University of Florida Vertebrate Fossil Locality CI001
Inglis 1A is located about 1.5 miles (2.5 km) south of the town of Inglis, on the north bank of the Cross Florida Barge Canal west of US Highway 98, Citrus County, Florida. 29.01º N; 82.69º W.
- Early Pleistocene Epoch; latest Blancan land mammal age
- 1.9-1.6 million years ago
Basis of Age
An early Pleistocene, late Blancan age is confirmed by the presence of the sloth Megalonyx leptostomus, the hyena Chasmaporthetes ossifragus, the mustelid Trigonictis macrodon, the peccary Platygonus bicalcaratus, the pronghorn Capromeryx arizonensis, the muskrat Ondatra idahoensis, and many others. Inglis 1A falls within the latest part of the late Blancan based on the co-occurrence of Sigmodon curtisi, Peromyscus sarmocophinus, and Spilogale putorius (Hulbert, 2010). The mammalian fauna is generally regarded as a close correlate of that from Curtis Ranch in Arizona, whose age is well established by magnetostratigraphy and radioisotopic geochronology.
Inglis 1A consisted from bottom to top of a basal conglomerate unit, thin bed of clay, lower sand unit, a second thin clay bed, upper sand unit, and a cemented quartz sandstone (Klein, 1971). The entire sequence varied from 3 to 4 m thick, with the two sands comprising the majority of the deposit. The two sand units also produced the majority of the fossils. The bottom of the deposit is slight below modern sea level. As no marine species were found in the deposit (except those clearly reworked from the surrounding limestone walls of the sinkhole), deposition occurred at a time when the area was inland from the coast. As this part of Florida has been uplifted by about 80 meters in the last 1.7 million years (Adams et al., 2010), global sea level was over 80 meters (260 feet) lower than it is now when the Inglis 1A sinkhole formed, placing it within a glacial period.
The site was originally a sinkhole with an opening of about 10 × 20 m. The habitat surrounding the sinkhole at the time of deposition included longleaf pine flatwoods and pine-oak scrub based on ecological interpretation of the snakes, lizards, and birds (Meylan, 1982; Emslie, 1998). Cooler summer temperatures than today is indicated by the presence of spruce pollen in the sediments (Emslie, 1998), although abundant large tortoises and armadillos imply that winters were not significantly colder than today.
Inglis 1A was a very rich deposit, producing about 18,000 identifiable fossils representing at least 161 species. The total is the second highest for any single fossil site in the state of Florida, trailing only Leisey Shell Pit 1A. All four main terrestrial vertebrate groups, amphibians, reptiles, birds, and mammals, are abundant, and both small and large species are present. All recovered fossils were isolated finds; there were no associated or articulated skeletons. Freshwater aquatic and semiaquatic species are relatively uncommon compared to purely terrestrial species, and marine species are absent.
(†= extinct species; *=species no longer living in Florida)
Bony Fish (Osteichthyes)
unidentified vertebra and spines
†Hesperotestudo (Caudochelys) n. sp.
†Hesperotestudo (Hesperotestudo) sp.
Anas crecca or Anas discors
Rallus sp. cf. R. longirostris
cf. Gymnogyps sp.
†Glaucidium n. sp.
Picoides sp. cf. P. villosus
cf. Hylocichla mustelina
Zonotrichia sp. cf. Z. leucophrys
Vermivora sp. cf. V. celata
Junco sp. cf. J. hyemalis
†Glaucomys n. sp.
Peromyscus sp. cf. P. polionotus
Lynx sp. cf. †L. rexroadensis
Lynx sp. cf. L. rufus
Excavation History and Methods
The south wall of the sediment-filled sinkhole called Inglis 1A was removed during the excavation in the mid-1960s of the western portion of the Cross Florida Barge Canal. This massive federal project was to allow commercial barge traffic between the Atlantic and Gulf coasts of Florida (Noll and Tegeder, 2009). This project was eventually stopped over environmental objections, but not before the western stretch of the canal, from Lake Rousseau to the Gulf of Mexico, was completed. Fossils were discovered eroding out the remaining sediment in the sinkhole by UF paleontology graduate students Jean Klein and Robert Martin in 1967. Sporadic, small-scale collecting by FLMNH crews occurred at the site from 1967 to 1973. A major excavation lead by museum curator David Webb began in December 1973 and lasted through March 1974, with approximately 2000 person-hours invested in the work (S. D. Webb field notebook). Approximately 300 cubic meters of the fossiliferous sand layers were excavated; most of this was screenwashed on-site while the remainder was taken to the museum on the UF campus where it could be washed through screens with smaller openings. At the end of this excavation, almost all of the fossil-bearing sediments filling the sinkhole had been removed. Over the next two decades a relatively small number of specimens were found by amateur collectors, some of which were later donated to the museum. A crew comprised of students from Western State College lead by Dr. Steven Emslie and Steve and Suzan Hutchens collected the last major accumulation of fossils from Inglis 1A in April 1996, although most of their efforts were focused on the nearby Inglis 1C locality.
Inglis 1A certainly ranks in the top 10 Florida vertebrate fossils sites as ranked by scientific significance. This is based on more than just its incredibly rich fauna and large samples of many species. Eleven new species were described on the basis of specimens from Inglis 1A: the toad Bufo defensor; the skink Plestiodon carri, the snake Regina intermedia; the eagle Aquila bivia; the owl Glaucidium explorator; the rabbit Sylvilagus webbi; the pocket gopher Orthogeomys propinetis; the porcupine Erethizon kleini; the fox Urocyon citrinus; the raccoon Procyon megalokolos, and the canid Theriodictis? floridanus. As noted in the reviews of the site’s snakes and lizards by Meylan (1982) and birds by Emslie (1998), Inglis 1A provides the oldest known records of many of today’s common native Florida animals. The large number of species that dispersed from South America found in the Inglis 1A local fauna started David Webb’s interest in the Great American Biotic Interchange, a topic upon which he wrote many significant papers during his long career (e.g., Webb, 1976; Marshall et al., 1982; Webb, 1991; Webb, 2006). Specimens from Inglis 1A formed a major component if not the primarily study material for theses and dissertations of several generations of graduate students both at the University of Florida and elsewhere. Published versions of these include Steadman (1980), Frazier (1981), Meylan (1982), Wilkins (1984), Meachen (2005), and Emmert and Short (2018). Specimens from Inglis 1A have recently been extensively used in analyses of stable isotopes of carbon and oxygen from tooth enamel to determine ancient climates and diets (DeSantis et al., 2009; Yann et al., 2013; Yann and DeSantis, 2014; Feranec and DeSantis, 2014).
It is worth noting most references written before 2005 (and a few afterwards) gave the age of Inglis 1A as early Irvingtonian and not latest Blancan as stated above. This does not mean that the relative age of the site has changed. Instead, in 2005, Bell et al. revised the boundary between the Blancan and Irvingtonian land mammal ages, moving it from about 2 million years ago to about 1.6 million years ago. Thus, sites in that interval were transferred from the Irvingtonian land mammal age to the Blancan land mammal age, although their geologic age remained the same.
- Original Author: Richard C. Hulbert Jr.
- Original Completion Date: April 3, 2015
- Editor(s) Name(s): Natali Valdes
- Last Updated: February 17, 2022
Adams, P. N., N. D. Opdyke, and J. M. Jaeger. 2010. Isostatic uplift driven by karstification and sea-level oscillation: Modeling landscape evolution in north Florida. Geology 38(6):531-534.
Bell, C. J., E. L. Lundelius Jr, A. D. Barnosky, R. W.Graham, E. H. Lindsay, D. R. Ruez Jr., H. A. Semken Jr., S. D. Webb, and R. J. Zakrzewski. 2004. The Blancan, Irvingtonian, and Rancholabrean mammal ages. Pp. 232–314 in M. O. Woodburne (ed.), Late Cretaceous and Cenozoic Mammals of North America. Columbia University Press New York.
DeSantis, L. R. G., R. S. Feranec, and B. J. MacFadden. 2009. Effects of global warming on ancient mammalian communities and their environments. PLoS ONE 4(6):e5750. doi:10.1371/journal.pone.0005750pone.0005750.
Emmert, L. G., and R. A. Short. 2018. Three new procyonids (Mammalia, Carnivora) from the Blancan of Florida. Bulletin of the Florida Museum of Natural History 55(8):157–173.
Emslie, S. D. 1995. The fossil record of Arctodus pristinus (Ursidae: Tremarctinae) in Florida. Bulletin of the Florida Museum of Natural History 37:501-514.
Emslie, S. D. 1998. Avian community, climate, and sea-level changes in the Plio-Pleistocene of the Florida Peninsula. Ornithological Monographs, No. 50, 113 p.
Emslie, S. D., and N. J. Czaplewski. 1999. Two new fossil eagles from the late Pliocene (late Blancan) of Florida and Arizona and their biogeographic implications. Smithsonian Contributions to Paleobiology 89.
Feranec, R. S., and L. R. G. DeSantis. 2014. Understanding specifics in generalist diets of carnivorans by analyzing stable carbon isotope values in Pleistocene mammals of Florida. Paleobiology 40(3):477-493.
Frazier, M. K. 1982. A revision of the fossil Erethizontidae of North America. Bulletin of the Florida State Museum 27:1-76.
Hulbert Jr., R. C. 2010. A new early Pleistocene tapir (Mammalia: Perissodactyla) from Florida, with a review of Blancan tapirs from the state. Bulletin of the Florida Museum of Natural History 49(3):67-126. (Download PDF)
Klein, J. G. 1971. The ferungulates of the Inglis 1A local fauna, early Pleistocene of Florida. M.Sc. Thesis, University of Florida, Gainesville, 115 p.
Marshall, L. G., S. D. Webb, J. J. Sepkoski, and D. M. Raup. 1982. Mammalian evolution and the Great American Interchange. Science 215:1351-1357.
Meachen, J. A. 2005. A new species of Hemiauchenia (Artiodactyla, Camelidae) from the late Blancan of Florida. Bulletin of the Florida Museum of Natural History 45(4):435-447. (Download PDF)
Meylan, P. A. 1982. The squamate reptiles of the Inglis 1A fauna (Irvingtonian: Citrus County, Florida). Bulletin of the Florida State Museum 27:1-85.
Meylan, P. 2005. Late Pliocene anurans from Inglis 1A, Citrus County, Florida. Bulletin of the Florida Museum of Natural History 45(4):171-178.
Morgan, G. S., and R. C. Hulbert, Jr. 1995. Overview of the geology and vertebrate biochronology of the Leisey Shell Pit local fauna, Hillsborough County, Florida. Bulletin of the Florida Museum of Natural History 37:1-92.
Noll, Steven, and David Tegeder. 2009. Ditch of Dreams: The Cross Florida Barge Canal and the Struggle for Florida’s Future. University Press of Florida, Gainesville, 352 p.
Steadman, D. W. 1980. A review of the osteology and paleontology of turkeys (Aves: Meleagrinae). Natural History Museum of Los Angeles County Contributions in Science 330:131-207.
Stidham, T. A. 2011. The carpometacarpus of the Pliocene turkey Meleagris leopoldi (Galliformes: Phasianidae) and the problem of morphological variability in turkeys. PaleoBios 30(1):1-17.
Tedford, R. H., X. Wang, and B. E. Taylor. 2009. Phylogenetic systematics of the North American fossil Caninae (Carnivora: Canidae). Bulletin of the American Museum of Natural History 325:1-218.
Webb, S. D. 1974. Chronology of Florida Pleistocene mammals. Pp. 5-31 in S. D. Webb (ed.), Pleistocene Mammals of Florida. University of Florida Press, Gainesville.
Webb, S. D. 1976. Mammalian faunal dynamics of the Great American Interchange. Paleobiology 2(3):220-234.
Webb, S. D. 1991. Ecogeography and the Great American Interchange. Paleobiology 17(3):266–280.
Webb, S. D. 2006. The Great American Biotic Interchange: patterns and processes. Annals of the Missouri Botanical Garden 93(2):245-257.
Wilkins, K. T. 1984. Evolutionary trends in Florida Pleistocene pocket gophers (genus Geomys), with description of a new species. Journal of Vertebrate Paleontology 3:166-181.
Yann, L. T., and L. R. G. DeSantis. 2014. Effects of Pleistocene climates on local environments and dietary behavior of mammals in Florida. Palaeogeography, Palaeoclimatology, Palaeoecology 414:370-381.
Yann, L. T., L. R. G. DeSantis , R. J. Haupt , J. L. Romer , S. E. Corapi and D. J. Ettenson. 2013. The application of an oxygen isotope aridity index to terrestrial paleoenvironmental reconstructions in Pleistocene North America. Paleobiology 39(4):576-590.
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.