50 2244.4 931 24 Psilatriletes 25-50 2244.4 794.7 82 Psilatriporites "minor" 1638.2 1638.2 1 Psilatriporites sp. 2 1849.4 1400.6 5 Psilatriporites sp. 3 1849.4 1849.4 1 Pteridacidites sp. 1 1018.5 1018.5 1 Pteridacidites sp. 2 931 931 1 Racemonocolpites racematus 2018 1356.8 13 Racemonocolpites sp. 2244.4 1506.7 8 Racemonocolpites sp. 2 1249.2 1249.2 1 Retibrevitricolporites "microperforatoides" 1941.4 1941.4 1 Retibrevitricolporites sp. 1 1787.2 1574.1 4 Retidiporites "elongatus" 1849.4 1638.2 5 Retidiporites "fossulatus" 1672.8 1672.8 1 Retidiporites "foveolatus" 1356.8 1356.8 1 Retidiporites "microperforatus" 2244.4 1706 9 Retidiporites magdalenensis 1356.8 794.7 12 Retidiporites sp. 1672.8 1605.8 2 Retidiporites sp. 2 1356.8 931 2 Retimonocolpites "gradatus" 2244.4 2244.4 1 Retimonocolpites "operculatus" 1885.2 1672.8 2 Retipollenites "afropollensis" 1706 1706 1 Retistephanocolpites sp. 1605.8 1605.8 1 Retistephanocolporites "ecuatorialis" 1307.9 1179.6 3 Retitrescolpites sp. 1 1885.2 1797.9 3 Retitricolpites "fortii" 1672.8 1672.8 1 Retitricolpites "minor" 1646 1646 1 Retitricolpites "reticularis" 1885.2 858.2 5 Retitricolpites "triangulatus" 1970.7 1970.7 1 Retitricolpites aff. "microreticulatus" 1991 1991 1 Retitricolpites spp. 1797.9 1647.4 2 Retitricolporites "ampliporatus" 1965.5 1752.9 2 Retitricolporites "finitus" 931 931 1 Retitricolporites "fossulatus" 2062.9 1970.7 2 Retitricolporites "gradatus" 1849.4 1849.4 1 Retitricolporites "marginatus" 1991 1638.2 2 Retitricolporites "minutus" 1941.4 1641.3 2 Retitricolporites sp. 1 1672.8 1672.8 1 Retitricolporites sp. 2 1647.4 1647.4 1 Retitricolporites sp. 4 1506.7 1506.7 1 Retitricolporites sp. 5 1018.5 1018.5 1 Retitricolporites spp. 2244.4 794.7 52 Retitriletes "bolonensis" 2244.4 2244.4 1 Retitriletes "cingulatus" 2244.4 2244.4 1

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91 Retitriletes "claris" 1727.1 1727.1 1 Retitriletes "minutus" 2244.4 1478.5 25 Retitriletes "verrucatus" 1506.7 1506.7 1 Retitriletes sp. 1799.1 1799.1 1 Retitriletes sp. 1 1941.4 1821.5 2 Retitriletes sp. 2 1731.8 1478.5 3 Retitriletes sp. 4 896 896 1 Retitriletes sp. 5 1761.4 1761.4 1 Retitriporites "spinosus" 1849.4 1849.4 1 Retitriporites sp.1 1965.5 1965.5 1 Retitriporites sp.2 1506.7 988.8 2 Rugomonocolpites "minoris" 1849.4 1849.4 1 Rugulatisporis "cerebroides" 1849.4 1849.4 1 Rugulatisporis sp. 1179.6 988.8 4 Rugulatisporites "rugulatus" 1941.4 1941.4 1 Rugulatisporites "tenuis" 1991 1991 1 Rugulatisporites sp. 1 1789.5 1789.5 1 Rugulatisporites sp. 2 1774.2 1732.1 2 Rugulatisporites sp. 3 931 931 1 Rugulatisporites sp. 4 2062.9 931 2 Rugulatisporites sp. 5 1727.1 1727.1 1 Rugulatisporites sp. 6 1849.4 988.8 2 Scabradiporites sp. 1752.9 1752.9 1 Scabrastephanocolporites "pachyexinataensis" 1849.4 1849.4 1 Scabrastephanoporites "sacabraporatus" 2062.9 2062.9 1 Scabratricolpites sp. 830.6 830.6 1 Scabratricolporites "psilatus" 1672.8 1672.8 1 Scabratriletes sp. 1638.2 794.7 4 Scabratriporites sp. 1349.7 1349.7 1 Senegalinium spp. 1970.7 1672.8 2 Spiniferites ramosus 1885.2 1885.2 1 Spiniferites sp. 2 1941.4 1941.4 1 Spiniferites spp. 2244.4 1550.5 7 Spinizonocolpites baculatus 2097.1 1638.2 34 Spinizonocolpites echinatus 1885.2 1751.7 5 Spirosyncolpites "gemmatus" 1112.2 1112.2 1 Stephanocolpites costatus 1991 1490.6 23 Striatopollis sp.1 1774.2 1774.2 1 Striatricolporites "specialis" 1774.2 1774.2 1 Striatricolporites perforatus 931 794.7 3 Striatricolporites sp. 2 950 896 2 Striatriletes sp. 1752.9 1752.9 1 Syncolpites "fossulatus" 1849.4 1849.4 1 Syncolporites aff. lisamae 1685.5 1249.2 2 Syncolporites lisamae 1799.1 1349.7 8 Syncolporites marginatus 1727.1 794.7 2 Syndemicolpites typicus 2097.1 1641.3 25 Terscissus canalis 1970.7 1179.6 5 Terscissus crassus? 1574.1 1574.1 1

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92 Terscissus sp. 1970.7 1356.8 4 Tetracolporites "annulatus" 1638.2 1478.5 2 Tetracolporites "operculoverrucatus" 1849.4 1849.4 1 Tetracolporites sp. 1799.1 1799.1 1 Tetracolporopollenites "duplex" 1672.8 1672.8 1 Tetracolporopollenites "perforatus" 1758.3 1671 5 Tetracolporopollenites aff. transversalis 1758.3 1638.2 4 Tetracolporopollenites sp.4 1970.7 931 4 Tetracolporopollenites spp. 1941.4 794.7 15 Tetradites sp. 1885.2 1647.4 2 Tetradites sp. 2 1648.1 1648.1 1 Tetradites umirensis 2062.9 1641.3 2 Thalassipora sp. 2097.1 2097.1 1 Tricolpites aff. microreticulatus 1758.3 1758.3 1 Tricolpites sp.1 1970.7 1970.7 1 Tricolpites sp.2 1614.6 1614.6 1 Tricolpites sp.3 1018.5 1018.5 1 Triporopollenites sp. 794.7 794.7 1 Trithyrodinium sp. 2062.9 2062.9 1 Ulmoideipites krempii 1991 794.7 20 Verrubrevitricolporites sp. 1685.5 1641.3 3 Verrucatosporites sp. 1 1765.3 1672.8 2 Verrucatosporites sp. 2 1727.1 1727.1 1 Verrucatosporites sp. 3 2097.1 2097.1 1 Verrucatotriletes "discretus" 1991 1991 1 Verrucatotriletes sp. 2 1716.4 931 4 Verrucatotriletes sp. 3 2244.4 794.7 6 Verrucatotriletes sp. 4 2018 1527 3 Verrucatotriletes spp. 2244.4 794.7 6 Verrutriletes "magnoviruelensis" 2062.9 950 9 Verrutriletes "viruelensis" 2244.4 794.7 44 Verrutriporites sp. 1751.7 1751.7 1 Zlivisporis "gibraltarensis" 1849.4 950 2 Zlivisporis blanensis 2244.4 1249.2 22

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93 APPENDIX B ILUSTRATION OF PALYNOMORPHS 1 Annutriporites iversenii 2 Terscissus canalis 3 Hamulatisporis caperatus 4 Crusafontites grandiosus 5 Diporoconia cf. diporoconia iszkaszentgyoergyi 6 Spinizonocolpites echinatus 7 Duplotriporites ariani 8 Azolla spp 9 Racemonocolpites racematus 10 Perinomonoletes acicularis 11 Proteacidites dehaani 12 Periretisyncolpites giganteus 13 Psilabrevitricolporites simpliformis 14 Ulmoideipites krempii 15 Corsinipollenites psilatus 16 Ctenolophonidites lisamae 17 Echimonocolpites protofranciscoi 18 Foveotriletes margaritae 19 Longapertites vaneendenburgi 20 Zlivisporis blanensis

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102 Sepkoski, J. 1990. The taxonomic structure of peri odic extinction. Geological society of America Special Paper 247:33-44. Shannon, C. E. 1948. A mathematical theory of comunication. Bell System Technical Journal 27. Shaw, A. B. 1964. Time in Stratigraphy. McGraw-Hill, New York. Short, N. M. 1968. Petrographic study of shocked rocks from the Steen River structure, Alberta. Pp. 185-210. In B. M. French, Short, N.M, ed. Shock metamorphism of natural materials. Simons, B. G., B. 2004. Spherule Layers-Records of Ancient Impacts. Annu. Rev. Earth Planet. Scie 32:329-61. Smith, J., Hertogen, J. 1980. An extraterrestrial event at the Cretaceous-Tertiary boundary Nature 285:198-200. Sneath, P. H., Sokal, R.R. 1973. Numerical Taxon omy: The principles and Practice of Numerical Classification. W.H. Freeman and Co. Sole de Porta, N. 1971. Algunos generos nuevos de polen procedentes de la Formacion Guaduas (Maastrichtiense-Paleocene) de Colombia. Studia Geologica 2:133-143. Sole de Porta, N. 1972. Palinologia de la Form acion Cimarrona (Maastrichtiense) en el valle medio del Magdalena, Colombia Studia Geologica 4:103-142. Sorensen, T. 1948. A method of establishing groups of equel amplitude in plant sociology based on similarity species content and its application to analyses of the vegetation on Danish commons. Biologsike Skrifter 5:1:34. Stinnesbeck, W., Schulte, P., Lindenmaier, F., Adatte, T., Affolter, M., Schilli, L., Keller, G., Stuben, D., Berner, Z., Kramar, U., Burns, S., Lopez-Oliva J. 2001. Late Maastrichtian age of spherule deposits in northeastern Mexico : implication for Chicxulub scenario. Can. J. Earth Sci 38:229-238. Swisher, C. C., Grajales-Nishimura, J., Montanari, A., Margolis, S.V., Claeys, P., Alvarez, W., Renne, P., Cedillo-Pardoa, E., Maurrasse, F.J., Curtis, G.H., Smit, J., McWilliams, M. 1992. Coeval 40Ar/39Ar ages of 65.0 Million years ago from Chicxulub crater melt rock and Cretaceous-Tertiary boundary tektites. Science 257:954-958. Traverse, A. 1996. Nomenclature and Taxonomy: Sy stematics, a rise by any other name would be very confusing. Pp. 11-28. In a. D. G. J. Jansonious, ed. Palynology: principles and applications. AASP Foundation, Tulsa, OK. Tschudy, R. H., Pillmore, C., Orth, C., Gilmore, J., Knight, J. 1984. Disruption of the terrestrial Plant Ecosystem at the Cretaceous-Tertiary boundary, Western Interior. Science 225:10301032.

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103 Vajda, V., Raine,J.I., Hollis, C.J. 2001. Indication of Global deforestation at the CretaceousTertiary boundary at New Zealand fern spike. Sciende 294:1700-1701. Van der Hammen, T. 1958. Estr atigrafia del Terciario y M aestrichtiano continentales y tectonogenesis de los Andes Colombianos. Ibid 6(1-3):67-128. Van der Hammer, T. 1954a. El desarrollo de la fl ora Colombiana en los periodos Geologicos. 1Maestrichtiano hasta Terciario mas inferi or. (Una investigacion Palinologica de la Formacion Guaduas y equivalentes). Boletin Geologico II(1):49-106. Van der Hammer, T. 1954b. Principios de la nomenclatura palinologica sistematica. Boletin Geologico 2(2):3-24. Van der Hammer, T. 1956a. A Palynological Syst ematics Nomenclature Boletin Geologico IV(2-3):63-101. Van der Hammer, T. 1956b. Descripcion de algunos generos especiales de polen y esporas fosiles. Boletin Geologico 4(2-3):103-109. Van der Hammer, T. 1958. Estratigrafia del Terciario y Maestrichtiano continentales y tectonogenesis de los Andes Colombianos. Ibid 6(1-3):67-128. Van der Hammer, T., Wymstra, T.A. 1964. Pa lynological study of the Tertiary and upper Cretaceous of British Guiana. Leidse Geol. Meded 30:183-241. Van der Hammer, T. 1966. The Paleocene polle n flora of Colombia. Leidse Geol. Meded 35:105-116. Van der Kaars, W. 1983. A Palynological-Paleoecol ogical study of the lower Tertiary coalBed sequence from El Cerrejon (Colombi a). Geologia Norandina 30:33-48. Villamil, T. 1999. Campanian-Miocene tectonostr atigraphy, depocenter evolution and basin development of Colombia and western Venezu ela. Palaeogeography, Palaeoclimatology, Palaeoecology 153:239-275. Weng, C., Hooghiemstra, H., Duivenvoorden, J. 2006. Challenges in estimating past plant diversity from fossil pollen data: statistical assessment, problems, and possible solutions. Diversity and Distributions 12:310-318. Wilf, P., and Johnson, K.R. 2004. Land plant extinctionat the end of the Cretaceous: a quantitative analysis of the North Dakota megafloral record. Paleobiology 30:347-68. Wing, S. L., Alroy, J., Hickey, J.L. 1995. Plant and mammal diversity in the Paleocene to Early Eocene of the Bighorn Basin. Palaeogeogr aphy, Palaeoclimatology, Palaeoecology 115:117-155. Wolfe, J., Upchurch, G.R. 1986. Vegetation, c limatic and floral changes at the CretaceousTertiary boundary. Nature 352:420-423.

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104 Wolfe, J. A. 1990. Paleobotanical evidence fo r a marked temperature increase following the Cretaceous-Tertiary boundary. Nature 343:153-156. Wolfe, J. A. U., G.R. 1986. Vegetation, climatic and floral changes at the Cretaceous-Tertiary boundary. Nature 324:148-152. Yeager, D. P., Ultsch, G.R. 1989. Physiological regulation and conformation: a BASIC program for determination of critical points. Physiol. Zool 62:888-907. Yepes, O. 2001. Maastrichtian-Danian Dinofla gellate Cyst Biostratigraphy and Biogeography from two Equatorial sections in Colombia and Venezuela. Palynology 25:218-252. Zachos, J., Pagani, M., Sloan, L., Thomas, E., Billups, K. 2001. Trends, Rhythms, and Aberrations in Global Climate 65 Ma to Present. Science 292:686-693. Zachos, J. C., Arthur, M.A. 1986. Paleoceanography of the Cretaceous/Tertiary boundary event: Inferences from stable isotopic and other data. Paleoceanography 1:5-26. Zhang, T. 2000. Artificial Intelligence models for Quantitative Biostratigraphy. University of Illinois, Chicago.

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105 BIOGRAPHICAL SKETCH Felipe de la Parra was born in Bogota, Colomb ia. The youngest of three children, he grew up mostly in Bogota, graduating from Colegio Ca fam in 1996. He earned his B.S in geology and his M.S in geology from the Universidad Naciona l de Colombia and University of Florida, respectively. Upon graduating in December 2001 with his B.S. in geology, Felipe entered to the Instituto Colombiano del Petroleo to work as a ju nior palynologist. Then he moved to Panama to work in the Smithsonian Tropical Research Institute. Upon completion of his MS program is spring 2009, Felipe will be working in th e Instituto Colombiano del Petroleo.



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1 PALYNOLOGICAL CHANGES ACROSS THE CRETACEOUS-TERTIARY BOUNDARY IN COLOMBIA, SOUTH AMERICA By FELIPE DE LA PARRA A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA

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2 2009 2009 Felipe de la Parra

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3 To my mom, Nicolas and Mariana

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4 TABLE OF CONTENTS page LIST OF TABLES................................................................................................................. .....6 LIST OF FIGURES................................................................................................................ ....7 ABSTRACT....................................................................................................................... ........9 CHAPTER 1 INTRODUCTION .............................................................................................................11 Previous Palynological Studies of the KT Boundary in Colo mbia .......................................15 Biostratigraphy of the KT Boundary in Colomb ia.............................................................. 17 2 OBJECTIVES................................................................................................................... .27 3 GEOLOGY AND STRATIGRAPHIC FRAMEWORK .....................................................28 Regional Geology..............................................................................................................2 8 Litostratigraphy and Depos itional Envir onment ..................................................................28 Molino Formation..............................................................................................................2 9 Barco Formation................................................................................................................ 29 4 MATERIALS.................................................................................................................... .33 5 METHODS ........................................................................................................................37 Diversity Pattern thr ough the KT Boundary ........................................................................ 37 Richness and Rarefaction...................................................................................................37 Shannon-Wiever Inde x ...................................................................................................... 38 Range Through Method ...................................................................................................... 38 Standing Diversity............................................................................................................. .39 Edge Effect and Piecewise Analysis ...................................................................................39 Graphic Correlation an d Taxonomic Rates ......................................................................... 40 Cluster Analysis............................................................................................................... ..42 Extinction Percentages.......................................................................................................43 6 RESULTS...................................................................................................................... ....46 Detecting the KT Bounda ry................................................................................................ 46 Magnetic Sus ceptibility .....................................................................................................48 Diversity Pattern Thr ough the KT Boundary ...................................................................... 50 Richness and Rarefaction...................................................................................................51 Shannon I ndex .................................................................................................................. .52 Standing Diversity............................................................................................................. .53

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5 Changes in Composition.....................................................................................................53 Taxonomic Rates................................................................................................................ 54 Extinction Percentages.......................................................................................................55 7 DISCUSSION................................................................................................................... .76 APPENDIX A PALYNOMORPH DISTRIBUTION IN SAMPLES FROM THE DIABLITO CORE .......85 B ILUSTRATION OF PALYNOMORPHS ...........................................................................93 LIST OF REFERENCES..........................................................................................................96 BIOGRAPHICAL SKETCH...................................................................................................105

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6 LIST OF TABLES Table page 1-1 Palynomorph species shared by the Di ablito and Sutataus a sections ..............................26 5-1 Equations to calculate mean standing diversity and per capita extinction (q) and origination (p) ra te.........................................................................................................45 6-1 Lithology of samples with high magnetic susceptib ility valu es......................................73 6-2 First (FAD) and Last (LAD) appearance datums for taxa used in the graphic correlation. ................................................................................................................. .74 6-3 Number of species per bin in each one of the Foote’s taxa categories. ............................75

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7 LIST OF FIGURES Figure page 1-1 Map showing the locations of the KT bounda ry sections with c ontinental record ...........24 1-2 Palynological zonation pr oposed by Germ eerad ............................................................24 1-3 Palynological zonation proposed by Muller ..................................................................25 1-4 Palynological zonation of the Cretaceous -Tertiary boundary interval in the ChecuaLenguazaque section......................................................................................................25 3-1 General stratigraphic column of Diablito .......................................................................31 3-2 Stratigraphic column of the interval where the KT boundary is locat ed..........................32 4-1 Location of Diab lito. ...................................................................................................... 36 5-1 Four fundamental classes of taxa present in each stratigraphic interval. .........................45 6-1 Stratigraphic distribution and a bundance of typical Cretaceous taxa. .............................57 6-2 Histogram of the number of LADs.................................................................................57 6-3 Graphic showing LAD and FAD of species that disappear between 1600’ and 1800’.....58 6-4 Histogram of the number of samples where the species with LAD between 1600’ and 1800’ were record ed. ..................................................................................................... 58 6-5 Magnetic susceptibility pattern found in five different sections of the KT boundary .......59 6-6 Magnetic susceptib ility in Di ablito ................................................................................60 6-7 Magnetic susceptibility of the KT boundary interval in Diab lito.. .................................. 61 6-8 Number of species (S) vs. Depth in Diablito ..................................................................61 6-9 Normal QQ plot of the mean number of species in the Cretaceous and the Paleocene....62 6-10 Rarified richne ss at 100 gr ains.. .....................................................................................63 6-11 Shannon index. ............................................................................................................ ..64 6-12 Normal QQ plot of the mean Shannon i ndex of the Cretaceous and the Paleocene.. .......65 6-13 Boxplot of the Shannon index for the Cretaceous and the Paleocene. .............................66 6.14 Standing diversity using range-through method. ............................................................67

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8 6-15 Standing diversity using range-thr ough method without singlet ons ................................68 6-16 Cluster analysis of the samples......................................................................................69 6-17 Graphic correlation. Diab lito vs. Rio Lo ro. ..................................................................70 6-18 Per capita origination rate..............................................................................................7 1 6-19 Per capita extinction rate ............................................................................................... 71 6-20 Presence-absence distribution chart of pollen and spores recorded in Diablito................72 6-21 Number of species in each of the K, KT and P categories. .............................................72 6-22 Number of species in each of the K, KT and P categories excluding singletones.. ..........73

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9 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science PALYNOLOGICAL CHANGES ACROSS THE CRETACEOUS-TERTIARY BOUNDARY IN COLOMBIA, SOUTH AMERICA By Felipe de la Parra May 2009 Chair: M.R.Perfit Major: Geology The Cretaceous-Tertiary boundary (KT boundary) event is recognized as one of the major environmental crises of earth history. It is associated with significant extinctions of many groups. The palynological record from mid latitudes shows a dramatic and abrupt disappearance of many dominant taxa including the Late Cretaceous angi osperms at this boundary. An estimated loss of ~17-30% of palynomorph species has been seen throughout the western interior of North America, however not a single s ection has been studied palynologically in detail from the tropics and the effect of the KT boundary event on the ve getation of tropical low latitudes is not known. Were extinction percentages of tropical low latit ude vegetation greater than in middle latitude temperate communities? Did the palynofloral dive rsity change as a consequence of the KT boundary extinction event? To address these two questions, I studied 81 palynological samples across the KT boundary of a stratigraphic section in Cesar-Rancheria basin, Colombia, northern South America. Several techniques, including range th rough method, rarefaction, per-capita extinction and origination rates, and measures of taxonomic diversity were used to estimate extinction percentages and the changes in diversity associ ated with the boundary in low latitude tropical environments. There is extinction percentage of 48-70% associated with the KT boundary and a

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10 significant change in the rate of extinction. Origination rates do not seem to be affected. The analysis show a high diversity Cretaceous pa lynoflora suddenly replaced by a low diversity association that dominated during the Paleocen e. The results suggest important changes in neotropical floras across the KP boundary, far more intense than in temperate regions.

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11 CHAPTER 1 INTRODUCTION The history of life on Earth has been punctuated by several episodes of global change known as mass extinctions. These episodes are characterized by profound climatic and environmental changes that molded the history of life and the pace of evolution. One of these catastrophic events occurred 65 million years ago and is known as the Cretaceous-Tertiary boundary (KT boundary) event. In the marine realm, several groups of organisms such ammonites (Marshall, 1995), calcareous nannofossils (Gartner, 1995), planktonic foraminifera (Keller, 1995), inoceramid and rudistid bivalves (MacLeod et al., 1990) either became extinct or were drastically reduced to a fraction of their former diversity. On land, the most recognized group that became extinct were the non-avian dinosaurs and several other important groups of vertebrates showed a major decline in dive rsity and/or abundance (Archibald, 1995). The KT boundary episode was the focus of in tense debate for many years and several theories tried to explain the nature and cause of this mass extinction. In a gradualist scenario, long term global cooling and ma rine regression produced an acceleration of the background extinction (Officer & Drake, 1983, Hickey, 1981). In a catastrophic scenario, one or more extraterrestrial-driven environmental perturba tions were the main agents producing the mass extinction (Smith & Hertogen, 1980). In 1980, a team headed by Walter Alvarez (Alvarez et al, 1980) found strong evidence for what finally has been accepted as the cause of this cataclysm. In one section of the KT boundary located in Gubbio, Italy, Alvarez and his team found a thin clay layer enriched in the element Iridium which separates the Cretaceous from the Paleocene. Iridium is a rare element found only in very small amounts on the Earth, howev er it is very abundant in extraterrestrial bodies such as meteorites and asteroids. The iridium enrichment found at the KT transition links

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12 the impact of an extraterrestrial body to what happened 65 million years ago. Further discoveries of iridium anomalies in severa l marine and terrestrial KT boundary sections around the world have been discovered since Alvarez’s first discovery (Orth et al, 1981; Bohor et al., 1984; Nichols et al., 1986; Tschudy et al., 1984) supp orting the impact theory. The claystone that separates the Cretaceous from the Tertiary also contains an abundance of other mineralogical evidence for an extraterrestrial impact. Highly shocked terrestrial minerals (quartz, feldspar and zircon) that originated from rocks at the impact site (Morgan et al., 2006) have been found in terrestrial and marine sections of the KT boundary around the world. These shockmetamorphosed mineral grains show prominen t lamellar features (Bohor, 1987) occurring as multiple intersecting sets that are only known to be produced in three situations: rock associated with meteorite impact craters, nuclear bomb test sites, and high pressure laboratory explosive shock experiments (Short, 1968). Additional physical evidence of the impact includes microscopic spherules created by the condensation of melted silicate materials produced by the strike of the extraterrestrial object at cosmic velocities (Simons et al., 2004), anomalous amounts of rare elements (Izzet, 1990) and microscopic diamonds (Carlisle, 1992). This substantial, independent evidence supports the extraterrestrial impact theory as the cause of the KT boundary mass extinction. The crater produced by the impact was found one decade after the Alvarez team proposed the impact theory. Hildebrand et al. (1990), us ing magnetic and gravity field anomalies, discovered a 180-km diameter circul ar structure buried in the mi ddle of the Yucatan Peninsula, Mexico. The stratigraphy of this structure, called Chicxulub, revealed a sequence of andesitic igneous rocks interbedded with glass and breccias that contain evidence of shock metamorphism (Hildebrand et al., 1990). The chemical and isotopic composition of the sequence found in the

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13 crater is similar to those of deposits found in KT boundary sections. 40Ar/39Ar dating of core samples recovered from the impact breccia contained within the subsurface Chicxulub crater yielded a mean age of 64.98 0.05 million years (Swisher et al., 1992). The same age was also obtained for several KT boundary deposits around the world in conjunction with geochemical and petrological similarities suggesting that th e Chicxulub structure is the source for the spherules found at the KT boundary and is the KT boundary impact site. Subsequent analysis of samples taken from different KT boundary sites suggests that the body that impacted the Earth at the KT boundary was a CM2-type carbonaceous chondrite (Bottke et al., 2007). This type of asteroid is associated with what is now know as the Baptistina asteroid family, a cluster of fragments of a 170-km body that broke up between 190 and 140 million years ago in the main asteroid belt. According to Bottke et al. (2007), the collision between the Earth and a large fragment from the Baptistina asteroid shower 65 million years ago was the most likely cause of the KT mass extinction event. The impact produced many environmental pertur bations, including, among others, shifts in carbon cycle (Pierazzo et al, 1988), changes in precipitation and temperature (Wolfe, 1990), an increase in the CO2 dissolved in the sea, injection of sulfurous gases into the atmosphere (D’Hondt et al., 1998), temporary global darkness (Alvarez et al., 1980), global fires lasting for several months (Melosh et al., 1990), causing dras tic environmental and climatic changes that produced the collapse and reorganization of seve ral ecosystems and the extinction of marine (Kaiho & Lamolda, 1999) and terrestrial organisms (Orth et al., 1981; Tschudy et al., 1984). In sections deposited in terrestrial environments, the KT boundary has been detected by the coincidence of high concentrations of irid ium, the abrupt disappearance of certain pollen species (Nichols & Johnson, 2002; Bohor et al., 1984) and the presence of a low diversity fern

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14 assemblage at the beginning of the Paleocene. This so-called fern spike has been interpreted as the colonization of pioneer fern species in the aftermath of the KT crisis (Tschudy et al., 1984) The existence of this extinction level in ot her sections around the world (Braman et al., 1999; Vajda et al., 2001) indicates that several changes occurred within plant communities as a consequence of this environmen tal crisis. The palynological and megafloral record from mid latitudes show a dramatic and abrupt disappearance of most dominant taxa and nearly all of the late Cretaceous angiosperms following the KT bo undary. The basal Paleocene flora appears to be composed of taxa that were absent or ex tremely rare in the latest Cretaceous (Johnson & Hickey, 1990). An estimated loss of ~30-40% of palynomorph species has been seen throughout the western Interior of North America (Johnson et al., 1990). Palynofloral records from other places in the world (Hickey, 1981; Vajda & Raine, 2001) indicate that the effect of the KT boundary event was relatively minor in the southern hemisphere, suggesting a possible latitudinal extinc tion gradient, i.e decreasing extinction with increasing latitude (Wolfe & Upchurch, 1986). If this hypothesis were true, hi gh extinction levels would be expected in tropical areas. Howeve r, not a single section has been studied palynologically from the tropics (Figure 1-1) and the effect of the KT boundary on tropical vegetation is totally unknown. A clear understanding of the response of tropical vegetation to this environmental crisis is important to understand the effect of global cat astrophes on the vegetation and to compare the response of tropical vs. temperate vegetation to the same event. In the present study, palynomorph distribution across the Cretaceous-Tertiary boundary of one section located in the Cesar-Rancheria basin (northern Colombia) is studied. An analysis of

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15 diversity, extinction levels, ta xonomic rates and compositional changes through the boundary is presented. Previous palynological studies of the KT boundary in Colombia Using pollen and spores, Van der Hammen (1954a ), correlated the lower and middle part of the Guaduas Formation in the Eastern cord illera with the Umir Formation of the Lower Magdalena valley. Using amm onites and bivalves found by H ubach (1951), Van der Hammen (1954a) proposed a Maastrichtian age for the lo wer part of the Guaduas Formation and a Paleocene to lower Eocene age for the upper part of the Guaduas and Lisama Formation (lower Magdalena valley). During the Maastrichtian, the flora is largely dominated by angiosperms and primitive forms. Small changes in the numeric composition and some new species appear during the Maastrichtian and Van der Hammen (1954a) related these compositional changes to climate changes. A new type of flora found in the lower pa rt of the Lisama Formation and the upper portion of the Guaduas Formation is, accordi ng to Van der Hammen (1956b), the paleobotany evidence of the Cretaceous-Tertiary boundary. A co mplete change in the palynoflora with only few Cretaceous species seen in the Paleocene and an explosive radiation of new species is interpreted by Van der Hammen as the evidence of deep changes in the ecological conditions probably related to high Andean-alpine orogenic activity. Sole de Porta (1971) described several new genera and species from the Guaduas Formation and two assemblages be longing to the Cimarrona Forma tion, southern edge of the middle Magdalena valley (Sole de Porta, 1972). Acco rding to the foraminiferal association, the Cimarrona Formation is Maastrichtian in age. Th ere is no mention about the position, or the palynological changes across the KT boundary in these publications.

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16 Sarmiento (1992), studying one section of the Guaduas Formation lo cated in Sutatausa (northern Bogota), found 79 palynomorphs, 33 of which are new species. He proposed eight new genera and six new combinations. Based on the stratigraphic distribution of palynomorphs found in 61 samples, he divides the section in two z ones and subdivides the upper zone in to two sub zones. The Cretaceous-Tertiary boundary in the Sutatausa section is according to Sarmiento located between the zones one and two. Some of the criteria that he used to locate the KT boundary are: 1. A foraminifera association similar to those found by Martinez (1987) in the CesarRancheria basin (northen Colombia), indicating a late Masstrichtian age for the base of the Guaduas Formation. 2. Tropical cosmopolitan dynoflagellates (eg. Dinogymnium acuminatum), reported to persuit until the late Maastrichtia n, were found only in zone one. 3. Disappearance of palynomorphs close to the boundary between zones one and two. However, some of these species are found again in the middle of zone two. 4. The first occurrence of new species is, according to Sarmiento, one of the most important pieces of evidence to identify the KT boundary. Most of the first occurrences are found at the boundary between the two zones, however so me of them are found some meters below. 5. A paleocanal filled in its lowest part by fine carbonaceous material, well preserved organic matter, fossil leaves, teeth and phosphate nodul es. Overlying this sequence, a carbonaceous level with some fragments of vertebrates and teeth and the uppe r part of the channel filled by fine-grain sediments and some concretionary levels. According to Sarmiento, this could be the result of a catastrophic event associated with regional changes at the end of the Cretaceous. In summary, previous palynological studies of Cr etaceous and Paleocene sediments in Colombia suggested drastic changes in the vegetation at the end of the Cretaceous. Although the nature of these changes were not clear at the time that th e works were published, the palynological record was strong enough to show the importance of this transition. The nature and quantification of the changes at the KT boundary were probably beyond th e scope of these previous studies and are still elusive.

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17 In the present study, the palynomorph distribution across one section of the KT boundary in Colombia is presented to assess the changes in plant composition and diversity through the boundary and to calculate the palynological extinct ion percentages associated with the boundary. Biostratigraphy of the KT boundary in Colombia Continental sections of the KT boundary in th e Western Interior of North America have been associated with the extin ction of typical Cretaceous speci es of palynomorphs (Nichols & Johnson, 2002) and the existence of a “fern spike” that could represent colonization by pioneer species in the aftermath of the KT boundary cris is (Tschudy, 1984). The change in the vegetation has also been associated with physical eviden ce of the impact (shocked quartz, spherules and high concentrations of iridium and other rare elements) and evidence of environmental and climate change (alteration of the carbon cycle) th at links the changes observed in the vegetation with the event at the KT boundary. In this sense, palynology has been shown to be one of the most important tools to identify and locate the KT boundary precisely in continental sections from the western interior of North America. The disappearance of typical Cretaceous palynomorphs is a reliable indicator of the position of the KT boundary. Studies based on pollen and spores in Cretaceous and Paleocene sediments in Colombia and Venezuela (Pocknall et al., 1997; Sarmiento, 1992) have shown that an important proportion of palynomorphs recorded in Cretaceous sediments are absent in the Paleocene. This observation suggests that palynology could be used in tropica l sections to detect the KT boundary and the evidence associated with this event. However, only a few palynological zonations have been proposed for the Cretaceous-Tertiary transition in Colombia (Germeraad et al., 1968; Muller, 1987; Sarmiento, 1992). Germeraad et al. (1968) used several secti ons from tropical South America, Africa and Asia, to establish a broad palynological zonation on a pantropical scale that is further subdivided

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18 regionally (Figure 1-2). One pantropical zone ranging from the Maastrichtian to the middle Eocene ( Proxapertites operculatus zone), is proposed. This zone is characterized by the cooccurrence of Proxapertites operculatus Proxapertites cursus Spinizonocolpites echinatus and Echitriporites trianguliformis (Germeraad et al., 1968). The pantropical Proxapertites operculatus zone is subdivided in the Caribbean area in to three zones (Germeraad et al., 1968) (Figure 1-2): The Proteacidites dehaani zone, Retidiporites magdalenensis zone and Retibrevitricolpites triangulatus zone. The P. dehaani zone is characterized by the co-occurrence of P. dehaani and Buttinia andreevi and important percentages of F. margaritae (Germeraad et al., 1968). The boundary with the overlying Retidiporites magdalenensis zone marks the last appearance datum (LAD) of P. dehaani, Buttinia andreevi and the co-occurrence of R. magdalenensis Echitriporites trianguliformis and P. operculatus In the Caribbean area, the boundary between the Maastrichtian and the Dani an is located in the boundary between the Proteacidites dehaani and the Foveotriletes margariate zones (Figure 1-2). The F. margaritae zone is characterized by the co-occurrence of Stephanocolpites costatus Foveotriletes margaritae Longapertites vaneendenburgi Gemmastephanocolpites gemmatus and by the absence of Bombacacidites annae and Ctenolophonidites lisamae (Germeraad et al., 1968). Although the work of Germeerad et al. (1968) is based on numerous sources of information, their scope is regional and it is very difficult to es tablish useful biostratigraphic events (last appearances or first appearances) with enough stratigraphic resolution to identify the KT boundary. Muller et al. (1987) produced a refined versi on of the zonation proposed by Germeerad et al. (1968) by using information from different sed imentary basins in Venezuela. Three zones for the Maastrichian and three zones for the Paleocene are defined by Muller et al. (1987) (Figure 1-

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19 3). The boundary between the Maastrichtian an d the Paleocene is marked by the boundary between the Proteacidites dehaani and Spinizonocolpites baculatus zones. The base and top of the Proteacidites dehaani zone (zone 13) is defined by the first appearance datum (FAD) of Proteacidites dehaani and Spinizonocolpites baculatus respectively. The LAD of Foveotriletes margaritae Stephanocolpites costatus Proxapertites operculatus and Ulmoideipites characterize the base of the zone. The LAD of Buttinia andreevi Proteacidites dehaani Crassitricolporites brasiliensis Aquilapollenites and Scollardia characterizes the top of the zone. The base of the Spinizonocolpites baculatus zone (zone 14) is defined by the FAD Spinizonocolpites baculatus and the FAD of Gemmastephanocolpites gemmatus and the LAD of Spinizonocolpites baculatus define the top. The zone is also recording the FAD of Bombacacidites Mauritiidites franciscoi and is, in accordance with Muller et al. (1983), poor in ferns and gymnosperms. Most of the species that Muller et al. (1987) used for the zonation are not present in Colombia (e.g. C. brasiliensis, Crassitricolporites subprolatus, A. reticularis ) making their use difficult in other sedimentary basins. Also, the Campanian-Maastrichtian boundary was recently modified (Grandstein et al., 2005) and foraminifera zones that in the past were considered as Maastrichtian, now corresp ond to upper Campanian. This is probably the case of the Muller et al. (1987) zonation, indica ting that species that had been considered Maastrichtian could in fact be from the upper Campanian. Probably the most important work related to the KT boundary in Colombia using pollen and spores is that of Sarmiento (1992), who studi ed one section located in the western flank of the Checua-Lenguazaque syncline. Sarmiento (1992a) proposed two informal zones and subdivided the upper zone in to two subzones (Figure 1-4).

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20 The Buttinia andrevii zone (zone I) is characterized by the LAD of Echimonocolpites echiverrucatus, Spinizonocolpites echinatus, Re timonocolpites claris, Crusafontites grandiosus, Clavatriletes mutisi, Inaperturapllen ites cursis, Psilamonocolpites ciscudae and Retitricolporites belskii. Other important palynomor phs in zone 1 include Buttinia andrevii Ulmoidipites krempii and Zlivisporis blanensis which are abundant and frequent and although they disappear at the top of this zone, they are found again in zone II (Sarmiento, 1992a) (Figure 1-4). According to Sarmiento (1992), zone I corresponds to the “ Proteacidites dehaani zone” of Germeraad et al. (1968) and the “zone 13” of Muller et al. (1987) The relation between zone I of Sarmiento and the “ Proteacidites dehaanii ” zone of Germeraad et al. (1968) is based more on stratigraphic position than on palynological content (Sarmiento, 1992). The “Fovetriletes margaritae” zone (zone II) is characterized by the first appearance of 28 species, dominance of Angiosperms and Palms, and low presence of ferns (Sarmiento, 19 92). The zone is subdivided in two informal subzones: Subzone “II-A” (“ Zonotricolpites variabilis ” zone) and subzone “II-B” (“ Syncolporites lisamae ” zone) (Figure 1-3). The FAD of several species that have a wider dispersal and frequency in zone II-A is recorded below the boundary between zones “I” and zone “II”. For this reason the boundary between the tw o zones is regarded by Sarmiento (1992) as gradual. These species are: Proxapertites psilatus, Gemmamonocolpites dispersus, Crassitricolporites costatus, Syndemicolp ites typicus, Foveotriletes magaritae, Psilabrevitricolpites marginatus, Psilatr icolpites microverrucatus, Longapertites vaneendenburgi, Racemonocolpites racematus. Some of the species recognized by Sarmiento (1992a) with FAD at the boundary between zones “I” and “II” are: Longapertites perforatus Psilabrevitricolporites annulatus Mauritiidites franciscoi Zonotricolpites variabilis and Rugotricolpites oblatus Species having their FAD a few me ters above the boundary between

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21 zones “I” and “II” are: Echimonocolpites coni, Retibrevitricolp ites cf. inciertus, Retitricolporites exinamplius, Scabratricolpites thomasi, In certirrugulites carbonensis and Proxapertites operculatus. Finally, species having their FAD in the middle or the top of the subzone “II-A” are: Retitricolpites minutus, Retim onocolpites regio, Incertisc abrites pachoni, Zonotricolpites lineaus, Retimonocolpites retifosulatus, Striat ricolpites minor, Proxapertites verrucatus and Scabratriletes globulatus. Subzone II-B is characterized by the disappearance of 25% of the palynoflora (Sarmiento, 1992). Species with LAD in this zone include: Duplotriporites ariani, Bacumorphomonocolpites tausae, Ephedripites multicostatus, Araucariacites australis, Scabrastephanocolpites guadensis Zlivisporis blanensis and the FAD of Syncolporites lisamae, Spinizonocolpites tausae and Psilatriletes martinensis (Figure 1-4). Changes in the abundance of other species are also seen in this subzone. According to this study, the KT boundary is placed in the boundary between zones II and I and is characterized by the LAD of at least eight species of palynomorphs and zone II is characterized by the disapp earance of at least 25% of the pal ynoflora. Some inc onsistencies were observed in the data from the Sarmiento’s work an d interpretations must be considered carefully. For example, Sarmiento stated that Retimonocolpites claris is one of the palynomorphs that is found exclusively in zone I and disappears belo w the boundary between zones II and I. However in table 2a (Sarmiento, 1992), which contains the information about palynomorph distribution through the section, the LAD of Retimonocolpites claris is in sample 273, which according to the stratigraphic column, shows the position of the samples and corresponds to 690-700 m. This depth is in the middle to upper part of subzone II-A (Figure 1-3). Another inconsistency found in this work, is the FAD of Syncolporites lisamae According to the text in Sarmiento (1992), the FAD of this species is one of the features of z one IIB, however in table 2a (Sarmiento, 1992), the

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22 FAD of Syncolporites lisamae is in sample 276, which corresponds to the middle to upper part of zone II-A (Figure 1-4). Finally, Zlivisporis blanensis, according to the text is one of the palynomorphs that disappe ars in zone II-B, but according to the information in table 2a (Sarmiento, 1992), the LAD of this species is in sample 285 which correspond to 715-720 m in the stratigraphic column and is included in z one II-A. The inconsiste ncies found between the information reported in the text and the informatio n recorded in the tables, makes it necessary to view the stratigraphic range of the palynomorphs reported by Sarmiento with caution. For this reason, a comparison of the biostratigraphic ranges between the two sections was not performed. To asses the similarity between the two sections, the Sorensen index was calculated (Sorensen, 1948). The complete association found in each section was taken as one sample and the sections were then compared. The Sorensen index ranges from 1.0, when two samples have the same species, to 0, when there are no species in common (Jaramillo, 2008). For the comparison, Sorensen (SI)= 2a / (2a +b +c), where, a= total number of species present in both samples, b=number of species present only in Di ablito and c=number of species present in the Sutatausa section (Sarmiento, 1992). The index i ndicates low similarity between the sections (SI= 0.14). Table 1.1 summarizes palynomorphs that are shared by both sections. The results of the Sorensen index suggest that the two sections have a very different palynological composition. Part of this difference could be explained by the fa ct that some of the species that were described as “informal” in Diablito could be some of the species reported in Sarmiento. A more detailed taxonomic work is necessary in Diablito as well as a direct comparison of the species found in both studies. In spite of this, it is clear that a high proportion of the species found in Dibalito are not recorded in the Sutatausa section (e.g. Cricotriporites

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23 guianensis Terscisus crassa Stephanocolpites costatus Curvimonocolpites inornatus among others), probably indicating endemism.

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24 Figure 1-1. Map showing the locations of the KT boundary sections with continental records (modified from Nichols and Johnson, 2008) Figure 1-2. Palynological zonation proposed by Germ eerad et al. (1968). 1) Pantropical zone; 2) Atlantic zone; 3) Caribbean zone.

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25 Figure 1-3. Palynological zonation proposed by Muller et al. (1987). Figure 1-4. Palynological zonation of the Cret aceous-Tertiary boundary interval in the ChecuaLenguazaque section (Sarmiento, 1992).

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26 Table 1-1. Palynomorph species shared by th e Diablito and Sutatausa sections (Sarmiento, 1992). Species Annutriporites iversenii Araucariacites australis Bacumormomonocolpites tausae Buttinia andreevi Colombipollis tropicalis Crusafontites grandiosus Duplotriporites ariani Echimonocolpites protofrancisoi Echitriporites trianguliformis Foveotriletes margaritae Gemmamonocolpites dispersus Longapertites vaneendenburgi Mauritidites francscoi franc. Periretisyncolpites giganteus Proxapertites humbertoides Proxapertites operculatus Proxapertites psilatus Proxapertites verrucatus Psilamonocolpites medius Racemonocolpites racematus Retidiporites elongatus Retidiporites magdalenensis Spinizonocolpites baculatus Spinizonocolpites echinatus Syncolporites lisamae Syncolporites marginatus Syndemicolpites typicus Tetradites umirensis Ulmoideipites krempii Zlivisporis blanensis

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27 CHAPTER 2 OBJECTIVES The aim of this study was to analyze the palynol ogical content of one section encompassing the Cretaceous-Tertiary boundary. The section is a rock core drilled in the Cesar-Rancheria basin (northern Colombia). Eighty-one samples through the core were analyzed. The main objectives of this study were: 1. To analyze the pattern of diversity through the Cretaceous-Paleocene boundary. 2. To calculate the palynological extinction level and compare this level with those found in other KT boundary sections in North America.

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28 CHAPTER 3 GEOLOGY AND STRATIGRAPHIC FRAMEWORK Regional Geology The latest Maastrichtian to early Paleocene stratigraphic record in Colombia and western Venezuela is the product of the infilling of an el ongated, very shallow mari ne to coastal basin, with three depositional systems delivering sediments from the east, west and south (Villamil, 1990). During the Maastrichtian, the central axis of deposition was located along the present day western foothills of the eastern Cordillera of Colombia. With the uplift of the ancestral Central Cordillera, the axis gradually shifted eastwards to a position along the central axis of the present day Eastern Cordillera and extended to the north to a position near to the present-day Maracaibo lake where it remained until the Paleocene (V illamil, 1990). The asymmetric flanks of the ancestral eastern Cordillera produced two different facies associations that are recorded in the west and east flank of the Central cordillera. The western flank is composed of deep-water turbidites in the San Jacinto foldbelt (Molina, 1986) and the eastern flank is composed of deltaic and coastal environments widely distributed a nd reaching the Llanos foothills (Villamil, 1999). Facies derived from the west belong to the Li sama Formation in the Middle Magdalena Valley and Guadala and Seca Formations in the Up per Magadalena Valle y (Villamil, 1990). Similar units of this age, but derived from the east, are the Molino and Barco Formations that are the scope of this study. Litostratigraphy and Depositional Environment Samples from Diablito are distributed along 1313.4 feet of core. The section comprises the Molino Formation, the Barco Formation, and the Cuervos Formation. A general stratigraphic column with the location of the samples is shown in Figure 3-1.

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29 Molino Formation The Molino (Catatumbo) Formation was named by Notestein et al (1944) from the Catatumbo Creek, in the department of Norte de Santander (Colombia). However, the outcrops in the river are not well preserved and the type section was transferred to a section obtained from the well “Oro numero 3” in the field Rio de Oro (Venezuela). The Molino Formation is composed of shales, often carbonaceous, with some ferruginous nodules and sporadically intercalation of fine sandstones. Thickness ranges from 300 to 600 feet. According Van der Hammen (1954, 1958) and Hubach (1957), the lower part of the formation is Maastrichtian in age. The Molino Formation in Diablito is at least 755 feet thickness, from the base of the recovered core (2300’) to 1545’ (Figure 3-1) and is mainly composed of biomicrites, finegrained glauconitic sandstones and sublitharenites. Barco Formation The Barco Formation was named by Notestein et al. (1944) from the anticline de Petrolea located in Sierra Barco del Este. The formation is composed mainly of sandstones, lutites and claystones. In the upper part of the section it is common to find one or two coal beds. The finegrain sediments (lutites and claystones) form a third part of the total thickness of the formation. Thickness ranges from 500 to 900 feet. The contact with the underlying Molino Formation is apparently concordant. The upper c ontact is normal and is marked by the appearance of the first important sandstone of the Cuervos Formati on. Van der Hammen (1958) dated the Barco Formation as early Paleocene based on pollen. In Diablito, the contact between the Molino Formation and the overlying Barco Formation is irregular. The formation is 1000 feet thickness and is composed of sideritic mudstones, fine-grained litharenites with calcareous cement, and sporadic coal beds in the lower part of the formation (Figure 3-1)

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30 A detailed sedimentological description and depositional environmen t interpretation of the KT boundary interval was done by German Bayona (written communication, 2006). The interval extends from 1755’ to 1540’ (Figure 3-2). Below 1645’ the sequence is characterized by a coarsening-upward sequence in which the dominant lithology is dark mudstones with s cattered fine sandstone beds. The thickness of the sandstone beds does not exceed 5 feet. Few small coal beds, < 1 feet thick, are present. Bioturbation is common as well as plant remains. The depositional environment for this sequence is interpreted by Bayona (pers. communi cation) as a prodelta to delta front (Figure 3.2). Above 1645’, the sequence is characterized by a fining-upward sequence and is mainly dominated by light-color siltstones with plane parallel lamination, scattered thin sandstone beds and small coal beds. This lithology suggests fine-g rained bay fill and channel fill successions in a delta front and delta plain. (Figure 3-2).

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31 Figure 3-1. General stratigraphic column of Diablito. Numbers on the palynological sample correspond to sample identification number and reflect the stratigraphic position of the sample

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32 Figure 3-2. Stratigraphic column of the interval where the KT boundary is located. Sedimentological description and depositi onal environmental interpretation done by German Bayona (written communication, 2006).

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33 CHAPTER 4 MATERIALS One rock core drilled by the DRUMMOND Coal Company in the Jagua de Ibirico (Cesar-Racheria basin, northern Colombia) (9 34’ N ,73 16’ W) was studied (Figure 4-1). The core (DIABLITO) is 2300 feet thickness and comprises, from older to younger, the Molino Formation (755 feet), the Barco Formation (966 feet), and the Cuervos Formation (579 feet). Samples were prepared at the Instituto Colombiano del Petroleo by the standard procedure of digesting the sediments in HCl and HF (Traverse, 1988) and then oxidizing. Thirty grams of sample were crushed and placed in a one-liter beaker. A 25% solution of HCl was added and left overnight to di ssolve carbonates. The HCl was decanted and the supernatant was discarded. The remaining muddy liquid was then centrifuged for 2 minutes at 1500 rpm and the supernatant was discarded. This step was repeated until the supernatant was completely clear. After the carbonate removal, the sample was transf erred to a copper beaker and placed in a fume hood. Then, 70% HF was added to the sample for ~ 24 hours. The sample was transferred to a polystyrene centrifuge tube and washed twice with water. The residue was transferred to a 50 ml glass centrifuge tube and 25% HCL was added. The residue was then centrifuged and decanted. The washing process was repeated until all by-pro ducts from the HF reaction were removed. To remove the fine organic material, 5 ml of Darvan # 4 solution was added to the residue and filled with water. A short centrifugation was done at 15 00-rpm for about 60 seconds. This process was repeated until the supernatant was clear. The residue was acidified with HCL for a better heavy liquid separation and the residual minerals were removed by decanting off the lighter organic fraction using a zinc bromide (ZnBr2) solution adjusted to a specific gravity of 2.0. Samples were allowed to sit for ten minutes before centrifuging for 15 minutes at 2000 rpm. Schultz solution was poured in to the tube with the residue and th e tube was placed in hot water for 4-12 minutes.

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34 The samples were washed several times (3-4) until the solution was neutral. A 10% NH4OH solution was added to the sample, which was placed in a hot water bath for 2 minutes. The sample was washed and centrifuged three times and sieved using a 7 m nitex screen cloth. Using a pipette, several cc of residue were siphoned and mixed with one drop of polyvinyl alcohol. The mix of residue and polyvinyl alcohol was distributed over the cover glass evenly and homogenously. When the polyvinyl was dry, a dr op of clear casting resin was placed on the slide near the center. The cover slip was turned and sealed. The slides were then dried for 24 hours. Two light microscopes were used for routin e palynologic analyses. A Carl Zeiss light microscope (Scope 2, # 4311267, Pa leobotany Laboratory, Florida Museum of Natural History) and a Nikon Eclipse 200 (Center for Tropical Paleoecology and Archaeology, Smithsonian Tropical Research Institute). For each palynolog ical slide, the oxidi zed and the non-oxidized residue was completely scanned with a 20x Ze iis planapochrormatic objective. At least 300 pollen/spores per sample were counted when poss ible. In a pollen count of 300 grains, taxa with >1% frequency are usually detected (Weng et al., 2006). When this number was reached, the remainder of the slide was scanned, without counting, to find new species. Examination and description of the palynological material was done using a 100x Zeiss oil inmersion planapochromatic objective. Identification of the palynomorphs found in this study, was done by comparison with photographs and descriptions of Cretaceous an d Paleocene material published for Northern South America (Van der Hammen, 1954a 1954b; 1956a; 1956b, 1966; Gonzales, 1967; Germeraad et al., 1968; Sole de Porta, 1971, 1972; Van der Kaars, 1983; Muller, 1987, Sarmiento, 1992; Sarmiento et al., 2000, Jaramil lo et al., 2001; Yepes, 2001, Jaramillo et al,

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35 2007) and comparison with the fossil pollen reference collection of the Smithsonian Tropical Research Institute and the Instituto Colombiano del Petroleo.

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36 Figure 4-1. Topographic map showing the location of Diablito (9 34’16 W, 73 16’ 45 N).

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37 CHAPTER 5 METHODS Diversity pattern through the KT boundary Ecological diversity can be measured in three different ways (Magurran, 1988): 1) counting the number of species, 2) by describing the relative abundances of species, 3) using one of several indices that combine information of these two components. In this study, several techniques were used to analyze the patterns of diversity. Richness and Rarefaction The number of species found in a study area is referred to as Richness (S) (Hayek and Buzas, 1997). This measure does not take into acc ount the number of individuals per species, or the way individuals are distributed among speci es. Richness is a function of the number of individuals counted and the probability of finding greater richness increases as the number of individuals counted increases (Magurran, 1988). Although 300 grains per sample were counted when possible, many of the samples did not reach this level, and the differences in richness between two samples can be due to differences in the number of counted grains and not to biological or ecological factors. Sander’s rarefaction, a sample reduction method (Hayek and Buzas, 1997), was used to estimate how many specie s might have been found within a sample if the sample had been smaller. In this way, th e richness between two samples with different size was be compared. Rarefaction values of 50, 75, 100, 150 and 200 specimens were used to test if the differences in richness were a consequence of different counts level. The unbiased version of the original Sandler’s formula was used (Hubert, 1971): = n N N N S Ei1 ) ( (5-1)

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38 Where, E(s) = Expected number of species. n = Standardized sample size. N = Total number of individuals. Ni = Number of individuals in each species Shannon-Wiever Index (H) Ecological diversity indices are the combina tion of the number of species (richness) and the distribution of individuals among these speci es (evenness). Several indices have been developed and basically they differ with respect to contribution of each of component to the index. The Shannon index (H) is the most common of the diversity indices. It is based on information theory and was derived indepe ndently by Shannon (Shannon, 1948) and Wiener. The index assumes that all the individuals come from a random sample of an infinite population and every species is represented in the sample (Magurran, 1988). H is calculated using: i ip p H ln = (5-2) where “ pi” is the proportion of individuals found in th e “i” species. However the real value of “pi” is unknown, it can be estimated as (ni / N), where “ni” is the number of individuals in the “i” species and “N” is the total number of individua ls (Magurran, 1983). H is equal to zero when there is only one species in the sample and a larger values of H occur when individuals within species are equally abundant. The value of H nor mally ranges between 1.5 and 3.5 (Magurran, 1988). The Shannon index was calculated for each sa mple to asses is there were differences between the Cretaceous and Paleocene samples. Range Through Method The Range-Through method (RTM) was used to estimate the standing diversity and the per capita extinction and origination rates. In the RTM, every species is considered present in all

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39 the samples between its first and last appe arance datum (Boltoskoy, 1988). This method smoothes the often spotty recovery of mic rofossil taxa and minimizes the effects of environmental influences (Hazel, 1970). The sing leton taxa (species represented by a single specimen) were eliminated from the analysis b ecause empirical and cla dogenetic models have shown that diversity measurements are best estimated if singletons are excluded (Sepkoski, 1990). Standing Diversity The Standing Diversity (SD) is an estimate of the taxonomic diversity of the group at the midpoint of a time interval (Harper, 1975), and it does not depend on the interval length (Foote, 2000). Each species occurrence known or inferred from the RTM was classified into one of the four fundamental classes of taxa de scribed by Foote (2000) (Figure 5-1). 1) FL : taxa confined to the interval with firs t appearance datum (FAD) and last appearance datum (LAD) both within the interval. 2) bL : taxa that cross the bottom boundary a nd have their LAD during the interval. 3) Ft : taxa that have their FAD during the interval and cross the top boundary. 4) bt : taxa that range through all the interval and cross both the bottom and top boundary. The SD was calculated for each sample using the proportional difference between the number of taxa crossing into an interval (botto m boundary crossers (Nb)) and the number of taxa crossing out of an interval (top boundary crossers (Nt)) (Foote, 2000) (See table 5.1 for equations). Edge Effect and Piecewise analysis The standing diversity calculated for each sa mple is based on the range through method; however when the interval falls toward either edge of the section the ability to infer the presence of the taxon by the range through method diminishes, creating an edge effect at both extremes of

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40 the section (Foote, 2002). The edge effect artific ially increases the number of first appearances and last appearances at the oldest and youngest pa rt of the section, respectively, creating an apparently abrupt decline in the standing diversity (Foote, 2006). To estimate the edge effect, a piecewise re gression analysis was done. The procedure assumes that two different regression functions fi t the same data and try a two-segment fit. The intersection of the two fitted regression lines is the breakpoint. The breakpoint is changed to all the possible positions and by iteration the position of the breakpoint that produces the regression with the lowest residual sum of squares is chosen (Yeager et al., 1989). The model follows the algorithm described in Duggleby and Ward (1991), modified by Jaramillo et al. (2006) for a twosegment linear regression: y= yt + [(mL + mR)(x-xT) [(mL + mR) x-xt ]/2 (5.3) Where, y = FAD or LAD x = species xt = breakpoint species yt = breakpoint FAD or LAD mL = slope left of breakpoint mR = slope right of the breakpoint A piecewise analysis was performed at the base and top of the standing diversity curve to eliminate the border effect. Graphic Correlation and Taxonomic rates Taxonomic rates refer to the rate at which new species originate and existing species become extinct (Foote, 2006). The per-capita origination ( p ) and extinction ( q ) rate is a measurement of the number of originations and ex tinctions scaled to the number of species at risk and to the time that they are at risk (Foote, 2006). Because p and q decline as interval length

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41 increases (Foote, 1994) it is necessary to subdivide the section in equal time intervals. The age of two levels in Diablito were roughly estimated usi ng the age of two key biostratigraphic events compiled from Jaramillo & Rueda (2004). These events were projected into Diablito using graphic correlation. This is a deterministic biostratigraphic technique (Copper, 2001) where a two-axis graph is used to express time equiva lence between two stratigraphic sections (Shaw, 1964). The events (FAD and LAD) that occur in bot h sections are plotted as points and if they are synchronous and the sedimentation rate is equa l, the points would plot on a straight line with slope equal to one (Hammer and Harper, 2006) However, because the fossil record is incomplete and the sedimentation rate is usually unequal, the observed order of events in two sections is normally different, producing a cloud of points in the scatter plot. The objective of graphic correlation is to fit the points to a straight line or segments of line and the best solution is the line of correlation (LOC) that causes the minimum disruption of the best-established ranges (Edwards, 1995). Establishing the LOC is the most problematic part of the graphic correlation (Edwards, 1995). Although sophisticated techni ques can be used to trace the LOC (e.g. Constrained optimization (Sadler, 2003); Gene tic Algorithms (Zhang, 2000)), with a good biostratigraphic and geological knowledge of th e sections the LOC can be traced manually (Hammer and Harper, 2006). Once the LOC is traced, the range of taxa in one section can be projected onto the most complete section to pr oduce a composite section. This procedure is repeated with all the available sections until a stable composite section is obtained (Zhang, 2000). Diablito was plotted against one section that spans the KT boundary in Rio Loro, Venezuela. The biostratigraphic information for this section was taken from Jaramillo et al (2006) and Yepes (2001). The line of correlation was traced manually and the ages of two key

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42 biostratigraphic events were projected on Diablito These data were used to calculate a rough sedimentation rate through the section and with this information it was possible to divide the section into one million time intervals. Taxonomic rates (p and q) were then calcula ted using the number of taxa that range completely through each interval (both boundary cro ssers (bt)) relative to the total number that cross into or out of the interval (bottom or top boundary crossers (bL, Ft)) (Foote, 2000) (See Table 5-1 for equations). Cluster Analysis Cluster analysis is an exploration and visuali zation technique that allows one to separate groups of samples with similar composition from other samples. Such groups are searched on the basis of similarities in measured or counted data between sample s. This analysis is sometimes preceded by transformation (eg. logarithmic tran sform, conversion of numerical abundances to presence/absence values) and standardization (s tandardization to total, standardization to maximum and z transform) that make the data more amenable for statistical analysis and weight samples so that they contribute to the statistical analysis more equally (Olszewski, pers. communication). To assess the similarity between sa mples, a distance-similarity measure is used and a clustering algorithm that defines the distance between the clusters (Hammer and Harper, 2006) is chosen. Classical clustering in paleo ecology and biology has used the agglomerativehierarchical approach. In this algorithm, every clustering step is governed by the recalculation of similarity coefficients between established clusters and the possible candidates, and an admission criterion for a new member (Sneath & Sokal, 1973). Possible changes in the palynological compos ition between the Cretaceous and Paleocene samples were tested using an agglomerative-hierarchical cluster analysis. A presence-absence transformation was used to run the analysis a nd range through was assumed. Euclidean distance

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43 (root sum of squares of the differences) and Manha ttan distance (sum of the absolute differences) were used as metrics to calculate the dissimilarity between the samples and several clustering methods (average, single, complete ward and weighted) were tested and their results compared to achieve the best results. Extinction percentages To calculate the palynological extinction per centage in Diablito, a Chi-square analysis was used. The procedure is similar to that used by Hotton (2003) in a KT boundary section located in Central Montana (U.S.A).This statistic compares the entire set of observed counts with the set of expected counts (Moore and McCabe, 2003). Chi square takes the difference between each observed and expected count and squares these values so that they are all zero or positive. To standardize, each squared difference is divided by the expected count. = ected ected observed X exp ) exp (2 2 (5-4) For each species in Diablito, the number of Cretaceous and Paleocene samples where a species was found is the observed count for each category (Cretaceous vs. Paleocene). The expected count is the number of samples where th e species would be expected to be found if the null hypothesis is true. The Chi square valu e for each species was calculated using : P P P K K Kected ected observed ected ected observed X exp ) exp ( exp ) exp (2 2 2 + = (5-5) Where k is Cretaceous and p is Paleocene. The first step in the analysis was character izing the distribution of palynomorph species above and below the KT boundary. Species were classified as belonging to one of three categories. Those species occurring either ex clusively below the KT boundary or undergoing

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44 highly significant (p<0.04) reduction above the KT boundary were termed K species. Species displaying no significant change in presence across the boundary were termed KT species. Those species undergoing significant increase in the Paleocene were termed P species. The extinction levels were estimated using the percentage of species in the K category with respect to the KT and K categories. All analysis was done using R for Statistical Computing (The R project for Statistical Computing, www.r-project.org)

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45 Figure 5-1. Four fundamental classes of taxa present in each stratigraphic interval. FL : species confined to the interval, bL : species that cross only the bottom boundary, Ft : species that cross the top boundary only, bt : species that cross both boundaries. (Modified from Foote, 2000). Table 5-1. Equations to calculate mean sta nding diversity and per capita extinction (q) and origination (p) rate for intervals of length t. Measurements are expressed in terms of numbers belonging to the four fundamental classes of taxa (see Figure 2) (modified from Foote, 2000) Measure Definition Mean Standing Diversity (Nb + Nt ) / 2 Per capita Origination rate, p -ln (Nbt / Nt ) / t Per capita Extinction rate, q -ln (Nbt / Nb ) / t Bottom-boundary crossers, Nb NbL + Nbt Top-boundary crossers, Nt NFt + Nbt

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46 CHAPTER 6 RESULTS The palynological content of 82 samples spa nning the Diablito rock core was studied. Three hundred and seventy morphospecies, including pollen, spores and dinocysts, were identified. The individual occurrence of 17.890 palynomorphs was recorded. Twenty-five species of dinocysts were found of which seven were not identified to the species level and simply regarded as sp. One hundred and twelve morphospecies of spores were found and nearly 70% are new, unnamed morphospecies. Of the 232 species of pollen, at least 55% are new morphospecies that have not been formally de scribed in the literature. Some of them were unnamed and some were regarded as sp. The unna med species are indicated by quotation marks. The species are not considered formally described because a dissertation is not considered a valid publication (Traverse, 1996) and formal description was beyond the scope of this study. Formal description of the morphospecies is found in the literature (Van der Hammen, 1954a, 1954b, 1956a, 1956b, 1966; Van der Hammen & Wymstra, 1964; Gonzales, 1967; Germeraad et al., 1968; Sole de Porta, 1971, 1972; Van der K aars, 1983; Muller, 1987; Sarmiento, 1991; Sarmiento et al, 2000; Jaramillo et al, 2001, 2007; Yepes, 2001) and photographs of some representative species encountered in this study are found in Appendix B. The list of morphospecies, their first appearance datum (F AD), last appearance datum (LAD) and number of samples in which they were found are listed in the Appendix A. Detecting the KT boundary To asses changes in diversity and palynologi cal extinction percentages in Diablito, it was necessary to first determine the position of the Cretaceous Tertiary boundary (KT boundary). The first line of evidence used to detect the KT boundary in Diablito was the disappearance of typical Cretaceous palynomorphs. The level where th ese species have their LAD is considered a

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47 good approximation of the position of KT boundary. According to previous studies (Germeerad et al., 1968; Muller et al., 1983; Sarmiento, 1992) sp ecies restricted to Cretaceous sediments in northern South America are: Buttinia andreevi Echimonocolpites protofranciscoi and Proteacidites dehaani Their stratigraphic distribution and abundance is shown in Figure 6-1. The LAD of Echimonocolpites protofranciscoi Buttinia andreevi and Proteacidites dehaani are 1635.7’, 1638.2’ and 1672.8’, respectively, placing the KT boundary between 1599.5’ and 1638.2’. In their last record, only one or two individuals were recorded. Cluster analysis shows that the palynological composition of samples 1635.7’, 1638.2’ and 1599.5’ is more related with the upper part of the section (Figure 6-16), suggesting that the last record of these three species could be indicating reworking. The sample with the last important record of Echimonocolpites protofranciscoi (recording the disappearance of more than 2 individuals) is at 1647.4’. This species is especially important because its stratigraphic range has been used in northern South America as a good indi cator of the late Cretaceous and its LAD has been used to identify the Mesozoic-Cenozoic boundary (Jaramillo, 2006). To identify the stratigraphic level in Diablito with the highest number of LADs, a histogram of the number of LADs throughout the section was constructed (Figure 6-2). By far the interval with the highest number of LADs (119 palynomorphs) is between 1600’ and 1800’. A plot of all the species with LADs in this in terval (Figure 6-3) shows a stepwise pattern of disappearances resembling a gradual extinction scenario. However, this is a sampling artifact related to the fact that most species composing a community are rare species and are only recorded in a few samples. The histogram of the number of samples in which each species was recorded between the base of Dialito and 1600 ’ (Figure 6-4) shows that 104 species were recorded in only 1 to 5 samples and only 15 samples were recorded in >5 samples. The

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48 probability of finding rare species in the samples immediately below the extinction layer is very low. This so called Signor-Lipps effect (Signor & Lipps, 1982) predicts that the distribution of last appearances of a group of species appears gr adual, even if all the species became extinct simultaneously. This pattern also makes it difficult to precisely pinpoint the stratigraphic position of the KT boundary that is usually represented by very thin stratigraphic horizons. The palynological record in Di ablito indicates a dramatic change in diversity around 1640’-1650’ (Figure 6.14). The change is coincide nt with the significant extinction of typical Cretaceous species (Figure 6.3) and the cluster an alysis (Figure 6.16) shows two very different palynofloras. All samples below 1640’ form one cluster and all the samples above 1640’ form the second cluster. Evidences suggests that im portant changes in the palynoflora occurred between 1640 and 1650’. To identify the position of the KT boundary more precisely and compare the biological evidence with an independent line of sedimentary evidence, a magnetic susceptibility analysis was performed between 1620’ and 1680’. Magnetic Susceptibility (MS) When an external magnetic field is applied to a rock sample, some of the mineral grains acquire an induced magnetization. MS is an indi cator of the strength of this induced magnetism within the sample and is largely function of the concentration and composition of the magnetizable material in the sa mple (Evans & Heller, 2003). MS in stratigraphic profiles has been related to the combination of two signals (Ellwood, 2001), a high-frequenc y and low amplitude signal associated with climate-driven cyclic changes in weathering and erosion, and an irregular and lowfrequency signal that is dominated by eustasy (Ellwood et al., 2003). When sea level rises, base level falls and erosion increa ses, thus more detrital grains are brought to the sediments, producing MS highs. The low frequency component of the MS signal can be used for global correlations because the mechanism that controls the signal is eustasy. Ellwood et al.

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49 (2003) used MS data from five KT boundary sections around the world (Figure 6.5) to establish a reference MS signature of the boundary that allowed narrowing the search for the impact evidence in new sections. The KT boundary sequence in all five sections starts from a clear decrease in the MS signature below the boundary, wh ich is interpreted to represent a global sea level rise in the latest Cretaceous (gray circle in Figure 6.5). Above the event layer produced by the impact, there is a major increase in the MS signature representing a rapid, but short period of enhanced continental erosion (Ellwood et al., 2003). This very distinctive and consistent pattern found in other KT boundary sections was used to narrow the interval where the KT boundary lies in Diablito. Magnetic susceptibility was measured in 200 samples spaced evenly through the 60-foot interval where, according to th e palynological evidence, the KT boundary is presumably located (Figure 6.6). Approximately 30 grams of sediment were used for each sample. MS was measured with a KLY-3 Kappabridge (Agico, Inc) by Victor Villasante (Laboratorio de Paleomagnetismo, Universidad Complutense de Madrid). Due to the probability of obtaining low MS values in certain lithologies (Evans & Heller, 2003), each sample was measured ten times and the average was calculated. Results are shown in Figure 6.6. The MS signature in Diablito is stable thr ough the whole section with a slight decreasing trend from the base to the top (Fig 6.7) and some sporadic increases in the MS restricted to some samples (1608.15’, 1622.95’, 1636.07’, 1641.32’, 1653.789’) (Figure 6.6). According to the paleoenvironmental interpretation, samples with high MS values are restricted to the mouth barprogradation and the delta front, however they come from different lithologies (Table. 6.1), indicating that high values in MS are not related to a particular lithology.

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50 The MS signature in Diablito decreases abruptly at 1647.5’ (Fig. 6.6). This pattern resembles those found by Ellwood in several sections of the boundary (Fig.6.5) and has been explained as the result of a global sea level rise in the latest Cretaceous prior to the KT boundary crisis. Above this level, Ellwood et al. (2003) found evidence, including an Iridium anomaly, a negative shift in 13C, microspherules and enrichment of rare elements that have been related with the KT event. The MS pattern seen in Di ablito indicates that the KT boundary probably lies at a depth between 1640’ and 1650’. In conclusion, several pieces of evidence suppor t placing the KT boundary in Diablito at a depth between 1640’ and 1650’: • Extinction of typical Cretaceous species (Figure 6.1). • High number of LADs recorded between 1600’ and 1800’ (Figure 6.2). • A dramatic change in diversity recorded at 1640-1660’ (Figure 6.14) • Cluster analysis, showing two different associations separated at 1640’-1650’. • The abrupt negative shift and subsequent p eak at 1645’-1647’ in magnetic susceptibility, resembling the pattern found in other KT boundary sections. (Figure 6.6). Additional analyses are being used to better identify the KT boundary event, including iridium concentrations, petrography and stable isotopes. The aim of these analyses is to detect the iridium anomaly that has been linked w ith the boundary, find micro spherules and shocked quartz related with the impact and to detect the negative C13 anomaly, that have been detected in other sections of the boundary. Diversity pattern through the KT boundary A diversity analysis of the pollen and spores record in Diablito was performed to know if the event at the KT boundary had a subs tantial effect on the vegetation

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51 Richness and Rarefaction The richness (S) (number of species), was calculated for each sample (Fig. 6.8) The mean richness of morphospecies for the Cretaceous samples is 28.8 and the mean number of morphospecies for the Paleocene samples is 17.5. To test if there is a difference in the mean ( ) number of species between the Cretaceous (c) and the Paleocene (t) a t-test was done. (Ha: c > t vs. Ho: c t). The t-test requires that the two popul ations from which samples were drawn have a normal distribution and equal variances. To assess the normality of the two data sets, a normal probability plot (QQ plot) for each populati on was constructed, a nd to test for equal variances (H0: 2 c = 2 t vs Ha: 2 c 2 t, where c: Cretaceous and t: Paleocene) an F test was done The QQ plot (Fig. 6.9) shows that the distribution of richness values for the Cretaceous and the Paleocene are roughly normally distribut ed. The F test, using an error type I ( : 0.01), indicated no significant difference between the vari ances with a p: 0.78 (F=1.09, df= 37). The result of the t-test, using an error type I ( : 0.01), suggests that the mean richness of the Cretaceous is significantly higher that the mean richness of the Paleocene with a p = 0.00002 (t: 5.26 and df: 76.8). Although 300 palynomorphs were counted when was possible, some samples did not reach this level and the differences in richness can be due to the fact that the richness increases with the sample size (Magurran, 1988) and not to ecological factors. For example, in the Cretaceous the mean of counts was 249 grains, howe ver, the sample with the lowest count was 53 grains, and there were two more samples with counts < 100 grains (82 and 65). In the Paleocene, the mean number of grains counted wa s 191, the sample with the lowest count had 15 grains and there are 14 more samples with counts < 100. To determine if differences in the counts explain the difference in richness, a raref action at 100 grains was done. Samples with <

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52 100 grains were excluded from the analysis (Fig. 6.10). The mean richness of the Cretaceous is still significantly higher than the richness of the Paleocene samples after the rarefaction, p < 0.001 (Cretaceous mean richness : 21 spp.; Paleocen e mean richness: 15 spp.) (t = 4.23, df = 63). The two conditions for the t-test, normal distri bution of the two population and equal variances were tested again for the reduced dataset and verified. Shannon Index Diversity indices characterize the diversity in terms of richness and evenness of a sample or community using a single number (Magurra n, 1988). The Shannon index (H) was calculated for each sample through the section (Fig 6.11). A ttest was performed to determine if the mean Cretaceous H ( =2.23) is higher that the mean Paleocene H ( =1.79). The F test, using an error type I ( : 0.01), indicated no significant difference betw een the variances with a p=0.37 (F=0.75, df= 43), however the QQ plot of the two populations (Fig. 6.12) show that normality cannot be assumed. In the case of the Paleocene, the extreme value of H (0.29) obtained for the sample 1438’ is an outlier that produces a distribution skewed lower values (Fig. 6.13) and in the case of the Cretaceous, three samples with low values of H also produce a distribution that is skewed to the lower values (1744’= 0.87; 1732.1= 1.0; 1706 = 1.29). For this reason the nonparametric Wilcoxon Rank sum test (also known as Mann-Whitn ey) was used to test the hypothesis of higher values of H in the Cretaceous. In this test the extreme values do not have a strong effect on the statistic, and it only require s equal variance, but does not require that the populations have a normal distribution (Ott & Longnecker, 2004). According to the test, the evidence suggests that the H of the Cretaceous is higher than the H for the Paleocene (W= 1292; p< 0.005).

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53 Standing Diversity The standing diversity, assuming range through me thod, was calculated for each sample (Fig. 6.14). The singletons (species occurring only in one sample) were rem oved and only pollen and spores were used in the analysis The abrupt increase and decline in standing dive rsity at the beginning and end of the section, respectively, is a product of the edge effect, wh ich artificially increases the number of FADs and LADs (Foote, 2006). To estimate this effect and obta in a more realistic pattern of the diversity, a piecewise analysis was applied to the standing diversity data. The edge effect at the oldest part of the section was estimated using the standing di versity values between the samples 2097.1’ and 1696.3’, and according to the analysis, the breakpoint is at 1885’. For the youngest part, the standing diversity between the samples 794.7’ and 1696.3’ was used, and the breakpoint was found at 988.8’. Finally, the samples between 1885.2’ and 2097’ and 794.7’ and 988.8’ were removed from the standing diversity curve (Fig 6.15). Changes in Composition Changes in the palynolofloral composition throughout the boundary were assessed using an agglomerative cluster analysis. The function Agnes from the package CLUSTER was used (R project for Statistical Computing). The numerical abundances were converted to presence-absence values and the range through method was assumed. Two distances were used (Manhattan and Euclidean) and three linking algorithms were tested (ward, single, average). The best result was obtained using Euclidean distance and the average linking algor ithm (unweighted pair-group average method, UPGMA)(Fig 6.16). The agglomerative coeffi cient (Kaufman & Rousseeuw, 1990), that measures the clustering structure of the dataset, was 0.74.

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54 Taxonomic Rates Graphic correlation was used to compare Diablito with one section that spans the KT boundary located in Rio Loro, Venezuela The bi ostratigraphic information of the Rio Loro section was taken from Jaramillo et al. (2006) and Yepes (2001). Thirty-six palynomorphs (pollen, spores and dinocysts) were used in th e graphic correlation and selected based in their common occurrence in both sections and their potential as biostratigraphic markers. The FAD and LAD of the taxa are summarized in Table 6.2 To roughly divide Diablito into equal time inte rvals, two biostratigraphic events compiled from Jaramillo et al. (2006), were projected from Rio Loro to Diablito. The two key stratigraphic datum’s are: 1. LAD of Echimonocolpites protofrancscoi has been used as the Mezosoic-Cenozoic boundary (65.50 0.3 My, (Grandstein et al., 2004)). The depth of this event in the Rio Loro section is 943 m. 2. The base of the Bombacacidites annae zone according to Jaramillo et al. (2006), corresponds to the carbon isotope shift of the early to late Paleocene (60.00 0.2 my). The FAD of Bombacacidites annae among others, characterizes the base of this zone (Jaramillo & Rueda, 2004). The depth of this event in the Rio Loro section is 1081 m. The line of correlation (Fig 6.17) was traced manually giving more importance to taxa with known high biostratigraphic value (e.g Echimonocolpites protofranciscoi Foveotricolpites perforatus Syndemicolpites typicus Proteacidites dehaani Buttinia andrevii ). The equation for the line of correlation is: X= -4.92Y + 5704 (6-1) Using equation 6-1, the projected LAD of Echimonocolpites protofranciscoi in Diablito is 1653.27’ and the projected LAD of Bombacacidites annae is 1060’ (Fig 6.17). A rough estimate of the sedimentation rate in the Diablito core was calculated using the slope of the line of correlation. The Y-axis was replaced for the time (My) of events.

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55 Slope (m) = X2 –X1 / Y2 – Y1 ; m = 1653.27 ‘ – 1060 ‘ / 65.5 My – 60.0 My m = 108’ / My The age for each sample was estimated using the equation of the line (6-2) that relates the depth of the two events ( Echimonocolpites protofranciscoi (1653.27’) and Bombacacidites annae (1060’)) and proposed age for these events (65.5 My and 60.0 My respectively). Y (My)= 0.009275 x Depth (feet) + 50.16 (6-2) With the assigned age for each sample, Diablito was then divided in 1 million time intervals and the number of species in each bin belonging to one of the four categories of Foote’s taxa (2002) was calculated (Table. 6.3). The per-capita origination ( p ) and extinction ( q ) rates (Foote, 2002) were calculate as: p = -ln (Nbt / Nt) / t (6-3) q = ln (Nbt / Nb) / (6-4) The results of p and q are shown in Figures 6.18 and 6.19, respectively. Extinction percentages The palynological analysis of Diablito show s that an important proportion of species recorded in the Cretaceous disappear at the proposed KT boundary (1640’-1650’) or some feet below the boundary (Fig. 6.20). Previous studies al so have shown that characteristic Cretaceous palynomorphs of northern South America have th eir last appearance close to end of the Cretaceous (Sarmiento, 1992). The extinction of palynomorphs in the Diablito was estimated as the number of palynomorphs (pollen and spores) seen in the Cretaceous that disappear below the proposed KT boundary in relation to the number of palynomorphs that are seen in the Cretaceous as well in the Paleocene. Using a chi square analysis, each species of pollen and spores found in Diablito was

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56 classified as belonging to one of three categories: 1) K species : species found only below the boundary or undergoing highly significant reduction in presence above the KT boundary 2) KT species : species displaying no significant change in presence across the boundary and 3) P species : species only found in the Paleocene or undergoing significant increase in presence in the Paleocene. A similar procedure was used by Hott on (2002) in one section of the KT boundary located in Central Montana, U.S.A. According to this analysis, and if all the species of pollen and spores are used, including singletons (species that were only recorded in one sample), the number of species in the K category is 172, the number of species in the KT category is 77 and the number of species in the P category is 96 (Fig. 6.21). Of the total number of species of the KT and P categories (249 spp) at least 69% (172) disappear below or at the proposed KT boundary. This percentage was taken as the extinction level. If the singletons are removed from the analysis, the number of species in the K category is reduced to 72 spp, the number of species in the KT category remains constant and the number of species in the P category is reduced to 44 spp (Fig. 6.22). The percentage of extinct species is 48%.

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57 Figure 6-1. Stratigraphic distribution and abunda nce of Echimonocolpites protofranciscoi, Buttinia andreevi and Proteacidites dehaani. E. protofranciscoi (LAD): 1635.7’;B. andreevi (LAD): 1638.2’; P. dehaani (LAD): 1599.5’. Figure 6-2. Histogram of the number of LADs. The highest concentrations occurs at a depth between 1600’ and 1800’

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58 Figure 6-3. Graphic showing LAD and FAD of species that disappear between 1600’ and 1800’. The pattern of extinction is gradual because of the Signor-Lipps effect (see text for explanation). Figure 6-4. Histogram of the number of samp les where the species with LAD between 1600’ and 1800’ were recorded.

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59 Figure 6-5 Magnetic susceptibility pattern found in five different sections of the KT boundary. All curves show a decrease in the MS signature before the boundary (gray circle) and a sharp increase across the KT boundary (arrow). Modified from Ellwood et al., 2003.

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60 Figure 6-6. Magnetic susceptibility (MS) pattern th rough the interval where the abrupt change in palynological diversity and extinction of typical Cretaceous species is detected (1600’-1700’). A negative shift in the MS signature is observed at 1647.5’ with a subsequent peak in MS at 1641.32’

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61 Figure 6-7 Magnetic susceptibility of the KT boundary interval in Diablito. A slight decrease in the MS is seen from 1600’ to 1700’ in the section (black line). Figure 6-8. Number of species (S) vs. Depth in Diablito. The KT boundary lies at approximately 1640 feet (horizontal black line).

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62 Figure 6-9. Normal QQ plot of the mean num ber of species (S) in the Cretaceous and the Paleocene. (TQ: theoretical quantiles, SQ: Samples quantiles) The condition of normality can be assumed

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63 Figure 6-10. Rarified richness at 100 grains. The mean richness for the Cretaceous is significantly higher than for the Paleocene (t-test: p <0.01). The KT boundary lies at ~1640 feet.

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64 Figure 6-11. Shannon index (H). The KT boundary lies at ~1640 feet (horizontal black line).

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65 Figure 6-12. Normal QQ plot of the mean Shannon index (H) of the Cretaceous and the Paleocene. (TQ: theoretical quantiles, SQ: Samples quantiles) The condition of normality can not be assumed.

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66 Figure 6-13 Boxplot of the Shannon index for the Cretaceous and the Paleocene. Cretaceous Paleocene

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67 Figure 6.14 Standing diversity using range-through method. Singletons were not used in the analysis. Note the abrupt increase and the decrease of the standing diversity produced by the edge effect. The KT bounda ry lies at 1640 feet (horizontal black line).

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68 Figure 6-15 Standing diversity using range-through method. Singletons were not used in the analysis. The edge effect was removed from the curve. The KT boundary lies at 1640 feet (horizontal black line).

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69 Figure 6-16. General stratigraphic column of Diablito showing lithology and Cluster analysis of the samples using Euclidean distance and the average method. The data were transformed to presence-absence and range through was assumed. The KT boundary lies at 1640’.

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70 Figure 6-17. Graphic correlation. Diablito vs. Rio Loro. See table 2 for the name and datum for each taxon. The line of correlation wa s traced manually (X=-4.92+5704). Two biostratigraphic events, Echimonocolpites protofranciscoi (LAD) and Bombacacidites annae (FAD), were projected from Rio loro to Diablito to divide the section in equal time intervals.

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71 Figure 6-18. Per capita origination rate calculate d using the per capita rates of Foote (2002). The origination rate per million years is stable through the section, however higher values are seen in the Cretaceous and the lower part of the Paleocene. The edge effect was removed from the data. The KT boundary lies at 1640’ (black line) Figure 6-19. Per capita extinction rate calculated using the per capita rates of Foote (2002). The extinction rate per million years shows low a nd stable values in the Cretaceous with an abrupt increase at the KT boundary. After the KT boundary (black line) the extinction rate shows low and stable values.

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72 Figure 6-20. Presence-absence distribution char t of pollen and spores recorded in Diablito. Note the high number of last occurrences at the proposed KT boundary (black horizontal line) and below the boundary Figure 6-21. Number of species in each of the K, KT and P categories. All the species of pollen and spores, including singletons, were used in the analysis. The extinction level was calculated using the percentage of the num ber of species in the K category with respect to the number of species in the KT and K categories (species recorded in the Cretaceous and the Paleocene). The extinction level is 69%. K category: species occurring either below the KT boundary or undergoing significant reduction in presence above the KT boundary; KT category : species displaying no significant change across the KT boundary and P category: species that were recorded only in the Paleocene.

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73 Figure 6-22. Number of species in each of the K, KT and P categories. The singletons were excluding for the analysis. The extinction leve l was calculated using the percentage of the number of species in the K category with respect to the number of species in the KT and K categories (species recorded in the Cretaceous and the Paleocene). The extinction level is 48%. K category: species occurring either below the KT boundary or undergoing significant reduction in presence above the KT boundary; KT category : species displaying no significant change across the KT boundary and P category: species that were recorded only in the Paleocene. Table 6-1. Lithology of samples with high magnetic susceptibility values. High values are not restricted to a particular lithology. Sample Lithology 1608.15 Mudstone-Siltstone light color 1622.952 Mudstone-Siltstone light color 1636.072 Sandstone 1653.789 Mudstone-Siltstone dark color 1641.32 Mudstone-Siltstone dark color

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74 Table 6-2. First (FAD) and Last (LAD) appearance datums for 71 taxa used in the graphic correlation. Biostratigraphic information of Rio Loro was taken from Jaramillo et al. (2006) and Yepes (2001). Diablito (feet) Rio Loro (m) code taxa FAD LAD FAD LAD 1 Andalusiella mauthei 1517.5 891 2 Annutriporites iversenii 1965.5 833.45 3 Ariadnaesporites sp. 1633.8 849 4 Bacumorphomonocolpites tausae 2018 976.6 5 Bombacacidites annae 794.7 1081 6 Buttinia andreevi 1638.2 900.1 7 Cerodinium diebelii 2018 910.5 8 Cerodinium pannuceum 1941.4 915 9 Cordosphaeridium sp. 1885.2 879.5 10 Corsinipollenites psilatus 1885.2 900.1 11 Crusafontites grandiosus 1849.4 900.1 12 Duplotriporites ariani 1885.2 910.5 13 Echimonocolpites protofranciscoi 1635.7 943 14 Foveotricolpites perforatus 931 1115.5 15 Gabonisporites vigourouxii 1648.1 936 16 Gemmamonocolpites dispersus 1672.8 953 17 Longapertites microfoveolatus 794.7 1157 18 Longapertites van eendenburgii 931 1185 19 Mauritiidites franciscoi var. franciscoi 1179.6 1022 20 Monocolpites grandispiniger 1797.9 910.5 21 Palaeocystodinium sp. 1885.2 943 22 Periretisyncolpites giganteus 1638.2 989 23 Proteacidites dehaani 1599.5 936 24 Proxapertites tertiaria 931 1188.5 25 Racemonocolpites racematus 1356.8 976.6 26 Retidiporites magdalenensis 794.7 1179 27 Senegalinium sp. 1672.8 922 28 Spinizonocolpites baculatus 1638.2 976.6 29 Spinizonocolpites echinatus 1751.7 871 30 Stephanocolpites costatus 1490.6 976.6 31 Syndemicolpites tipicus 1641.3 936 32 Tetradites umirensis 1641.3 922 33 Thalassiphora sp. 2097.1 910.5 34 Tricolpites aff. microreticulatus 1758.3 845 35 Trithyrodinium sp. 2062.9 915 36 Zlivisporis blanensis 1249.2 976.6

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75 Table 6-3. Number of species per bin in each one of the Foote’s taxa categories. The midpoint is the mid depth position between the lower and upper depth of the bin. X: number of taxa. bL: taxa that cross the bottom boundary and make their LAD during the interval; Ft: : taxa that ha ve their FAD during the interval and cross the top boundary; FL: taxa confined to the interval which FAD and LAD are both within the interval; bt: taxa that range through all the interval and cross both the bottom and top boundary; Nb : Bottom boundary crossers (NbL+Nbt); Nt : Top boundary crossers (NFt+Nbt) (See Fig.4). BIN Midpoint (Feet) XbL XFt XFL Xbt Nb Nt 1 812.65 38 0 5 0 38 0 2 904.1 26 3 14 35 61 38 3 1020.55 10 2 8 59 69 61 4 1109.85 1 0 2 69 70 69 5 1214.4 13 4 7 66 79 70 6 1332.7 10 6 5 73 83 79 7 1445.6 10 4 5 79 89 83 8 1553.1 17 10 13 79 96 89 9 1654.35 39 13 39 83 122 96 10 1757.75 12 18 31 104 116 122 11 1853.35 9 22 21 94 103 116 12 1979.7 2 38 21 65 67 103 13 2080 0 29 9 38 38 67 14 2244.4 0 38 10 0 0 38

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76 CHAPTER 7 DISCUSSION Several sections with continental records of the KT boundary have been studied in the northern hemisphere (U.S.A and Canada) showi ng dramatic changes in the vegetation as a consequence of the KT boundary event. The e ffect on tropical vegetation was totally unknown and not a single section had been reported from the tropics. In this work, I studied one section with a continental record of the KT boundary w ith the aim of detecting changes in diversity through the boundary and the extinction percentage associated with the KT boundary event. The section is a rock core (DIABLITO) drilled in the Cesar-Rancheria basin, northern South America, and is composed of 2200 feet of sandst ones, coal, and shales deposited in transitional environments during the Maastrichtian and Paleocene. In the western interior of North America, the KT boundary has been associated with the extinction of several palynomorphs and palynology ha s become one of the main tools to identify the boundary (Nichols and Johnson, 2008). The first line of evidence used in Diablito to detect the boundary, or at least to restrict the interval where the boundary is located, was the disappearance of species considered typically Cretaceous by some authors (Germeerad et al., 1969; Muller et al., 1983; Sarmiento, 1993; Jaramillo et al., 2006). The last appearance datum (LAD) of Echimonocolpites protofranciscoi Buttinia andrevii and Proteacidites dehanni show that the end of the Cretaceous in Diablito is located at a depth between 1638.2’ and 1672.8’. Additionally, the standing diversity curve (Fig. 6.14) shows an abrupt decrease in diversity between 1640’ and 1650’ and the cluster analysis depicts two very different palynological associations between 2244.4’ and 1641.3’ and between 1638.2’ and 794.7’ (Fig. 6.16). The histogram of the number of LADs (Fig. 6.2) al so shows a high concentration of disappearances in the interval where the other changes in the palynoflora are seen. The nature of these changes

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77 is discussed below, but is important to say that based on the palynological record, it was possible to narrow the KT boundary to an interval of approximately ~ 30 feet. Although a more detailed palynological study of this 30-foot interval w ould probably narrow even more the KT boundary interval, the nature of biological communities a nd the fossil record make the record of last appearances in a mass extinction scenario look gr adual, even if all the species became extinct simultaneously (Signor-Lipps effect). In extant and extinct communities, most of the species are represented by only a few individuals (rare species ) and most of the individuals that compose a community belong to only a few species (Magurran, 1983). The distribution of fossils is also controlled by lithofacies, sampling intensity and sample preservation (Nichols and Traverse, 1971). In this sense, the probability of finding individuals of rare species in samples below the extinction layer is very low a nd although an intense sampling near the layer could increase this probability, the product is only the smoothing of the Signor-Lipps effect. To identify the exact position of the KT boundary based only on the palynological record is difficult so to narrow the KT boundary inte rval in Diablito, magnetic susceptibility (MS) analyses were carried between 1600’ and 1700’. E llwood et al. (2003) used several sections to establish a reference magnetic susceptibility signature for the KT boundary. According to this study, below the boundary there is a sudden decrease in MS that represents a sea level rise in the latest Cretaceous, followed by a major increase in MS interpreted to represent a rapid, but short period of enhanced continental erosion (Ellwood et al., 2003) (Fig. 6.5). Between these two levels, Ellwood reported an iridiu m anomaly, a negative shift in 13 C and microspherules that allow precise location of the KT boundary and as sessment of the relation between the boundary and the MS signature.

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78 The negative shift in Diablito at 1647.5’ (Fig. 6.6) is very similar to those found by Ellwood et al. (2003) immediately below the KT boundary in different sections around the world. Above the negative shift, several MS peaks are found in Diablito. The peaks are independent of the lithology and facies and a lthough similar facies and lithology are find in the lower part of the section (below 1647.5’), only one peak is found below 1653.7’, suggesting that the high MS values are restricted to the upper part of the section. A detailed study of the mineralogical composition of the samples is necessary to test if the peaks in MS found in the upper part of the section can be explained by diffe rences in the concentration and/or composition (mineralogy and grain size or shape) of the ma gnetizable material in the samples above and below the negative shift. These factors are largely responsible for the MS signature in a rock sample (Ellwood et al., 2003). The first significant p eak above the MS negative shift is located at 1641.32’ in Diabltio. According with the interpretation of Ellwood et al (2003) this peak is located above the iridium anomaly, and other evidence of the KT boundary (shocked quartz, spherules, etc…), indicate that if the Ir anomaly is preserved in Diablito, it is probably located between 1641.32’ and 1647.5’. Finally, the sections studied by Ellwood et al. (2003) were deposited in deep oceanic environments. It has been suggested that the MS signature will not be useful in non marine sections, very proximal marine s ections, or sections that are severely diagenetically modified (Ellwood et al., 2003). The interval where MS was measured in Diablito (1600’-1700’) represents deltaic environments (Fig. 3.2), sugges ting that MS analysis probably can be used in sections representing more transitional environmen ts of deposition. It will be important to study the MS signature of sections with environmen ts of deposition similar to Diablito to corroborate

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79 the results found in this study. If the same pattern is found in other section, MS analysis can be used not only to narrow the search for the KT boundary, but also as a correlation tool. Cluster analysis shows two major and very distinctive palynological associations in Diablito (Fig. 6.16). One cluster is composed of the samples between 794.7’ and 1633.8’, and samples between 1635.7’ and 2244.4’ compose a nother cluster. In terms of palynological composition, the sample at 1633.8’ is more similar to the sample at 794.4’ than to the sample at 1635.7’ even the distance between them (~ 840 foot) is almost 400 times the distance between 1633.8’ and 1635.7’ (~ 2’). Also, the palynological composition of the sample at 1635.7’ is more similar to the sample at 2244.4’ even though the distance between them is ~ 610’. These results suggest deep changes in the composition of th e palynoflora between 1630’ and 1640’. According to the magnetic susceptibility analysis, this interv al is very close to where the Iridium anomaly and other evidence of the KT boundary would be located, demonstrating that the changes observed in the palynological composition are related with the KT boundary event. The number of species, referred to as Richness (S), is related to the sample size. Increasing the sample size increases the number of species (Rosenzweig, 1995). The recovery of palynomorphs is variable in the samples studied in Diablito and this difference could account for the differences found in S between the samples. In the 40 samples studied below 1635.7’ (Cretaceous samples) the mean number of pa lynomorphs counted was 249 individuals, with a minimum and maximum of 59 and 328 individuals, re spectively, and a standard deviation of 83.7. In the 42 samples studied above 1635.7’ (Paleocene samples), the mean number of palynomorphs counted was 191 individuals wi th a minimum and maximum of 15 and 324 individuals, respectively, and a st andard deviation of 120. The differences in the mean number of counted grains below and above the boundary is significant (t-test, p=0.013) indicating that

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80 number of palynomorphs counted in the Cretaceous is higher than the number counted in the Paleocene. The difference in S between the Cretaceous and the Paleocene could be the result of this difference. In the Paleocene, 14 samples of a total of 42 have < 100 grains. One possible explanation for the poor recovery in the Paleocen e is the effect that the KT boundary event had on the vegetation. Because of the environmental crisis, a high proportion of species and individuals were eliminated If this reasoning is true, an upward increase in the number of grains should be seen in the Paleocene. Samples immedi ately above the boundary are expected to have low recovery than samples upward in the section, which are expected to have more taxa as a result of the recuperation of the vegetation. However the number of grains counted in the Paleocene does not show any trend. Another explanation is that during the Paleocen e the vegetation was mostly dominated by a few species. In this scenario, the probability of findi ng individuals of the dominant species is higher than the probability of finding rare species. If this is true, a high value of dominance should be found in the Paleocene. Pielou’s evenness index (J) evaluates the variation in the species abundances among a community. When all the species have the same number of individuals, J is equal to 1 and when most of the individuals be long to very few species J tends to low values (Jaramillo, 2008). The mean J for the Paleocene samples is 0.66 with a minimum and maximum value of 0.12 and 0.92, respectively, and standard deviation of 0.16. This mean value of J is not significantly different from the mean J value of the Cretaceous samples (mean=0.64, min=0.36, max=0.85, sd=0.12) (t-test, p=0.63). According to these results, the low recovery of some of the Paleocene samples could not be satisfactorily explained by the evenness of th e Paleocene samples nor the effect of the KT boundary event on the vegetation. The distributi on and recovery of palynomorphs is also

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81 controlled by lithofacies, sample position in systems tracts and sample preservation (Holland, 1995) and these factors could explain the poor r ecovery in some of the Paleocene samples. Further analyses are necessary in order to test this idea. One way to account for the difference in the number of grains counted is rarefaction. A level of rarefaction of 100 grains was used a nd samples with < 100 grains counted were excluded from the analysis. Rarefaction analysis (Fig. 6.10) indicates that the Cretaceous samples tend to have a higher richness than Paleocene samples, regardless of the number of grains counted in each sample. Diversity indexes are a combination of th e richness as well as the distribution of individuals among the species and they allow comparisons among samples regardless of the original sample size (Rosenzweig, 1995). The Shannon index calculated for each sample indicates that there is a trend toward decreasing diversity from the Cretaceous to the Paleocene (Fig. 6.11) from a mean of 2.2 (standard deviation=0.48) in the Cretaceous to a mean of 1.79 (standard deviation=0.43) in th e Paleocene. One isolated Pale ocene sample (1438’) yielded a Shannon index of 0.29, fewer than all of othe r Cretaceous or Paleocene samples. However this sample could have a strong biofacies control (dominated by Proxapertites operculatus ) that may be producing this low value. Standing diversity was calculated in Diablito using the range through method that tends to eliminate facies and sample size effects. Singletons were not used in the analysis because they introduce noise and mask the diversity signal (F oote, 2000). The edge effect was removed from the analysis using a piecewise regression. The standing diversity shows a high diverse Cretaceous palynoflora abruptly replaced by a lo w diversity Paleocene assemblage, from a mean of 120 species (standard deviation=2.5) in th e Cretaceous to a mean of 83 species (standard

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82 deviation=10.6) in the Paleocene. The change in standing diversity is not sudden, but gradual and occurrs through a 20-foot interval. Taxonomic rates in the sense of Foote (2000) are sensitive to interval length. Diablito was subdivided into one million-time interval using graphic correlation and key stratigraphic datums compiled by Jaramillo et al. (2006). The pe rcapita origination rate shows high values in the two bin of the Cretaceous (Fig 6.18). Piece-wise regression analysis was used to remove the edge effect, however the marine influence at th e base of Diablito, as shown by the presence of dinocysts and foraminifera, spread upward the section the first appearance of most of the species of pollen and spores, and produce an extended edge effect. The effect is probably affecting all the Cretaceous, however in Figure 6.18 the last two bines of the Cretaceous were not removed for the graphic. The two first bin after the KT boundary show a decreasing trend in the origination rate, and from 1450’ to the top of the section the rate is stable. The Paleocene in Diablito is characterized by stable origina tion rates and nonsignificant changes above background levels. Only a few new species are reco rded in the Paleocene, suggesting that the time that the palynoflora needed to reach dive rsity values as high as those observed in the Cretaceous is beyond the record of Diablito. This result is supported by the standing diversity analysis that shows low diversity values during the Paleocene. The per capita extinction rate shows low va lues before the KT boundary. Suddenly the rate increases almost four times the values observed in the previous bin. The change is coincident with the interval where the KT boundary is locat ed and with the change in standing diversity, indicating that the increase in the extinction ra te is responsible for the change in standing diversity.During the Paleocene the extinction ra te is stable and non-significant changes are observed.

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83 The estimation of palynomorph extinction pe rcentages at the KT boundary depend on whether the measure is based on the megaflor a or palynological record (Nichols and Johnson, 2008). Even though leaves and paynomorphs are deri ved from the same vegetation source, their taxonomic resolution is different. Palynology ha s coarse taxonomic resolution; fossil pollen genera and species can be thought of as re presenting fossil botanical families and genera, respectively (Nichols and Johnson, 2008). On the other hand, megaflora provide high-resolution taxonomic data (Nichols and Johns on, 2008). Initial interpretations of the megaflora and pollen records of North America reflect extinction leve ls between 60-70% and 15-30%, respectively, at the species level (Wolfe & Upchurch, 1986). La ter analyses using quantitative methods and based on the disappearance of species in the uppermost 5m below the KT boundary, revealed extinction levels as high as 57% for the megafl ora and between 17 and 30% for the palynoflora (Wilf and Johnson, 2004). The range calculated fo r the palynoflora by Wilf and Johnson is almost identical to Hotton’s (2002) estimate for eastern Montana (USA). Hootn used a chi square analysis and found a percentage of extinction between 17-30%. A chi square analysis was performed to calculate the extinction percentage in Diablito. All the samples were included in the analysis. Ev ery species was classified as belonging to one of three categories and the extinction was calculated as the percentage of species occurring exclusively in the Cretaceous (K category) with respect to the number of species displaying non significant change across the boundary (KT cate gory), and the number of species in the K category. If all the species of pollen and spores are included in the analysis, the extinction percentage is 69%. If singletons (species occurring in only one sample) are removed from the analysis the percentage is 47%. This percenta ge is higher than the extinction percentage calculated for North America, suggesting that the change in vegetation was more severe in the

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84 tropics than in temperate latitudes. Is important to note that different approaches and methods have been used to calculate extinction leve ls making the comparison between studies more difficult. The changes in extinction between different places could be the result of the differences in the methodology used to calculate the extinction. The results of this study could support the hypothesis of a latitudinal extinction gradient, i.e. decreasing extinction with increasing latit ude (Wolfe and Upchurch, 1986; Upchurch, 1989). The patterns observed do not support the argument for attenuation of dama ge with increasing distance from the impact site (Nichols and Johnson, 2008). Diablito is located almost the same distance from the impact site as some of th e sections in North America (~4000km) and the effects in Diablito were higher. More sections of the KT boundary from the tropics are needed to test these hypotheses and to ma ke global generalizations.

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85 APPENDIX A PALYNOMORPH DISTRIBUTION IN SAMPLES FROM THE DIABLITO CORE Species FAD LAD # samples Achomosphaera sp. 1 2062.9 2062.9 1 Achomosphaera sp. 2 2244.4 2244.4 1 Achomosphaera sp. 3 1885.2 1885.2 1 Acritarcha 2018 1249.2 3 Andalusiella mauthei 1885.2 1517.5 2 Andalusiella spp. 2244.4 1727.1 2 Annutriporites iversenii 1965.5 1638.2 19 Apiculatasporites sp. 1731.8 1249.2 5 Apiculatisporites sp. 1 1849.4 1716.4 2 Apiculatisporites sp. 2 1506.7 1506.7 1 Araucariacidites sp. 2244.4 1565 15 Araucariacites australis 2244.4 1646 20 Arecipites sp. 1849.4 1849.4 1 Areoligera spp. 1550.5 1550.5 1 Ariadnaesporites spp. 2018 1633.8 4 Azolla spp. 1758.3 1758.3 1 Baculamonocolpites "amplius" 1732.1 1706 3 Baculamonocolpites "degradatus" 1752.9 1752.9 1 Baculamonocolpites "magnabaculatus" 1849.4 1849.4 1 Baculamonocolpites aff. multispinosus 2097.1 1672.8 7 Baculamonocolpites sp.1 1765.3 1765.3 1 Baculamonocolpites spp. 2097.1 1885.2 3 Baculatisporites "densinatus" 1849.4 1478.5 3 Baculatisporites "dual" 2018 1885.2 2 Baculatisporites "minor" 2244.4 2244.4 1 Baculatisporites "minutisimus" 931 794.7 2 Baculatisporites "perfectus" 1885.2 1885.2 1 Baculatisporites "reticularis" 1506.7 794.7 2 Baculatisporites sp. 2018 794.7 24 Baculatisporites sp.2 1941.4 1941.4 1 Baculatriletes "gemmatus" 1379 1379 1 Baculatriletes "minimus" 1707.7 1707.7 1 Baculatriletes sp. 1540.2 794.7 3 Bacumorphomonocolpites tausae 2018 2018 1 Bombacacidites "cortus" 1460.1 988.8 2 Bombacacidites aff. psilatus 1517.5 1506.7 2 Bombacacidites annae? 794.7 794.7 1 Bombacacidites sp. A 1018.5 988.8 2 Bombacacidites sp. B 1018.5 1018.5 1 Bombacacidites sp. C 1018.5 1018.5 1 Bombacacidites sp. D 896 794.7 3 Bombacacidites sp. E 950 950 1 Bombacacidites sp. G 931 931 1 Buttinia andrevi 2244.4 1638.2 2 Cerodinium diebelli 2018 2018 1

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86 Cerodinium pannuceum 2244.4 1941.4 4 Cerodinium sp. 2 2244.4 2244.4 1 Cerodinium spp. 2244.4 1638.2 5 Chomotriletes minor 2244.4 794.7 36 Cicatricosisporites "rugoides" 1601 1601 1 Cicatricosisporites sp. 1752.9 1752.9 1 Cicatricososporites "lofis" 1849.4 1478.5 2 Cingulatisporites sp.1 2097.1 2097.1 1 Cingulatisporites sp.2 2062.9 1478.5 2 Cingulatisporites sp.3 1478.5 1478.5 1 Clavainaperturites sp. 1707.7 1707.7 1 Clavamonocolpites "dispersus" 1646 1550.5 3 Clavatricolpites "disparis" 1438 1438 1 Clavatricolpites "minutidensiclavatus" 1179.6 794.7 5 Clavatricolpites densiclavatus 1614.6 1517.5 3 Clavatricolpites sp. 2097.1 2097.1 1 Clavatricolpites sp. 3 1696.3 1696.3 1 Clavatricolporites "baculatus" 1672.8 1635.7 2 Clavatriletes "magnicus" 1648.1 1648.1 1 Colombipollis tropicalis 2244.4 988.8 46 Concavissimisporites psilatus 1307.9 1307.9 1 Cordosphaeridium sp. 2244.4 1885.2 3 Corsinipollenites psilatus 1885.2 794.7 7 Corsinipollenites sp. 2244.4 858.2 2 Crassulina sp.1 1774.2 1574.1 3 Cricotriporites guianensis 1761.4 1646 3 Crusafontites grandiosus 2062.9 1849.4 5 Ctenolophonidites lisamae 1179.6 1179.6 1 Curvimonocolpites inornatus 1018.5 988.8 2 Cyclonephelium "fibrosum" 1849.4 1849.4 1 Cyclusphaera sp. 1965.5 950 2 Dinocyst und. 2244.4 931 15 Dinogymnium acuminatum 1821.5 1821.5 1 Dinogymnium sp. 1079.4 1079.4 1 Diporoconia cf. iszkaszentgyoergyi 1789.5 1641.3 2 Duplotriporites ariani 2097.1 1885.2 4 Echidiporites "docil" 1672.8 1672.8 1 Echimonocolpites "microechinataensis" 1550.5 1550.5 1 Echimonocolpites protofranciscoi 2244.4 1635.7 33 Echimonocolpites sp. 1599.5 858.2 5 Echimonocolpites sp. 2 2244.4 2244.4 1 Echimonoletes "gemmatus" 1941.4 1758.3 3 Echimonoletes sp. 1506.7 1179.6 3 Echimonoletes sp. 1 1638.2 1638.2 1 Echimonoletes sp. 2 2062.9 2062.9 1 Echimonoletes sp. 3 1696.3 1696.3 1 Echimonoletes sp. 4 1179.6 1179.6 1 Echimonoporites "specialis" 1672.8 1349.7 2 Echinatisporis "rojus" 2097.1 1400.6 9

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87 Echinatisporis sp. 2244.4 794.7 65 Echiperiporites? sp. 1965.5 1965.5 1 Echitricolporites sp. 1752.9 1752.9 1 Echitriletes "baculatus" 1941.4 1506.7 3 Echitriletes "densus" 1727.1 1727.1 1 Echitriletes "echinatus" 2244.4 2244.4 1 Echitriletes "gemmatus" 1765.3 1765.3 1 Echitriletes "intercolensis" 1970.7 1765.3 2 Echitriletes "papilospinosus" 1727.1 1727.1 1 Echitriletes "solaris" 1379 858.2 2 Echitriletes "spinosus" 1885.2 1849.4 2 Echitriletes sp. 1 2244.4 1379 6 Echitriletes sp. 3 2244.4 931 4 Echitriletes sp. 4 1356.8 1356.8 1 Echitriletes sp. 5 1527 1527 1 Echitriletes sp. 6 1626.2 988.8 4 Echitriletes spp. 2244.4 794.7 23 Echitriporites sp. 988.8 988.8 1 Echitriporites suescae 1991 1991 1 Echitriporites trianguliformis 2244.4 1179.6 62 Ephedripites "afropollensis" 2244.4 1672.8 6 Ephedripites "crucistriatus" 1758.3 1727.1 2 Ephedripites sp. 2062.9 1765.3 4 Ephedripites sp. 1 1849.4 1527 3 Ephedripites sp. 3 1574.1 1574.1 1 Ephedripites sp. 6 1849.4 1654.5 3 Foram linnings 2097.1 1540.2 10 Foveodiporites operculatus 1356.8 794.7 3 Foveodiporites sp. 931 931 1 Foveotricolpites perforatus? 931 858.2 2 Foveotricolpites sp. 1638.2 1638.2 1 Foveotricolporites sp. 1799.1 1647.4 2 Foveotriletes margaritae 2244.4 931 34 Gabonisporites vigourouxii 1849.4 1648.1 4 Gemmadiporites "diablensis" 1413.3 1349.7 2 Gemmamonocolpites "balonensis" 1761.4 1761.4 1 Gemmamonocolpites "megagemmatus" 1774.2 1774.2 1 Gemmamonocolpites "microgemmatus" 2018 1018.5 4 Gemmamonocolpites "minor" 1849.4 1706 2 Gemmamonocolpites "verrucatus" 794.7 794.7 1 Gemmamonocolpites dispersus 1965.5 1672.8 6 Gemmapollenites "difussus" 2062.9 2062.9 1 Gemmastephanocolpites gemmatus 1574.1 931 17 Gemmatisporis "densus" 1647.4 1249.2 2 Gemmatriletes "gemmatus" 1506.7 794.7 2 Gemmatriletes "granolaesuratus" 2018 1849.4 3 Gemmatriletes "indiferentis" 1565 1460.1 2 Gemmatriletes "scabratus" 950 950 1 Gemmatriletes spp. 1751.7 794.7 6

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88 Glaphyrocysta sp. 1 2244.4 2244.4 1 Hamulatisporis caperatus 1991 1641.3 14 Inaperturopollenites spp. 2244.4 1356.8 25 Ischyosporites sp. 1799.1 1799.1 1 L. proxapertitoides proxapertitoides 2244.4 896 42 L. proxapertitoides reticuloides 2062.9 1140.3 28 Laevigatosporites sp. 2244.4 794.7 51 Laevigatosporites sp. 1 1349.7 1249.2 2 Laevigatosporites sp. 2 1506.7 1506.7 1 Leiosphaera spp. 2097.1 1565 5 Longapertites "crassiperforatus" 1490.6 1490.6 1 Longapertites "echinatus" 1672.8 1506.7 2 Longapertites "minutifossulatus" 2018 2018 1 Longapertites marginatus 1506.7 931 6 Longapertites microfoveolatus 1400.6 794.7 9 Longapertites sp. 1 2097.1 1379 12 Longapertites vaneendenburgi 1752.9 931 14 Longitrichotomocolpites "microperforatus" 1550.5 1550.5 1 Longitrichotomocolpites sp. 1849.4 1574.1 5 Longitrichotomocolpites sp. 1 1641.3 1641.3 1 Magnastriatites "goleatus" 1991 931 3 Magnastriatites sp. 1727.1 1727.1 1 Margocolporites sp. 896 896 1 Mauritiidites franciscoi franciscoi 1179.6 794.7 11 Mauritiidites franciscoi var. pachyexinatus 931 858.2 2 Monocolpites "gigantispinosus" 2062.9 1672.8 7 Monocolpites "granulatus" 1750.5 1750.5 1 Monocolpites "verrucatus" 1965.5 1965.5 1 Monocolpites grandispinger 1991 1797.9 3 Monocolpites obtusispinosus 2062.9 1761.4 2 Monocolpites spp. 931 931 1 Monocolpopollenites "longiaperturado" 2062.9 896 6 Monocolpopollenites sp. 1970.7 1970.7 1 Monoporopollenites "foveolatus" 1849.4 1849.4 1 Monoporopollenites "microperforatus" 2244.4 2244.4 1 Monoporopollenites annulatus 1641.3 1018.5 5 Monoporopollenites sp. 1 1626.2 931 2 Odontochitina spp 1885.2 1885.2 1 Osmundacidites sp. 1490.6 1490.6 1 Palaeocystodinium sp. 2062.9 1885.2 3 Paleosantalaceaepites? sp. 1672.8 1672.8 1 Pediastrum spp. 2244.4 794.7 45 Perinomonoletes "acicularis" 1970.7 794.7 6 Perinomonoletes sp. 1885.2 1179.6 6 Periretisyncolpites giganteus 2097.1 1638.2 18 Periretisyncolpites giganteus var. minor 1249.2 1179.6 2 Polypodiaceoisporites "trilobatus" 1672.8 1672.8 1 Polypodiaceoisporites sp. 1 1517.5 1517.5 1 Polypodiaceoisporites sp. 2 1527 794.7 2

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89 Polypodiaceoisporites sp. 3 1614.6 1614.6 1 Polypodiaceoisporites sp. 5 896 896 1 Polypodiaceoisporites spp. 1614.6 896 4 Polypodiisporites sp. 1 1727.1 1727.1 1 Polypodiisporites sp. 2 1641.3 1641.3 1 Proteacidites dehaani 2097.1 1672.8 21 Proxapertites "gemmatus" 2244.4 1647.4 8 Proxapertites "sulcatus" 2097.1 1672.8 5 Proxapertites aff. "minutihumbertoides" 1941.4 1672.8 2 Proxapertites cursus 1018.5 794.7 2 Proxapertites humbertoides 1970.7 950 3 Proxapertites magnus 988.8 794.7 4 Proxapertites operculatus 2244.4 794.7 63 Proxapertites operculatus var. "reptilatus" 2062.9 1179.6 8 Proxapertites psilatus 2097.1 896 60 Proxapertites tertiaria 1991 931 2 Proxapertites verrucatus 1970.7 1638.2 12 Psilabrevitricolporites "circularis" 1249.2 1249.2 1 Psilabrevitricolporites "marginatus" 2018 2018 1 Psilabrevitricolporites "scabratus" 1249.2 1249.2 1 Psilabrevitricolporites simpliformis 1249.2 794.7 6 Psilabrevitricolporites sp. 1 1965.5 1965.5 1 Psilabrevitricolporites sp. 2 1605.8 1605.8 1 Psilabrevitricolporites sp. 3 1648.1 1648.1 1 Psilabrevitricolporites spp. 2097.1 1249.2 8 Psiladiporites sp. 1 1970.7 1550.5 6 Psiladiporites sp. 2 794.7 794.7 1 Psilamonocolpites "donensis" 1648.1 1648.1 1 Psilamonocolpites medius 2244.4 794.7 82 Psilamonocolpites operculatus 1965.5 794.7 13 Psilastephanocolpites "singularis" 1885.2 1821.5 3 Psilastephanocolpites sp.2 1249.2 1249.2 1 Psilastephanocolporites "ocularis" 1672.8 1672.8 1 Psilastephanocolporites "operculoverrucatus" 1751.7 1751.7 1 Psilastephanocolporites"syncolpatus" 1646 1646 1 Psilastephanoporites sp.1 1941.4 1849.4 2 Psilasyncolporites sp. 1638.2 988.8 2 Psilasyncolporites sp. 2 1626.2 1626.2 1 Psilatricolpites "arrowensis" 1849.4 1641.3 10 Psilatricolpites sp. 1 1821.5 1758.3 2 Psilatricolpites sp. 2 1849.4 1849.4 1 Psilatricolpites sp. 3 2062.9 1648.1 4 Psilatricolpites spp. 1774.2 988.8 6 Psilatricolporites "ampliexinatus" 1965.5 1750.5 4 Psilatricolporites "annulomarginatus" 1490.6 1490.6 1 Psilatricolporites "apendicatus" 1965.5 1965.5 1 Psilatricolporites "diablensis" 1991 1991 1 Psilatricolporites "grandis" 1646 1646 1 Psilatricolporites "marginalis" 1849.4 1849.4 1

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90 Psilatricolporites "poriannulatus" 1787.2 1787.2 1 Psilatricolporites sp.1 1638.2 1638.2 1 Psilatricolporites spp. 2062.9 794.7 27 Psilatriletes "arcuatus" 1506.7 1506.7 1 Psilatriletes < 25 2244.4 794.7 39 Psilatriletes > 50 2244.4 931 24 Psilatriletes 25-50 2244.4 794.7 82 Psilatriporites "minor" 1638.2 1638.2 1 Psilatriporites sp. 2 1849.4 1400.6 5 Psilatriporites sp. 3 1849.4 1849.4 1 Pteridacidites sp. 1 1018.5 1018.5 1 Pteridacidites sp. 2 931 931 1 Racemonocolpites racematus 2018 1356.8 13 Racemonocolpites sp. 2244.4 1506.7 8 Racemonocolpites sp. 2 1249.2 1249.2 1 Retibrevitricolporites "microperforatoides" 1941.4 1941.4 1 Retibrevitricolporites sp. 1 1787.2 1574.1 4 Retidiporites "elongatus" 1849.4 1638.2 5 Retidiporites "fossulatus" 1672.8 1672.8 1 Retidiporites "foveolatus" 1356.8 1356.8 1 Retidiporites "microperforatus" 2244.4 1706 9 Retidiporites magdalenensis 1356.8 794.7 12 Retidiporites sp. 1672.8 1605.8 2 Retidiporites sp. 2 1356.8 931 2 Retimonocolpites "gradatus" 2244.4 2244.4 1 Retimonocolpites "operculatus" 1885.2 1672.8 2 Retipollenites "afropollensis" 1706 1706 1 Retistephanocolpites sp. 1605.8 1605.8 1 Retistephanocolporites "ecuatorialis" 1307.9 1179.6 3 Retitrescolpites sp. 1 1885.2 1797.9 3 Retitricolpites "fortii" 1672.8 1672.8 1 Retitricolpites "minor" 1646 1646 1 Retitricolpites "reticularis" 1885.2 858.2 5 Retitricolpites "triangulatus" 1970.7 1970.7 1 Retitricolpites aff. "microreticulatus" 1991 1991 1 Retitricolpites spp. 1797.9 1647.4 2 Retitricolporites "ampliporatus" 1965.5 1752.9 2 Retitricolporites "finitus" 931 931 1 Retitricolporites "fossulatus" 2062.9 1970.7 2 Retitricolporites "gradatus" 1849.4 1849.4 1 Retitricolporites "marginatus" 1991 1638.2 2 Retitricolporites "minutus" 1941.4 1641.3 2 Retitricolporites sp. 1 1672.8 1672.8 1 Retitricolporites sp. 2 1647.4 1647.4 1 Retitricolporites sp. 4 1506.7 1506.7 1 Retitricolporites sp. 5 1018.5 1018.5 1 Retitricolporites spp. 2244.4 794.7 52 Retitriletes "bolonensis" 2244.4 2244.4 1 Retitriletes "cingulatus" 2244.4 2244.4 1

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91 Retitriletes "claris" 1727.1 1727.1 1 Retitriletes "minutus" 2244.4 1478.5 25 Retitriletes "verrucatus" 1506.7 1506.7 1 Retitriletes sp. 1799.1 1799.1 1 Retitriletes sp. 1 1941.4 1821.5 2 Retitriletes sp. 2 1731.8 1478.5 3 Retitriletes sp. 4 896 896 1 Retitriletes sp. 5 1761.4 1761.4 1 Retitriporites "spinosus" 1849.4 1849.4 1 Retitriporites sp.1 1965.5 1965.5 1 Retitriporites sp.2 1506.7 988.8 2 Rugomonocolpites "minoris" 1849.4 1849.4 1 Rugulatisporis "cerebroides" 1849.4 1849.4 1 Rugulatisporis sp. 1179.6 988.8 4 Rugulatisporites "rugulatus" 1941.4 1941.4 1 Rugulatisporites "tenuis" 1991 1991 1 Rugulatisporites sp. 1 1789.5 1789.5 1 Rugulatisporites sp. 2 1774.2 1732.1 2 Rugulatisporites sp. 3 931 931 1 Rugulatisporites sp. 4 2062.9 931 2 Rugulatisporites sp. 5 1727.1 1727.1 1 Rugulatisporites sp. 6 1849.4 988.8 2 Scabradiporites sp. 1752.9 1752.9 1 Scabrastephanocolporites "pachyexinataensis" 1849.4 1849.4 1 Scabrastephanoporites "sacabraporatus" 2062.9 2062.9 1 Scabratricolpites sp. 830.6 830.6 1 Scabratricolporites "psilatus" 1672.8 1672.8 1 Scabratriletes sp. 1638.2 794.7 4 Scabratriporites sp. 1349.7 1349.7 1 Senegalinium spp. 1970.7 1672.8 2 Spiniferites ramosus 1885.2 1885.2 1 Spiniferites sp. 2 1941.4 1941.4 1 Spiniferites spp. 2244.4 1550.5 7 Spinizonocolpites baculatus 2097.1 1638.2 34 Spinizonocolpites echinatus 1885.2 1751.7 5 Spirosyncolpites "gemmatus" 1112.2 1112.2 1 Stephanocolpites costatus 1991 1490.6 23 Striatopollis sp.1 1774.2 1774.2 1 Striatricolporites "specialis" 1774.2 1774.2 1 Striatricolporites perforatus 931 794.7 3 Striatricolporites sp. 2 950 896 2 Striatriletes sp. 1752.9 1752.9 1 Syncolpites "fossulatus" 1849.4 1849.4 1 Syncolporites aff. lisamae 1685.5 1249.2 2 Syncolporites lisamae 1799.1 1349.7 8 Syncolporites marginatus 1727.1 794.7 2 Syndemicolpites typicus 2097.1 1641.3 25 Terscissus canalis 1970.7 1179.6 5 Terscissus crassus? 1574.1 1574.1 1

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92 Terscissus sp. 1970.7 1356.8 4 Tetracolporites "annulatus" 1638.2 1478.5 2 Tetracolporites "operculoverrucatus" 1849.4 1849.4 1 Tetracolporites sp. 1799.1 1799.1 1 Tetracolporopollenites "duplex" 1672.8 1672.8 1 Tetracolporopollenites "perforatus" 1758.3 1671 5 Tetracolporopollenites aff. transversalis 1758.3 1638.2 4 Tetracolporopollenites sp.4 1970.7 931 4 Tetracolporopollenites spp. 1941.4 794.7 15 Tetradites sp. 1885.2 1647.4 2 Tetradites sp. 2 1648.1 1648.1 1 Tetradites umirensis 2062.9 1641.3 2 Thalassipora sp. 2097.1 2097.1 1 Tricolpites aff. microreticulatus 1758.3 1758.3 1 Tricolpites sp.1 1970.7 1970.7 1 Tricolpites sp.2 1614.6 1614.6 1 Tricolpites sp.3 1018.5 1018.5 1 Triporopollenites sp. 794.7 794.7 1 Trithyrodinium sp. 2062.9 2062.9 1 Ulmoideipites krempii 1991 794.7 20 Verrubrevitricolporites sp. 1685.5 1641.3 3 Verrucatosporites sp. 1 1765.3 1672.8 2 Verrucatosporites sp. 2 1727.1 1727.1 1 Verrucatosporites sp. 3 2097.1 2097.1 1 Verrucatotriletes "discretus" 1991 1991 1 Verrucatotriletes sp. 2 1716.4 931 4 Verrucatotriletes sp. 3 2244.4 794.7 6 Verrucatotriletes sp. 4 2018 1527 3 Verrucatotriletes spp. 2244.4 794.7 6 Verrutriletes "magnoviruelensis" 2062.9 950 9 Verrutriletes "viruelensis" 2244.4 794.7 44 Verrutriporites sp. 1751.7 1751.7 1 Zlivisporis "gibraltarensis" 1849.4 950 2 Zlivisporis blanensis 2244.4 1249.2 22

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93 APPENDIX B ILUSTRATION OF PALYNOMORPHS 1 Annutriporites iversenii 2 Terscissus canalis 3 Hamulatisporis caperatus 4 Crusafontites grandiosus 5 Diporoconia cf. diporoconia iszkaszentgyoergyi 6 Spinizonocolpites echinatus 7 Duplotriporites ariani 8 Azolla spp 9 Racemonocolpites racematus 10 Perinomonoletes acicularis 11 Proteacidites dehaani 12 Periretisyncolpites giganteus 13 Psilabrevitricolporites simpliformis 14 Ulmoideipites krempii 15 Corsinipollenites psilatus 16 Ctenolophonidites lisamae 17 Echimonocolpites protofranciscoi 18 Foveotriletes margaritae 19 Longapertites vaneendenburgi 20 Zlivisporis blanensis

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96 LIST OF REFERENCES Alvarez, L. W., Alvarez, W., Asaro, F., Mi chel, H. 1980. Extraterrestrial cause for the Cretaceous-Tertiary extinction. Science 208:1095-1108. Archibald, J. 1995. Testing extinction Theories at the Cretaceous-Tertiary boundary using the vertebrate fossil record. Pp. 373-393. In N. Mac Leod, Keller, G, ed. Cretaceous-Tertiary Mass Extinctions: Biotic and Environmental changes. W.W Norton & Company, New York-London. Archibald, J. 1995. Testing Extinction Theories at the Cretaceous-Tertiary boundary using the vertebrate fossil record. Pp. 373-397. In N. Mac Leod, Keller, G, ed. Cretaceous-Tertiary Mass Extinctions: Biotic and Environmental changes. New York-London. Arens, C. A., Jahren, A.H., Amundson, R. 2000. Can C3 plants faithfully record the carbon isotopic composition of atmospheri c carbon dioxide? Paleobiology 26:137-164. Armstrong, H. A. 2000. Quantitative Biostratigraphy. In D. A. T. Harper, ed. Numerical Paleobiology Computer-based Modelling and Anal ysis of Fossils and their Distributions. John Wiley & Sons. Berling, D. J., Royer, D.L. 2002. Fossil Plants as indicators of the Phanerozoic Global Carbon cycle. Annu. Rev. Earth Planet. Sci 30:527-556. Bohor, B. F., Foord, E.E., Modreski,P.J., and Triplehorn,D.M. 1984. Mineralogic evidence for an extraterrestrial impact event at the Cr etaceous-Tertiary boundary. Science 224:867-9. Bohor, B. F., Modreski,P.J and Foord,E.E. 1987. Shocked quartz in the Cretaceous-Tertiary boundary clays: evidence for a global distribution. Science 236:705-9. Boltovskoy, D. 1988. The range-through method and fi rst-last appearance data in paleontological surveys. Journal of Paleontology 62:157-159. Bottke, W. F., Vokrouhlicky, D., Nesvorny, D. 2007. An asteroid breakup 160 Myr ago as the probable source of the K/T impactor. Nature 449:48-53. Braman, D. R., Sweet, A.R., Lerbekmo, J.F. 1999. Upper Cretaceous-Lower Tertiary lithostratigraphic relationships of three core s from Alberta, Saskatchewan and Manitoba, Canada. Can. J. Earth Sci 36:669-683. Carlisle, D. B. 1992. Diamonds at the K-T boundary. Nature 357:119-120. Cooper, R. A., Crampton, J.S., Raine, J.I., Grandstein, F.M., Morgans, H.E., Sadler, P.M., Strong, P.C., Waghorn, D., Wilson, G.J. 2001. Quantitative Biostratigraphy of the Taranaki Basin: New Zealand: A determinis tic and probabilistic approach. AAPG Bulletin 85:1469-1498.

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105 BIOGRAPHICAL SKETCH Felipe de la Parra was born in Bogota, Colomb ia. The youngest of three children, he grew up mostly in Bogota, graduating from Colegio Ca fam in 1996. He earned his B.S in geology and his M.S in geology from the Universidad Naciona l de Colombia and University of Florida, respectively. Upon graduating in December 2001 with his B.S. in geology, Felipe entered to the Instituto Colombiano del Petroleo to work as a ju nior palynologist. Then he moved to Panama to work in the Smithsonian Tropical Research Institute. Upon completion of his MS program is spring 2009, Felipe will be working in th e Instituto Colombiano del Petroleo.