First Record of the Anuran Family Rhinophrynidae from the Oligocene of Eastern North America
The anuran family Rhinophrynidae today comprises a single species restricted to southernmost Texas and Central America. Three extinct genera allied to this family are known from the Jurassic (Rhadinosteus) and Eocene (Chelomophrynus, Eorhinophrynus), whereas the sole extant genus Rhinophrynus is known from the latest Eocene (Chadronian) of Saskatchewan and the Pleistocene of Mexico. We provide the first records of the Rhinophrynidae from the Oligocene of eastern North America. From two of the oldest terrestrial vertebrate sites on the Florida peninsula (I-75, early Oligocene; Brooksville 2, late Oligocene), we have identified one nearly complete and several partial humeri, two radioulnae, two partial presacral vertebrae, three partial ilia, and one femur that are all referable to the Rhinophrynidae. These specimens are similar in size to the Eocene Rhinophrynus canadensis, smaller than the extant R. dorsalis, and might be distinguishable from both by features of the ilium and humerus. The presence of rhinophrynids during the Oligocene provides the first indication of change in the anuran fauna on the Florida peninsula during the Cenozoic.Abstract
Osteological comparisons between Rhinophrynus dorsalis and fossil Rhinophrynus sp. from the Oligocene of Florida. In the center, skeleton of R. dorsalis (UF-Herp-13375-4) highlighting elements recovered in the fossil record. Surrounding the skeleton, each element from this recent specimen is to the right of the fossils: (a) right humerus (UF-VP-16714), anterior view; (b) presacral vertebra (UF-VP-431018 compared to presacral V), anterior view; (c) left femur (UF-VP-446627), posterior view; (d) right radioulna (UF-VP-446628), anterior view; (e) presacral vertebra (UF-VP-431019 compared to presacral VIII), anterior view; and (f) right ilium (UF-VP-431014), lateral view. Abbreviations: dae, dorsal acetabular expansion; dc, distal condyle; dp, dorsal protuberance; lc, lateral crest; na, neural arch; ue, ulnar epicondyle; vae, ventral acetabular expansion; vc, ventral crest; vs, ventral sulcus. Scale bars = 2.00 mm.
Osteological comparison of anuran genera native today to the southeastern United States and frequently recovered in the fossil record of Florida. (a) Right humerus (anterior view), (b) right radioulna (anterior view), (c) right ilium (lateral view), and (d) left femur (posterior view). Species samples include Acris gryllus (UF-Herp-107362), Anaxyrus terrestris (UF-Herp-3170), Gastrophryne carolinensis (UF-Herp-110645), Rana clamitans (UF-Herp-76511), Scaphiopus holbrookii (UF-Herp-9620), and Rhinophrynus dorsalis (UF-Herp-13375-4). Scale bars = 2.00 mm.
Contributor Notes
