University of Florida Vertebrate Fossil Locality GI001
Location: About 8 miles north-northeast of Bell, Gilchrist County, Florida; 29.9° N, 82.8° W.
Age: early Miocene Epoch; Hemingfordian Land Mammal Age. About 18 million years old (estimated).
Basis of Age: biochronology (an early Hemingfordian age is indicated by the combined presence of the bear Phoberocyon, the mustelid Leptarctus, the rhino Floridaceras, and the canid Metatomarctus).
Geology: fossils are found in alternating beds of clay and calcareous sand, with occasional lenses or beds of limestone boulders.
Depositional Environment: ancient sinkhole with an associated cave system
Excavation History and Methods: The site was discovered by Clarence Simpson of the Florida Geological Survey in 1931, who found fossils on the spoil pile of a well dug by Raeford Thomas. Florida Geological Survey crews excavated at the site until January 1932. The recovered specimens were sent to George G. Simpson, then of the American Museum of Natural History, who recognized their significance and quickly published the first scientific paper on the site in 1932. Thomas Barbour of Harvard University purchased the site and the surrounding 40 acres in the late 1930s and deeded it to the University of Florida, with the provision that field crews from Harvard?s Museum of Comparative Zoology could collect at the fossil site. Museum of Comparative Zoology field crews led by Ted White conducted the first large scale excavations at Thomas Farm, and these continued until the early 1950s. Then the site was worked cooperatively until about 1960 by the University of Florida (by Walter Auffenberg, Pierce Brodkorb, and Robert Bader of the Department of Biology; specimens curated in the Florida Museum of Natural History collection) and the Florida Geological Survey (led by the newly hired Stanley Olsen, who had previously worked at the site for Harvard). Auffenberg and Brodkorb were the first to intensively use screenwashing at this site, which proved to have a remarkably rich small vertebrate fauna. Between 1960 and 1980, the site was worked infrequently by the Florida Museum of Natural History, as other major Florida fossil sites, such as Inglis 1A, Love Bone Bed, McGehee Farm, Withlacoochee River 4A, and others were discovered and worked by museum crews.
The next major phase of excavation began in 1981, with field work led by then UF graduate student Ann Pratt. Pratt and co-workers established a permanent grid system and were the first to measure detailed locations and orientations for bones in the site (Pratt, 1990). Many tons of sediment from the site were screenwashed to recover small vertebrate fossils, and screens with smaller size mesh than before were used, resulting in recovery of even smaller specimens. Field work at Thomas Farm has continued through the present, with at least one field season per year. David Steadman of the Florida Museum of Natural History is the person currently in charge of collecting at Thomas Farm. Despite over 75 years of excavations and recovery of tens of thousands of fossils, a large volume of sediment remains to be dug. Current excavation practice is to work in 1 meter by 1 meter areas (within the grid system established in 1981) and at depth intervals of 10 centimeters. All matrix is saved and wet screened, either on site, or at the FLMNH.
New species continue to be found and described from Thomas Farm on a regular basis (e.g., Morgan and Czaplewski, 2003; Labs Hochstein, 2007; Steadman, 2008; Beatty, 2010). Discovery and excavation of important specimens of rare taxa also occur frequently. For example, relatively complete skulls of Amphicyon longiramus and Alligator olseni were found during the Fall 2009 dig. To see a videos from recent (2010 and 2012) digs at Thomas Farm, follow these links the museum's YouTube channel: http://www.youtube.com/watch?v=EFiqIKdkWQw  and http://www.youtube.com/watch?v=SjXPGHccTxI&list=UUv0fbbG8Lqnuk-lnziLDZ1Q&index=47 .
Comments: By almost any measure, Thomas Farm is the single most important vertebrate fossil site in Florida, and a good case could be made that it is the most important vertebrate fossil site of Cenozoic age from the eastern United States. At the time of its discovery, very little was known of early Miocene terrestrial faunas in eastern North America. Thomas Farm has extremely large samples of both small and large vertebrates, including types of animals that are often rare elsewhere, such as birds, carnivores, and bats. Except for fish, all other types of vertebrates are well represented. Many dozens of new species have been named based on specimens from Thomas Farm. Thomas Farm and the surrounding property is owned by the University of Florida and no access or digging is allowed except as part of organized excavations lead by Florida Museum paleontologists.
[Note that there is an extensive scientific literature that discusses specimens from Thomas Farm. This list, long as it is, is not comprehensive, but is rather intended to demonstrate both the long duration of scientific interest in the fossils from this site and the breadth of taxonomic diversity covered by that literature.]
Auffenberg, W. 1963. The fossil snakes of Florida. Tulane Studies in Zoology and Botany 10:131-216.
Bader, R. S. 1956. A quantitative study of the Equidae of the Thomas Farm Miocene. Bulletin Museum of Comparative Zoology, 115(2):49-78.
Beatty, B. L. 2010. A new aletomerycine (Artiodactyla, Palaeomerycidae) from the early Miocene of Florida. Journal of Vertebrate Paleontology 84(2):613-617.
Becker, J. J. 1986. Reidentification of ?Phalacrocorax? subvolans Brodkorb as the earliest record of the Anhingidae. The Auk 103:804-808.
Becker, J. J., and P. Brodkorb. 1992. An early Miocene ground-dove (Aves: Columbidae) from Florida. Natural History Museum of Los Angeles County Science Series 36:189-193.
Bhullar, B.-A. S., and K. T. Smith. 2008. Helodermatid lizard from the Miocene of Florida, the evolution of the dentary in Helodermatidae, and comments on dentary morphology in Varanoidea. Journal of Herpetology 42(2):286?302.
Black, C. C. 1963. Miocene rodents from the Thomas Farm local fauna, Florida. Bulletin of the Museum of Comparative Zoology 128:483-501.
Brodkorb, P. 1956. Two new birds from the Miocene of Florida. Condor, 58(5):367-370.
Bryant, J. D. 1991. Age-frequency profiles of micromammals and population dynamics of Proheteromys floridanus (Rodentia) from the early Miocene Thomas Farm site, Florida. Palaeogeography, Palaeoclimatology, Palaeoecology 85(1-2):1-14.
Czaplewski, N. J., and G. S. Morgan. 2000. A new vespertilionid bat (Mammalia: Chiroptera) from the early Miocene (Hemingfordian) of Florida, USA. Journal of Vertebrate Paleontology 20(4):736-742.
Estes, R. 1963. Early Miocene salamanders and lizards from Florida. Quarterly Journal of the Florida Academy of Sciences 26:234-256.
Goin, C. J., and W. Auffenberg. 1955. The fossil salamanders of the family Sirenidae. Bulletin of the Museum of Comparative Zoology, 113:495-514.
Holman, J. A. 1961. A new hylid genus from the lower Miocene of Florida. Copeia 1961:354-355.
Holman, J. A. 1965. Early Miocene anurans from Florida. Quarterly Journal of the Florida Academy of Sciences 28(1):76-77.
Hulbert, R.C. 1984. Paleoecology and population dynamics of the early Miocene (Hemingfordian) horse Parahippus leonensis from the Thomas Farm site, Florida. Journal of Vertebrate Paleontology 4:547-558.
Hulbert, R. C., and B. J. MacFadden. 1991. Morphologic transformation and cladogenesis at the base of the radiation of hypsodont horses. American Museum Novitates. Number 3000:1-61.
Labs Hochstein, J. 2007. A new species of Zodiolestes (Mammalia, Mustelidae) from the early Miocene of Florida. Journal of Vertebrate Paleontology 27(2):532-534.
MacFadden, B. J. 2001. Three-toed browsing horse Anchitherium clarencei from the early Miocene (Hemingfordian) Thomas Farm, Florida. Bulletin of the Florida Museum of Natural History 43(3):79-109.
Morgan, G. S., and N. J. Czaplewski. 2003. A new bat (Chiroptera: Natalidae) from the early Miocene of Florida, with comments on natalid phylogeny. Journal of Mammalogy 84(2):729-752.
Olsen, S. J. 1956. The Caninae of the Thomas Farm Miocene. Breviora, 66:1-12.
Olsen, S. J. 1957. Leptarctines from the Florida Miocene (Carnivora, Mustelidae). American Museum Novitates, 1861:1-7.
Olsen, S. J. 1958. The fossil carnivore Amphicyon intermedius from the Thomas Farm Miocene. Part I?skull and dentition. Bulletin of the Museum of Comparative Zoology 118(4):157-172.
Olsen, S. J. 1958. Some problematic carnivores from the Florida Miocene. Journal of Paleontology 32(3):595-602.
Olsen, S. J. 1960. The fossil carnivore Amphicyon longiramus from the Thomas Farm Miocene. Part II?postcranial skeleton. Bulletin of the Museum of Comparative Zoology 123(1):1-44.
Olsen, S. J. 1962. The Thomas Farm fossil quarry. Quarterly Journal of the Florida Academy of Sciences, 25(2):142-146.
O?Sullivan, J. A. 2005. Population dynamics of Archaeohippus blackbergi (Mammalia; Equidae) from the Miocene Thomas Farm fossil site of Florida. Bulletin of the Florida Museum of Natural History 45(4):449-463.
Patton, T. H. 1967. Revision of the selonodont artiodactyls from Thomas Farm. Quarterly Journal of the Florida Academy of Sciences, 29:179-190.
Pratt, A. E. 1989. Taphonomy of the microvertebrate fauna from the early Miocene Thomas Farm locality, Florida (U.S.A.). Palaeogeography, Palaeoclimatology, Palaeoecology 76(1/2):125-151.
Pratt, A. E., and G. S. Morgan. 1989. New Sciuridae (Mammalia: Rodentia) from the early Miocene Thomas Farm local fauna, Florida. Journal of Vertebrate Paleontology 9:89-100.
Pratt, A. E. 1990. Taphonomy of the large vertebrate fauna from the Thomas Farm locality (Miocene, Hemingfordian), Gilchrist County, Florida. Bulletin of the Florida Museum of Natural History 35(2):35-130.
Simpson, G.G. 1932. Miocene land mammals from Florida. Bulletin of the Florida Geological Survey 10:11-41.
Snyder, D. 2007. Morphology and systematics of two Miocene alligators from Florida, with a discussion of Alligator biogeography. Journal of Paleontology 81(5):917-928.
Steadman, D. W. 2008. Doves (Columbidae) and cuckoos (Cuculidae) from the early Miocene of Florida. Bulletin of the Florida Museum of Natural History 47(2):49-72.
Tedford, R. H., and C. D. Frailey. 1976. Review of some Carnivora (Mammalia) from the Thomas Farm Local Fauna (Hemingfordian, Gilchrist County, Florida). American Museum Novitates 2610:1?9.
Tihen, J. A. 1951. Anuran remains from the Miocene of Florida, with the description of a new species of Bufo. Copeia 1951(3):230-235.
Wang, X., R. H. Tedford, and B. E. Taylor. 1999. Phylogenetic systematics of the Borophaginae (Carnivora: Canidae). Bulletin of the American Museum of Natural History 243:1-391.
Wetmore, A. 1943. Fossil birds from the Tertiary deposits of Florida. Proceedings of the New England Zoological Club 22:59-68.
White, T. E. 1942 A new alligator from the Miocene of Florida. Copeia 1942(1):3-7.
White, T. E. 1942. The Lower Miocene mammal fauna of Florida. Bulletin of the Museum of Comparative Zoology 92(1):1-49.
Williams, E. E. 1953. A new fossil tortoise from the Thomas Farm Miocene of Florida. Bulletin of the Museum of Comparative Zoology 107(11):537-552.
Wood, H. E. 1964. Rhinoceroses from the Thomas Farm Miocene of Florida. Bulletin of the Museum of Comparative Zoology, 130:361-386.
Faunal List (=extinct species; *=species no longer living in Florida)
Clupeidae, genus and species indeterminate
Scaphiopus cf. holbrooki
Gastrophryne cf. carolinensis
cf. Gopherus sp.
cf. Anolis sp.
Scincidae, genus and species indeterminate
Teiidae, genus and species indeterminate
Anguidae, genus and species indeterminate
Anseriformes, genus and species indeterminate
Ardeidae, genus and species indeterminate
Plegadis n. sp.
Coraciidae, genus and species indeterminate
Cuculidae, genus and species indeterminate
Rallidae, genus and species indeterminate
Emberizidae, genus and species indeterminate
Capitonidae, genus and species indeterminate
Strigiformes, genus and species indeterminate
cf. Stenogale sp.
cf. Miomustela sp.
Procyonidae, genus and species indeterminate
Emballonuridae, genus and species indeterminate
Molossidae, genus and species indeterminate
Mormoopidae, genus and species indeterminate
Eomyidae, genus and species indeterminate
Muridae, genus and species indeterminate
Author: Richard C. Hulbert Jr.; Original Date: January 30, 2009
Last Edited by: Richard C. Hulbert Jr.; Last up-dated On: March 28, 2013
This material is based upon work supported by the National Science Foundation under Grant Number CSBR 1203222, Jonathan Bloch, Principal Investigator. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.