The Squamate Reptiles of the Inglis IA Fauna (Irvingtonian: Citrus County, Florida)

Abstract

The early Pleistocene, Inglis IA site has yielded the largest and most diverse sample of fossil squamates in eastern North America. About 4000 specimens, including 250 skull elements, represent 26 species of snakes, 4 species of lizards, and l amphisbaenian. The herpetofauna is essentially modern; 21 of 26 snake species, 2 of 4 lizard species, and the amphisbaenian survive in Florida today. Three Inglis IA snakes now extinct are Diadophis elinorae, Xenodontinae (cf. Dryinoides), and Regina intermedia (n. sp.). The extant species Opheodrys vernalis and Heterodon nasicus are present in the Inglis IA fauna and have apparently been replaced in Florida by Opheodrys aestivus and Heterodon simus. The lizards include Ophisaurus ventralis, Sceloporus undulatus, Gerrhonotus, and an extinct new species, Eumeces carri. The amphisbaenian is Rhineura cf. R. floridana. The ecological requirements of modern counterparts of the fauna suggest that Inglis IA represents a community from a region of high pine with xeric hammock interspersed. This open high pine country was part of a savanna that extended around the Gulf of Mexico during the late Cenozoic. The savanna apparently served as a corridor for mammals going to and from South America, but it did not act in the same capacity for the squamate fauna, which remained essentially autochthonous. The composition of the squamate fauna suggests that this corridor maintained a connection to the west that had previously existed farther north.