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STATE OF FLORIDA STATE BOARD OF CONSERVATION DIVISION OF GEOLOGY FLORIDA GEOLOGICAL SURVEY S Robert O. Vernon, Director SPECIAL PUBLICATION NO. 12 VERTEBRATE FOSSIL LOCALITIES IN FLORIDA By Stanley J. Olsen Tallahassee 1965 107960 CMI)(( inapt,c ript r( revived \Ilreh 23, 1965 1r i n Ied I,% the 11' 7,11ri ( t n 01 C o it I St~rv ey t Tall,~.~l llalllilslip T(ev ir '1; I ~i~ii iS CONTENTS Introduction... ...................... .. ... ...... ... .... ..... 1 W here fossils are found .............................................................. ......... 2 Rare occurrences of older sub-surface fossils in Florida .................. 4 Eocene surface localities ............................ .................... .. ........ 6 Oligocene surface localities ............... ............. ............. 9 Miocene surface localities ............ .. ............................................. 10 Pliocene surface localities .................. ............................................ 13 Pleistocene surface localities ................ .......................................... 15 Prospecting for fossils ....................................................... 17 Collecting fragile fossil bones ................................... 19 M materials ..................... ...................................... .... .... ... 19 Uncovering the specimen ................ ............ .............. 23 Preparing block for jacketing .............. .. .......... ......... ........... 24 Jacketing the block ..... ......... .. ............. ........................... 24 R e fe re n c e s .............. ...................... ............. .................... ......... ................ 2 8 ILLUSTRATIONS Figure 1 Age chart ........................................ .... .. ..... .... .......... .......... 3 2 Florida's oldest vertebrate fossil ............................................ 5 3 Why there are no dinosaurs in Florida ................................. 4 Map of eocene vertebrate localities ......................... ............ 8 5 Map of oligocene vertebrate localities .................................... 9 6 Map of miocene vertebrate localities ................ .... ............ 10 7 Map of pliocene vertebrate localities .......................... .......... 1 8 Map of pleistocene vertebrate localities ..................................... 16 9 Mining methods in phosphate pits ................................... ........... 18 10 How vertebrate fossils are collected ................. ................ 20 11 Fossil collector's field kit ............................................. ............. 21 VERTEBRATE FOSSIL LOCALITIES IN FLORIDA By Stanley J. Olsen INTRODUCTION Florida is one of the few states that attracts tourists who desire to spend a good portion of their vacation time collecting fossils. This is partially due to the accessibility of a number of fossil beds which are located on Florida's beaches and are con- stantly being eroded and exposed by the ever present surf action. This is particularly true in the Jacksonville Beach area and at Naples beach on the west coast. Here the fossil hunter can com- bine ocean bathing with fossil collecting, picking up the animal bones and teeth that are revealed on the beaches with every rise and fall of the tide. This can be a family sport, using mask, flip- pers and snorkel to add pleasure to this sort of beach collecting. For the more hearty and properly trained diver, Florida's river bottoms offer many fine collecting spots that can be reached with scuba gear and yet not place the diver beyond the 30-foot depth where decompression tables must be closely adhered to. Many dry prospecting localities are available in abandoned limestone quarries and sump pits, or in roadcuts where outcrops have been exposed by road grading equipment. In coastal areas where bay bridge approaches and span supports are constructed by dredging underwater sediments and using this material to build up artificial islands, the drained clays and sands of the beaches of these islands contain many fine, well preserved vertebrate fossils. Talks with landowners, on whose properties fossil-collecting localities occur, have established that a sure way to bring about the closing and posting of an area to collectors is to leave gates open, drop cigarettes in the grass, scatter lunch litter on the ground or climb over fences having locked gates. Treat the pro- perty rights of others as you would like to have your property rights regarded. These foregoing statements pertain to the lands of large commercial open-pit mining companies as well as to the small plot of land or seacliff of the solitary citizen. It cannot be too strongly emphasized that in all instances permission must be obtained before entering private property to prospect, whether the area is being actively worked or has been 1 107960 FLORIDA GEOLOGICAL SURVEY abandoned for many years. Water-filled quarries are particularly hazardous to lone prospectors or to parties accompanied by small children and suitable precautions should be taken to prevent acci- dents. Only the most foolhardy collector will use scuba gear in such a way to endanger his life. This last statement pertains to cave diving or to diving in deep silt-bottomed sinkholes. The many deaths due to this kind of diving are sufficient evidence of the probability of accident in this sort of venture. WHERE FOSSILS ARE FOUND Fossils may be defined as the remains or traces of any recog- nizable organic structure preserved since prehistoric time. In Florida, vertebrate fossils are usually limited to bones or partial bones and teeth of animals. Occasionally a completely articulated skeleton is found. These fossil bones or teeth may be altered by replacement by petrifying materials such as silica, calcium car- bonate or iron sulphide, to name but a few. In the more recently extinct forms, the fossils may show little or no difference in color, weight or texture when compared with the bones of living species. Florida's fossil-producing beds are classed as sedimentary deposits. This is to say that these beds were formed by the action of wind and water and were laid down as sediments, in the bottoms of rivers, lakes and seas. The bulk of the sedimentary strata in Florida, from which vertebrates are obtained, are present as lime- stones and range in age from Eocene through Miocene (fig. 1). The more recent are generally composed of sands and clays. Most of Florida's fossil-producing deposits of Eocene and Miocene age are of marine origin and have yielded few vertebrates. Quarries of Miocene Age that have produced terrestrial vertebrate remains, complete enough to be used in interpreting Florida's past animal life, are few in number. However, scarce as they may be, terrestrial Miocene vertebrates are better represented from Flo- rida's strata than they are from any deposit east of the Mississippi River. The bulk of the Miocene beds in the eastern United States, known outside Florida, are dominantly marine and have produced few terrestrial fossils. The animal population in Florida must have approached its peak during Pleistocene times if we are to judge by the countless remains of animals of this age that are present in Florida's fossil beds. ERA PERIOD AGE VERTEBRATE BEGINNINGS OF RECENT C PLEISTOCENE E MILLION YEARSAGs O PLIOCENE N 1 MILLIONYEARSAGO A 0 MIOCENE M Z 20 MILLION YEARS AGO M 0 OLIGOCENE A 35 MILLION YEARS GO EOCENE C 60 MILLION YEARS AGO PALEOCENE 80 MILLION YEARS AGO CRETACEOUS 120 MILLION YEARS AGO JURASSIC 155 MILLION YEARS AGO TRIASSIC 190 MILLION YEARS AGO BIRDS MAMMALS + 4 PERMIAN 215 MILLION YEARS AGO PENNSYLVANIAN 250 MILLION YEARS AGO MISSISSIPPIAN DEVONIAN ,,, 350 MILLION YEARS AGO SILURIAN 390 MILLION YEARS AGO ORDOVICIAN 480 MILLION YEARS AGO CAMBRIAN 550 MILLION YEARS AGO REPTILES AMgPHIBIANISh FISHES I ONLY THESE BEDS OCCUR AS SURFACE FORMATIONS IN FLORIDA DINOSAURS NO VERTEBRATES KNOWN FROM DEPOSITS OLDER THAN THESE Figure 1. Age chart. . FLORIDA GEOLOGICAL SURVEY Perhaps one of the questions most often asked of Florida's paleontologists is, "where can fossils be collected in Florida?" Although the age range of Florida's fossil deposits isn't too great (Eocene through Pleistocene) when compared with our western states, the bones occur under a variety of conditions, some of which pose particular problems to the collector and prospector. Some of these circumstances are peculiar to Florida alone. RARE OCCURRENCES OF OLDER SUB-SURFACE FOSSILS IN FLORIDA Two occurrences of fossil animals from the deep sub-strata of Florida should be mentioned, since they represent animals from age groups not present as surface outcrops in Florida. During the summer of 1955, the Amerada Petroleum Corpora- tion drilled an exploratory well approximately 12 miles northwest of Okeechobee. In a well core that was recovered from a depth of 9,210 feet were the remains of an aquatic turtle of Cretaceous Age (fig. 2). The drill bit just happened to be in a position to penetrate the spot in which the bones of a fossil turtle were em- bedded. The recovered core, of gray argillaceous dolomite, was only 4 3/8 inches in diameter, but enough of the turtle's skeleton was recovered to establish that it was a water dwelling form. Only the anterior or front end of the reptile was recovered. The skull, as well as the hind portions, was outside the area of the core. Fossil turtles are not commonly found, even in formations that are exposed at the surface of the ground. When you consider the chances against placing a drill bit in a position so that it will penetrate a small skeleton at a depth of over 9,000 feet, it is even more remarkable that this singular specimen was ever re- covered. A similar chance recovery was made in Madison County, Florida by the Hunt Oil Company in 1944. In this instance, the drill core was brought up from a depth of 4,628 feet and contained a Middle Ordovician trilobite (Colpocoryphe exsul). A trilobite is a primitive crab-like arthropod. Trilobites attained their maximum development during the Cambrian and Ordovician and became extinct at the end of the Permian (215 million years ago). They are a useful index fossil used in determining the age of the beds in which they occur. SPECIAL PUBLICATION NO. 12 Figure 2. Florida's oldest vertebrate fossil. In both of the related instances, the animals came from deeply buried formations that are much older than any surface beds from which a fossil collector might prospect for fossils. The oldest surface rocks in Florida are of Eocene Age (60 million years old) and represent only a small portion of the sedi- ments which make up the sub-surface of Florida. FLORIDA GEOLOGICAL SURVEY It is not uncommon to receive large bones of Pleistocene ani- mals (mostly those of mastodons or mammoths) that are sent to the Florida Geological Survey with a request for additional infor- mation on these "dinosaur bones". Dinosaurs did not survive beyond the Upper Cretaceous (120 million years ago), and of course their remains are not found in rocks that are younger than the Cretaceous. Since formations of the correct age to contain dinosaur bones are only found many thou- sands of feet below the surface of Florida, it is not likely that any dinosaur bones will ever be recovered from this state (fig. 3). The closest surface formations of Cretaceous Age lie beyond the north Florida border, some 100 airline miles. It is possible, but not probable, that a well core (as in the case of the turtle and trilobite) could penetrate a dinosaur skeleton if all other conditions for its preservation were met beforehand. EOCENE SURFACE LOCALITIES The Eocene deposits of the western United States have yield- ed countless scientifically important specimens of early mammals. Among these is perhaps the most well known form, Hyracotherium ("Eohippus"), the ancestral four-toed horse. Beds of this age in Florida have produced only a few marine vertebrates. To date, none of those better known forms collected from terrestrial Eocene beds of Wyoming have been discovered in Florida's sediments, and presumably Florida's Eocene deposits contain no terrestrial vertebrates. Remains of the whale-like Basilosaurus or Zeuglodon are known from several widely scattered localities in north Florida. This marine mammal attained a length of over 40 feet and had a body that was well adapted to speed and maneuverability in wa- ter. Although shark teeth are known from the same beds as those that contain the teeth of Basilosaurus, the latter are distinguish- able by a characteristic step-edged or serrate-edged margin along the cutting edge of the tooth. The bones of this large mammal are readily seen in the cream-white matrix as they are generally a blue-black color and present a striking contrast to the surrounding limerock. Some of the vertebral elements are as large as those of the common whales that occur in the later Pleistocene deposits. Nearly every Basilosaurus find has been the result of commer- cial rock-quarrying operations in the open pits of Alachua, Gil- christ, Suwannee, Taylor and Jackson counties (fig. 4). There is Figure 3. Why there are no dinosaurs in Florida. 8 FLORIDA GEOLOGICAL SURVEY Miles 10 5 0 20 40 6 ga 18 o A L A B A M A App~E~Sal SMarianna c. F O R G I A Gulf Mexico Marianna, Jackson County Mayo,Taylor County Branford, Suwannee County .&b. , Buda, Alachua County Figure 4. Map of eocene vertebrate localities. no reason why this general area should not produce these fossils in quarries that are located in limestones of the Crystal River Formation. Collecting in rock quarries is particularly dangerous and proper safety precautions should be exercised after permission is obtained to enter the premises on which the pits are located. SPECIAL PUBLICATION NO. 12 OLIGOCENE SURFACE LOCALITIES As with the Eocene beds in Florida, all of the reported out- crops of Oligocene Age in Florida are of marine origin. The known fossil-bearing beds are of cream-colored limestone and are located in a comparatively small area near the town of Marianna in Jackson County (fig. 5). Only teleost or bony fish remains have been col- lected from the Jackson County limestones. Fossil-producing out- Mles 1050 20 40 6L Bp 1Q Approx Scle A L A B A M A 7 ---y _ R G I A Frantic Gulf Mexico OLIGOCENE VERTEBRATE FOSSIL LOCALITY Marianna,Jackson County (Marine,Fish only) Figure 5. Map of oligocene vertebrate localities. FLORIDA GEOLOGICAL SURVEY crops occur in this area mainly as low, weathered roadcuts, as excavated and graded highway bridge approaches, or in rock quar- ries. MIOCENE SURFACE LOCALITIES The richest bone bed of Miocene Age in eastern North Ameri- ca, the Thomas Farm Fossil Quarry (fig. 6), is located in Gilchrist County, near the town of Bell, in a most unpromising appearing A L A B A M A Gulf Mexico ) Alum Bluff, Liberty County '- ) Chattahoochee,Gadsden County ( Floridin Co.,Quincy,Gadsden County * SFullers Earth Co., Midway, Gadsden County T Griscom(Luna)Plantation,Leon County STallahassee Waterworks,Tallahassee, Leon County S.A.L.R.R.,Switchyard B,Tallahassee,Leon County ) Thomas Farm QuarryGilchrist County ( Franklin Phosphate Co.,Pit No.2,Newberry,Alachua County ) Colclough Hill,Alachua County SPhosphate Pits (In part),Polk County Figure 6. Map of miocene vertebrate localities. SPECIAL PUBLICATION NO. 12 setting of low, sandy, flat land having none of the "usual" sur- face outcrops with which fossil vertebrates are generally asso- ciated. The animals from this sinkhole or stream-cavern deposit are a mixture of terrestrial forms such as the small three-toed horse Parahippus, the large bear-like dog Amphicyon, numerous small carnivores, camels and many snakes, rodents and birds. Some aquatic forms are also present such as an alligator, turtles, frogs and siren remains. The story of the discovery of this important locality and the people who have worked it are contained in several publications, but particularly in the Florida Geological Survey Special Publication Nos. 5 and 6. The tract of land on which the fossil quarry is located is owned by the State of Florida and written permission must be secured from the head of the Biology Department of the University of Florida before one can visit the property. A caretaker is in residence. Five rather important Miocene localities lie in or around the Capitol City of Tallahassee (fig. 6). The Griscomb Plantation, or Luna Plantation, as it is generally known today, is located about 15 miles north of Tallahassee in Leon County. This planta- tion is the site of an early Miocene vertebrate locality that was accidently discovered in 1916 during the course of digging a shaft for a water well or cistern. This shaft, having a diameter of six or eight feet, was dug to a depth of 50 feet before it had to be abandoned due to encountering poisonous gas. The workmen had struck a bone-bearing layer just before the pit was abandoned, which produced the types of the Miocene horse Parahippus leonen- sis, and the dog-like carnivore Cynodesmus iamonensis. The well was completed by the use of a mobile drill rig and the larger hand- dug shaft was filled in around the well casing. No additional bone fragments were collected. This bone-bearing layer does not out- crop on the surface in the vicinity of the plantation and since the original well site is now within the landscaped area of the planta- tion headquarters, it is improbable that any additional material will be obtained from this locality within the foreseeable future. As in the case of the Griscomb Plantation, the digging of a pump pit by the Tallahassee Water Works was responsible for some very tantalizing fragments of the Miocene rhinoceros Aphe- lops, and of a camel Nothokemus. These meager scraps were collected in 1930 and here again, as with the Griscomb Plantation FLORIDA GEOLOGICAL SURVEY locality, the bone-bearing layer is no longer available for further exploration. In 1963, a deposit of middle Miocene Age was discovered while excavating to enlarge a switch yard of the Seaboard Airline Railroad Company in Tallahassee. This bone deposit represents a Miocene shoreline and the bones are a mixture of terrestrial and marine vertebrates inter- mingled with the shells of an ancient oyster bar. Two storks, heretofore unknown in the Western Hemisphere, are also recorded from this railroad-cut fossil bed. Two Miocene localities, a short distance west of Tallahassee, are from open-pit fullers earth mines. These are located at Quincy and Midway in Gadsden County. The first of these localities, at Quincy, produced Florida's first identifiable material of the Mio- cene horse, Merychippus. From the second Gadsden County site, Midway, were recorded scraps of the horse Parahippus, as well as those of Merychippus, and of the camel Nothokemus. Both of these localities are now in abandoned, water-filled pits. The sur- rounding country is covered by vegetation so that little hope is held for any additional fossils being obtained from the immediate vicinity of these original locations. The steeply sloping banks of Alum Bluff on the east bank of the Apalachicola River in Liberty County have long been known as a plant and invertebrate fossil locality. Recently, fragments of Parahippus and a gavial were collected from this steep-sided river bank. The bluffs above the Jim Woodruff Dam near Chattahoochee in Gadsden County have yielded a Parahippus tooth, numerous shark and ray teeth and few oyster shells. This locality was apparently close to a tidal zone in Miocene times. Colclough Hill, a roadcut near the University of Florida in Gainesville (fig. 6), has been a collecting spot responsible for fragments of the small Miocene horse Parahippus blackbergi and some shark and ray teeth. No articulated skeletons or complete large mammal bones have been recovered from this Alachua County locality. A number of years ago in Pit No. 2 of the Franklin Phosphate Company's mine near Newberry in Alachua County (fig. 6), a small bone-bearing pocket was discovered. This pocket offered many tantalizing fragments of Miocene mammals. Additional specimens SPECIAL PUBLICATION NO. 12 have been collected in other pockets in the general area of New- berry. Solution pits in the limestone quarries of Newberry and Haile have also acted as catch basins for Pliocene and Pleistocene vertebrate fossils, some of which are remarkably complete. Many of the early quarries are now grown over with vegetation or are water-filled. However, new areas are constantly being opened to mining operations and will bear close watching for new fossil discoveries. The phosphate pits of Polk County (fig. 6) have long been a favorite collecting region for both professional and amateur fossil hunters. The animals range in age from Eocene on through the Miocene and Pliocene with a number of Pleistocene and sub-Recent forms also having been recovered. It is only in recent months that any attempt has been made by the commercial mining companies to establish the stratigraphic position in which the remains occur. It is now hoped that animals and their associated strata can be studied in more detail so that data of stratigraphic importance can be compiled and analyzed. Sump pits tend to crust over and leave a hazardous under- lying quicksand; therefore, it is important that the collector seek out information on the area to be prospected from a field represen- tative of the company owning the pit as well as permission to enter the area. PLIOCENE SURFACE LOCALITIES Beds of Pliocene Age are rare indeed in Florida. Many depo- sits that contain vertebrates of Pliocene Age also have a mixture of Miocene and Pleistocene animals. This is particularly true of the phosphate beds of Polk and the surrounding counties in central Florida. However, there are several bone beds that contain fossils of vertebrate animals that occur elsewhere in the world in strata that has been determined to be of middle Pliocene age. The town of Haile is in reality little more than a place name on the Alachua County maps (fig. 7). The general Haile area is dotted with limerock pits. It is from one of these quarries that many small Pliocene vertebrates have been reco-ered. In Levy County, northeast of Williston, a quarry known as Mixon's Bone Bed has produced the remains of a proboscidean, Serridentinus, a rhino- ceras, Teleocerus, a horse, Hipparion and a camel, Procamelus. This quarry is on private land and has not been worked for some ears. FLORIDA GEOLOGICAL SURVEY A L A B A M A G E O R G I A Gulf of Mexico Haile,Alachua County ( Newberry,Alachua County Williston,Levy County ) Phosphate Pits(In part) Polk County Figure 7. Map of pliocene vertebrate localities. A newly discovered quarry, the McGehee Farm Site, has been reported by members of the staff of the University of Florida and is being worked by that institution. This fossil quarry is north of Newberry and a preliminary faunal list includes nine reptiles, three genera of birds, and eighteen mammals. Present among the reported mammals are the carnivore, Osteoborus, a proboscidean, Serridentinus, rhinos, Teleoceras and Aphelops and the horses Hipparion, Nannippus and Neohipparion. Also present are the camels Pliachenia and Megatylopus. This important site should prove to be more valuable scien- tifically as additional work is carried out. SPECIAL PUBLICATION NO. 12 PLEISTOCENE SURFACE LOCALITIES It is only natural that the most recent fossil animals, those of the Pleistocene, or Ice Age, should be the best known and most widely distributed in the State. The stream and swamp deposits in which their remains are preserved have not been so deeply buried as to be inaccessible nor, like most of the older beds, so long attacked by rivers and oceans as to have been largely eroded away and their contents lost or redeposited. The abundance of animals in Florida at this time was extra- ordinary. It can only be compared with the big game region of the Serengetti Plains of Africa in the early 1900's. The occurrence of Pleistocene animals is state-wide (fig. 8). Hardly a roadcut, realignment of a drainage ditch or the dredging of a channel can be undertaken without at least some Pleistocene animal remains being brought to light. The many shell marl dragline pits in the St. Petersburg and Bradenton areas are known to be good collecting areas. The drain- ed spoil banks have been responsible for many fine specimens of our smaller mammals and birds. The bridge approaches and marinas are also possible areas to be scrutinized, as are the beaches of Jacksonville and Mayport on the east coast and Naples on the Gulf coast. Rock fissure fills in both abandoned and active quarries in the Haile, Arredondo and Reddick areas have been natural collect- ing traps for many of our better known small Pleistocene animals. At Vero Beach and Melbourne, the surface beds have produced the only human remains in association with extinct Pleistocene animals. It is not improbable that more human remains will turn up as the number of collectors increases. Most of the clear rivers of north Florida cut through sediments of Pleistocene Age and it is not difficult to obtain a good repre- sentative collection of Pleistocene animal bones from the bottoms of these streams. Scuba gear used with accepted safety practices is all that is needed. Springs and sinkholes have been responsible for the deaths of many large Pleistocene animals and quite a few of their bones are now in museum collections throughout the state of Florida and in other parts of the United States. FLORIDA GEOLOGICAL SURVEY A L A B A M A ( Reddick,Marion County c ( 2 Melbourne, Brevard County PAA O ) Vero, Indian River County 2 SNaples,Collier County (5 Bradenton, Manatee County () St.Petersburg,Pinellas County ff-shore dredging HRE () Seminole Field, Pinellas County Lnd Dragline pits ( Arredondo,Alachua County 5C P. (9) Haile,Alachua County L G RIVERS and SPRINGS i Wakulla Springs, Wakulla County ( Aucilla River, Jefferson-Taylor County Line Itchtucknee River and Springs, Columbia-Suwannee County Line & Santa Fe River, Gilchrist-Suwannee-Columbia County Line ( Hornsby Spring, Alachua County r . () St.Johns River(Spoil banks), Duval County Peace Creek, De Soto County A P '- CAVES OMarianna Area, Jackson County (lron Ladder, Citrus County Saber-Tooth,Citrus County Figure 8. Map of pleistocene vertebrate localities. A number of divers have lost their lives in the dangerous sport of spring and sinkhole diving. I cannot stress too strongly that diving in springs and sinkholes is not recommended and should be discouraged for all but highly trained and well organized ex- ploring parties. Limestone caves in central Florida and a few in the Panhan- dle have also been prospected profitably in regard to cave-dwelling vertebrates. It is from a Reddick cave that the only remains of the Vampire Bat Desmodus have been recovered. SPECIAL PUBLICATION NO. 12 As with springs and sinkholes, cave exploring is a highly special- ized game and should not be indulged in as a part-time venture. It is safe to say that in regard to Pleistocene animals, any operation that disturbs the soil covering of Florida is worthy of close attention, as some fossil will most likely be located if enough attention is given to the matrix as it is being moved. PROSPECTING FOR FOSSILS Prospecting for fossil vertebrate animals in Florida is limited because of the lack of surface exposures or outcrops that are so familiar to bone hunters in other parts of the United States. Natural outcrops that produce bones are nearly non-existent; therefore, the prospector and collector must go to areas where excavations are being conducted or have been carried on. Lime- rock and mineral quarries (fig. 9), road cuts, and dredging opera- tions are responsible for the majority of the recent fossil finds of importance. Natural river or tide action, particularly if the action is aided by storms, occasionally brings to light fossil skeletons that are entombed in their confining banks or cliffs. More important than finding a tooth or single bone lying on the eroded surface or stream bottom is to locate, if possible, the source of the specimen from whence it came so that perhaps an entire skeleton or skeletons might be located and collected. Once a skeleton or skull is encountered, proper precautions must be taken to insure that it is preserved and collected to prevent fur- ther damage to the animal. All such finds should be reported to the geological survey or to established museums in order that proper precautions will be taken, and that the specimen will even- tually become a part of an organized collection where it will be carefully preserved and made available to research workers and professional scientists. If this is not possible, it is far better that the animal be collected by a conscientious amateur than to have it lost for all time and be of use to no one. It is worth repeating that wandering over land being excavated by commercial machinery, or on sediments that have recently been dredged, is foolhearty. In no instance should prospecting and collecting be attempted without first talking to the field super- intendant or construction foreman and obtaining their permission. 18 FLORIDA GEOLOGICAL SURVEY Vertebrates uncovered by phosphate mining BONE VALLEY AREA " 'W- OT fARLY 1900s Figure 9. Mining methods in phosphate pits. SPECIAL PUBLICATION NO. 12 There are plenty of areas that are deserted and clear of work crews and danger so that one does not have to endanger one's life by working close to a construction project. COLLECTING FRAGILE FOSSIL BONES Occasionally it is desirable to remove fragile fossil verte- brates from the area in which they were discovered with a minimum of delay. This may be due to the danger of being destroyed by mining operations or to the position of the specimen in, for exam- ple, a river bank at low water. In the event it isn't possible to contact a museum worker or professional paleontologist, it is better to have the recovery attempt made by a local interested party than to have the specimen lost or damaged beyond repair. For about 70 years, vertebrate paleontologists have been employ- ing a technique (enclosing specimens in plaster jackets) which, under some circumstances, should prove useful to archaeologists as well (fig. 10). This method has been described in a few publi- cations, but in general, it has been passed along from one acade- mic generation to the next by demonstration and instruction, and new modifications have been presented informally. The following technique is generally reserved for skulls or partially (or completely) articulated skeletons rather than the commonly found isolated bones or teeth that are more or less durable and will withstand handling in the field (fig. 10). MATERIALS There are a number of materials not normally stocked by the amateur paleontologist, which are necessary for this method. A complete prospector's field kit is illustrated in figure 11. 1. Burlap.. A suitable quantity and quality of this material can usually be obtained from the local feed store in the form of empty sacks. Depending on the geographic location they are vari- ously known as gunny bags, tow sacks and "croaker" sacks. The more loosely woven sacks for the coarsely ground livestock feeds are the most satisfactory since they permit the plaster of paris to thoroughly penetrate the weave. For cutting into strips the sacks should be opened out. This is done either by ripping the seam or unsewing by turning the sack wrongside out and starting at the bottom corner. The latter method is faster and easier. After the sack has been opened out, you have a nearly square sheet of burlap, which is now ready to cut into strips. This can be easily done by one person by placing one foot on one edge of the sheet, A 0 t. 0 Ci ~----- pp7 SPECIAL PUBLICATION NO. 12 B D N M M JI C H K P A-Water Canteen I-Shellac Brush B-Shellac Can J -Geological Hammer C- Field Book and Gummed Labels K- Hammer for Chiseling D- Chisels L- Whisk Broom E- Sheaf of Rice Paper M-Digger F- Prospecting Pick N-Duco Cement G- Cotton Batting O-Dust Brush H- Ball of Twine P-Awls(2 Curved,1 Straight) Wrapping Paper (Not shown) Figure 11. Fossil collector's field kit. FLORIDA GEOLOGICAL SURVEY grasping the opposite edge in one hand, pull the burlap tight, and with a sharp knife cut along the line of tension. The strips should be about five inches wide. For convenience in handling they should be cut at midlength, though a few complete strips should be saved for cross binding the block. 2. Plaster. The most satisfactory and easily obtained plaster for this work is No. 1 Moulding Plaster. It is moderately fast set- ting plaster but will allow ample time (20 to 30 minutes) for appli- cation to the block even when mixed in large quantities. Dental plaster sets too fast (and its cost is prohibitive) for use except in small quantities, and Gauging plaster (that which is normally used on walls) requires 24 hours to set. There is no rule of thumb for determining the quantity of plaster needed. The estimate must be based on experience, but it is better to mix too much than not enough. The following procedure in mixing has proven to be quite satisfactory in both the laboratory and field. Pour water equal to two-thirds of the volume of plaster needed into a pan (always add plaster to the water, never add water to the plaster), sift in plaster all over the surface of the water as long as the water will take it up. When a little dry plaster remains on the surface it is at the right consistency. Never stir the plaster until you are ready to use it. By doing so, you speed up the setting by about 10 minutes. If a second batch of plaster is needed, always wash the pan tho- roughly before mixing the second batch. Otherwise, when the first batch starts to set, it acts as a catalyst and the second batch sets immediately. (Most people have to learn this the hard way.) 3. Gum Arabic (Gum Acacia). This usually comes in crystal or granular form and should be mixed the evening before it is used so that it will have plenty of time to go into solution. Nor- mally it is mixed in the proportion of about / lb. of gum to a gallon of water. It can be applied to damp or wet specimens. This solution is an excellent culture medium for certain spores and will spoil in a week or so if a disinfectant is not added. Formaldehyde, phenol, or bichloride of mercury will prevent fer- mentation. If the bone and matrix are dry, a thin solution of white shellac in alcohol can also be used. 4. Pan. The most convenient vessel to use in mixing plaster is a plastic pan, either wash basin or dish pan. Plaster tends to stick to aluminum and galvanized iron, and vessels of these mater- ials are difficult to clean. Also, a pan is much more satisfactory SPECIAL PUBLICATION NO. 12 than a bucket for dipping the strips of burlap. 5. Knife. Even the best of knives may soon be dulled by the coarse fibers of the burlap bag. The type of knife which has pro- ven quite satisfactory is a butcher knife of fairly soft material which can be sharpened with a file. For stainless steel and the better grades of butcher knives, a carborundum stone is required and the edge does not last sufficiently longer to make it worth while. UNCOVERING THE SPECIMEN In uncovering the specimen, it is hardly necessary to say that one should work from the known to the unknown and that care must be exercised not to injure the bone. Most people have a tendency to remove too much matrix from the top of the specimen. Best results are obtained by removing only enough matrix to determine the limits of the specimen. Remember that nature, by means of rains and percolating ground water, has packed this specimen in matrix much better than you can ever hope to do. Above all, do not remove the matrix from beneath any bone because this will furnish an undercut, and when the protective plaster jacket is removed, the bone will be ripped out of the block. If the bone is very friable, as it is in most cases, it should be treated with the gum arabic or shellac solution. Do not brush the solution onto the bone, but dip the paint brush into the solu- tion and let it drain onto the area to be treated. Brushing the bone will disturb the small fragments. Use the gum arabic generously. For good preservation, the bone should be given all of the solution that it will absorb. If the bone is fragmented, it should be covered with paper. Facial tissues or soft toilet tissues are quite satis- factory. After the area to be covered has been thoroughly saturated with gum arabic or shellac. cover with 2 or 3 thicknesses of paper and pat the paper down onto the bone, using the ends of the bris- tles. Do not brush the paper. After the limits of the specimen have been determined, dig a shallow trench 3 or 4 inches deep around it at least 6 inches away from the specimen. Then saturate the bone and the matrix between the bones with the gum arabic or shellac solution. Except under extremely dry conditions, the block should be allowed to dry for 24 hours. If rain threatens, it should be covered with newspapers and a tarpaulin. FLORIDA GEOLOGICAL SURVEY PREPARING BLOCK FOR JACKETING After the block has become dry and firm, dig a trench around the specimen, keeping the inner wall about 6 inches from the specimen. The trench should be wide enough to stand in comfort- ably while working on the specimen. A "T" handled hay or steve- dore's hook is excellent for this task. The depth of the trench will vary somewhat with the thickness of the specimen and the nature of the matrix, but a convenient rule of thumb is to make the depth of the trench equal to at least half the width of the block. The block must be thick enough so that it will not break in turning. Next, with a trowel or other hand tool, the block should be trimmed to within 2 or 3 inches of the specimen. This margin protects the portions of the specimen near the edge of the block, both in turning the block and in transporting the specimen back to the laboratory. The sides of the block should be sloped in towards the center from top to bottom--otherwise, the block is apt to fall out of the jacket in turning. BE SURE TO UNDERCUT. The amount the block should be undercut depends on the size and thickness of the block. Usually 4 or 5 inches is sufficient. This last step is the key to whether or not the block can be safely held in the jacket while it is turned over. After the block has been trimmed and undercut, all exposed bone should be covered with 2 or 3 layers of the tissue paper in order to prevent the plaster from sticking to the bone. The proce- dure in papering, which is quite rapid and is least inconvenienced by normal winds, is to fold a short strip of toilet paper so that there are two or three thicknesses. Dip one side in water and apply the wet side to the bone. Pat into place with a dry brush using only the ends of the bristles. This molds the paper to the irregularities of the surface. The surface of the block should be checked for any places where the bone may have been undercut. If any are found, wad up some wet toilet or cleansing tissue and fill the undercuts. A mud mixture can also be used. Now the block is ready for jacket- ing. JACKETING THE BLOCK Presumably when the field worker has reached this stage he has equipped himself with moulding plaster, water, pan, burlap SPECIAL PUBLICATION NO. 12 strips and paper. A procedure in dipping the strips in plaster which is rapid and efficient, and requires a minimum of energy, is to take the end of a burlap strip in one hand and dip that end in the plaster. With the other hand hold the strip under the surface of the plaster while the strip is being drawn through the mixture. Remove the excess plaster from the burlap strip with the thumb and forefinger. If too much plaster is left on the strips, it makes the jacket too difficult to remove in the laboratory. Many paleontolo- gical specimens have been irreparably damaged in removing an overly thick jacket in the laboratory due to this type of thought- lessness on the part of the collector. It is for this reason that in a number of universities, the paleontologist in charge requires his graduate students to prepare the material they collect. Their memories seem to improve amazingly after they have become the victims of their own thoughtlessness. Never fold or wad the strips because this slows up the work. Apply the strip vertically to the side of the block so that it overlaps onto the top. Do not draw the strip tight but allow enough slack so that it will mold to the contours of the block. Mold the strip to the irregularities and depressions of the surface of the block with the ends of the fin- gers--not with the palm of the hand. Overlap the next strip for about half of its width onto this one and so on all the way around the block. Seal any gaps which occur on the top side of the block. Bind the long strips around the bottom of the vertical strips on the sides of the block, overlapping the ends of the long strips by 6 or 7 inches. If the block is large (5 feet square) apply a second coat to the top at right angles to the first. Allow the plaster plenty of time to set before disturbing the block. It will take at least an hour on a sunny day. Usually the small amount of stock feed mixed with the fibers of the sacks retards the setting o f the plaster somewhat. Most paleontologists use the thumbnail test to determine if the plaster has set suffi- ciently to turn the block. If the thumbnail barely makes an im- pression the block is ready to turn. The plaster gets noticeably warm on setting. This procedure works quite well for one, two or three people. A crew of three individuals who are used to working together is ideal because one can dip the strips as fast as two can apply them. If the block is large and reinforcing is needed, bind small poles (2 inches in diameter), boards or metal pipes to the top of the block with strips of burlap dipped in plaster, much as a doctor splints a broken limb. FLORIDA GEOLOGICAL SURVEY After the plaster is thoroughly set, the block is ready to turn over. Small blocks can be broken loose with the blow of a pick at the base of the supporting column at the bottom of the trench. With large blocks, it is often necessary to drive two or more stakes or bars horizontally under the block to loosen it. Trenches must be widened to accompany these bars. These are also handy levers in turning the block. Although different matrices have different weights, most of them are a little under or a little over 3,000 pounds per cubic yard. This will furnish a convenient figure for estimating the manpower necessary to roll the block over. Smaller blocks can be turned with a shovel. After the block has been turned the excess matrix should be removed, both for convenience in handling and for safety of the specimen in transportation. When bone has been encountered in one or two places it is better to stop. Remember, nature has already packed the specimen much better than you can hope to do. The removal of the excess matrix will leave much of the side walls on the jacket. The excess jacketing must be cut off and discarded. Do not fold down onto the block because it will not make good contact and the specimen may shift inside the jacket. It is not necessary to have the sides and bottom smooth. In fact, irregularities are highly desirable because they will prevent the specimen from shifting inside the jacket and becoming da- maged. Cover any exposed bone with toilet or cleansing tissue in the same manner in which the top side was covered. Now the block is ready to be sealed with plaster and burlap. Overlap the strips onto the top jacket 3 or 4 inches. If the block has dried over- night, as often happens, the old plaster must be thoroughly satu- rated with water in order to secure a good bond between the ol and new plaster. When the bottom seal sets, the specimen wil be encased in a hard shell which, if properly applied, fits the specimen tightly and the whole unit can stand rather severe jolt- ing. Make certain that the contents of the block are labeled on the set plaster jacket with an identifying field number that has been recorded in the field notes which describe the fossil find. The block can now be crated (if it is to be sent a consider- able distance) and forwarded tob a'laboratory or museum for further work. The plaster bandages can be-readily removed from one side by cutting with a saw or industrial tin shears when it is decided that the fossil is to be prepared -for study or display. A rather expensive, but ideal tool for this purpose is the cutter employed SPECIAL PUBLICATION NO. 12 27 by most hospitals for removing plaster casts from injured limbs. Small cartons of pre-packaged dry plaster bandages can also be obtained from hospital supply houses. These bandages are impregnated with the correct amount of dry plaster so that one need only add water and apply. They are ideal for small speci- mens. SFLORIDA GEOLOGICAL SURVEY REFERENCES Camp, C.L. 1937 (and Hanna, G.D.) Methods in paleontology: Univ. of Califor- nia Press, Berkeley, 153 p. Cornwall, I.W. 1956 Bones for the archaeologist: Macmillan Co., New York. Grossman, J.D. (See Sisson, S.) Hanna, G.D. (See Camp, C.L.) Olsen, S.J. 1959 Fossil mammals of Florida: Florida Geol. Survey, Spec. Pub. no. 6. 75 p. 1961 A list, bibliography and index to facilitate the identification of vertebrate remains from archaeological sites: Texas Archae. Society, Bull., vol. 30, (for 1959), p. 219-222. 1964 Mammal remains from archaeological sites, part I, southeastern and southwestern United States: Papers of the Peabody Museum of Archaeology and Ethology, Harvard Univ., Vol. LVI, no. 1. 162 p. Purl, H.S. 1964 (and Vernon, R.O.) Summary of the geology of Florida and a guidebook to the classic exposures: Florida Geol. Survey Spec. Pub. no. 5. 312 p. Ray, C. 1957 A list, bibliography, and index of the fossil vertebrates of Florida: Florida Geol. Survey, Spec. Pub. no. 3. 175 p. Romer, A.S. 1955 Vertebrate paleontology: Univ. of Chicago Press, Chicago. 687 p. Sisson, S. 1953 (and Grossman, J.D.) The anatomy of the domestic animals: W.B. Saunders Co., Philadelphia. 4th edition. 972 p. Vernon, R.O. (See PuHi, H.S.) OL "Q |
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