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Vertebrate Paleontology

Fossil Species of Florida

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Amphibia, Lissamphibia, Salientia, Anura, Bufonidae


Common Name: Inglis toad

Alternate Scientific Name: Anaxyrus defensor

Source of Species Name: Bufo defensor is named for a conservation group, the Florida Defenders of the Environment. The type locality of Bufo defensor was discovered during excavations for the Cross Florida Barge Canal, but the completion of the canal was later halted through efforts by the Florida Defenders of the Environment to prevent it from cutting into the Floridan Aquifer (Meylan, 2005).

Age Range: early Pleistocene (latest Blancan), about 2.1 to 1.6 million years ago.

Florida Fossil Occurrences:

Florida map with occurrences indicated

Figure 1. Map of Florida, with black circles indicating counties where fossils of Bufo defensor have been found (the circles do not indicate a specific location within the county where the fossils were found, and some counties may have two or more different locations producing this species).

Florida Fossil Sites with Bufo defensor:
Citrus County—Inglis 1A
Marion County—Withlacochee River 1A

Overall Geographic Range: Bufo defensor has only been recovered from central Florida. The type locality is Inglis 1A, a sinkhole that formed within the Eocene Inglis Formation, in Citrus County, Florida.

Comments: Bufo defensor has only been recovered from two fossil localities, both from the early Pleistocene of the Florida peninsula. The type locality, Inglis 1A, was uncovered in 1967 during excavations for the Cross Florida Barge Canal and is interpreted to be a sinkhole within the Eocene Inglis Formation. Using biostratigraphy, the site was dated to latest Blancan based on the presence of several mammalian species that are restricted to late Blancan faunas (Klein, 1971; Hulbert, 2010). In 1974, a crew from the Florida Museum of Natural History screen-washed sediment from the Inglis 1A site and found may fossil anurans, along with other microfauna (Meylan, 2005). This site is particularly important for understanding the evolutionary history of anurans because it fills in a 7 million year gap between the early Miocene and late Pleistocene faunas from which fossil anurans were previously known (Meylan, 2005). Six frog taxa were recovered from Inglis 1A, which Meylan (2005) stated was an “essentially modern anuran fauna”, as five species were modern and Bufo defensor was the only extinct taxon. Meylan (2005) interpreted the sinkhole to be surrounded by a xeric, or dry, habitat based upon known adaptations in most of the frog species.

Bufo defensor was first listed as Bufo n. sp. in Hulbert (2001) before being formally described by Meylan in 2005. Meylan (2005) placed his new toad species in the genus Bufo. Some subsequent molecular studies (e.g., Frost et al., 2006; Pyron and Wiens, 2011) determined that Bufo was a paraphyletic clade, and that North American species formerly placed in that genus should instead be included in the genus Anaxyrus. Other studies by modern herpetologists favor retention of the North American toads in Bufo (e.g., Pauly et al., 2009). Given this uncertainty in how to resolve this issue among the living toads, traditional taxonomy is maintained here for now. Martín et al. (2012) formally proposed that Bufo defensor be reassigned to Anaxyrus , but without any examination of the fossils themselves.

Skull of Amphicyon longiramus

Figure 2. UF 222916, holotype of Bufo defensor from Inglis 1A, Citrus County. Right frontoparietal in dorsal view, anterior is towards the top of the page. Note the large supraorbital crest on the lateral (right) side, and the slightly concavity on the medial (left) side.

canine teeth of Amphicyon

Figure 3. UF 222916, holotype of Bufo defensor. Right frontoparietal in posterior view. Note the large hemisphere formed by the supraorbital crest.

The holotype of Bufo defensor is a right frontoparietal (UF 222916), which is part of the top of the skull (Figs. 2-3). This element was chosen as the holotype because it has been proposed by Tihen (1962) to be the most useful for differentiating New World bufonids (Meylan, 2005). Bufo defensor is differentiated from all other members of its genus by the unusually large supraorbital crest on the frontoparietal, which becomes a large spherical protuberance posteriorly (Meylan, 2005). Meylan (2005) noted that Bufo defensor looks most similar to the modern Bufo terrestris (=Anaxyrus terrestris of Frost et al., 2006), but the larger supraorbital crest, as well as the overall larger size of Bufo defensor, differentiates the two species. The frontoparietals of the two species are similar in shape, in which the supraorbital crests increase in height posteriorly and end in a ball-like structure and the medial side of the frontoparietal is slightly concave. The ilia of Bufo defensor and Bufo terrestris are also similar in having a low ilial prominence with an anterior slope that ranges from much steeper than to subequal to the posterior slope. The ilium in Figure 4 shows a near subequal state between the anterior and posterior slopes of the ilial prominence.

femur of Amphicyon

Figure 4. UF 222915, right ilium of Bufo defensor from Inglis 1A in lateral view, anterior to the right.

astragalus of Amphicyon

Figure 5. UF 223011, right scapula of Bufo defensor from Inglis 1A in ventral view.

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Scientific Publications and Other References Cited:

Frost, D. R., T. Grant, J. Faivovich, R. H. Bain, A. Haas, C. F. Haddad, R. O. De Sá, A. Channing, M. Wilkinson, S. C. Donnellan, C. J. Raxworthy, J. A. Campbell, B. L. Blotto, P. Moler, R. C. Drewes, R. A. Nussbaum, J. D. Lynch, D. M. Green, & W. C. Wheeler. 2006. The Amphibian Tree of Life. Bulletin of the American Museum of Natural History, 297:1-370. http://dx.doi.org/10.1206/0003-0090(2006)297[0001:TATOL]2.0.CO;2

Hulbert Jr., R. C. 2001. Checklist of Florida’s fossil vertebrates. Pp. 34-74 in R. C. Hulbert (ed.), The Fossil Vertebrates of Florida. University Press of Florida, Gainesville. http://www.flmnh.ufl.edu/vertpaleo/book.htm

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. http://www.flmnh.ufl.edu/bulletin/vol49no3/vol49no3.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.

Martín, C., M. A. Alonso-Zarazaga, & B. Sanchiz. 2012. Nomenclatural notes on living and fossil amphibians. Graellsia, 68(1): 159-180. doi:10.3989/graellsia.2012.v68.056

Meylan, P. 2005. Late Pliocene anurans from Inglis 1A, Citrus County, Florida. Bulletin of the Florida Museum of Natural History 45(4):171–178. http://www.flmnh.ufl.edu/bulletin/Meylanlowres.pdf

Pauly, G. B., D. M. Hillis, and D. C. Cannatella. 2009. Taxonomic freedom and the role of official lists of species names. Herpetologica, 65(2):115–128. http://www.lifesci.utexas.edu/faculty/antisense/papers/Paulyetal2009.pdf

Pyron, R. A., and J. J. Wiens. 2011. A large-scale phylogeny of Amphibia including over 2800 species, and a revised classification of extant frogs, salamanders, and caecilians. Molecular Phylogenetics and Evolution, 61(2): 543-583. http://dx.doi.org/10.1016/j.ympev.2011.06.012

Tihen, J. A. 1962. A review of New World fossil bufonids. American Midland Naturalist, 68(1):1-50. http://www.jstor.org/stable/2422634

Original Author(s): Carly L. Manz

Original Completion Date: December 6, 2012

Editor(s) Name(s): Richard C. Hulbert Jr.

Last Up-dated On: March 31, 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.

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