Abstract

Two amphibian taxa are reported for the first time from the lower to middle Miocene shallow-marine Calvert Formation. These are Batrachosauroides aff. B. dissimulans (a large proteoid salamander) and cf. Notophthalmus robustus (a small newt). Four kinds of identifiable nonmarine turtles were reported previously from this formation. These are Bairdemys miocenica (a pleurodire), Kinosternon sp. (a musk turtle), Hesperotestudo ducateli and Hesperotestudo wilsoni (tortoises). Four additional taxa reported here are Chrysemys isoni n. sp. (a painted turtle), Trachemys sp. (a pond turtle), Floridemys hurdi n. sp. (a small tortoise), and Apalone lima (a softshell turtle). Most of these taxa are known from elsewhere in the Atlantic and Gulf Coastal Plains from New Jersey to Texas. The regional widespread occurrence of many of these taxa indicates that they represent a modestly diverse community of amphibians, fresh water turtles, and land turtles that were endemic to the Atlantic and Gulf coastal regions of the United States during the late early and early middle Miocene. Their pattern of distribution is similar to that of eastern American land mammals during this time interval, indicating that the Atlantic and Gulf coastal plains of the southeastern United States then lay within a single climatic zone that constituted a distinctive and long-lived faunal province throughout the early and middle Miocene (Hemingfordian through Barstovian land mammal ages).

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