The Status of Emys twentei Taylor (Reptilia: Testudinidae) Based on New Fossil Records from Kansas and Oklahoma

Abstract

The finding of a partially complete specimen of the turtle, genus Emy- doidea, from early Yarmouthian (second) interglacial deposits in Seward Co., Kansas, has prompt- ed a reexamination of Emys twentei Taylor. Comparisons of the type-specimen with additional fossil material dating from the late Pliocene of Kansas and with Recent skeletons, indicate that all should be referred to Emydoidea blandingi (Holbrook). The fossil and modern distributions of E. blandingi are reviewed, including archaeological records. The accumulation of fossil specimens of the semi-box turtle, genus Emydoidea, during the past several years in the collection of the University of Michigan Museum of Paleontology, and the consequent necessity of including it in discussions of late Cenozoic herpetofaunas of the Great Plains, have prompted a reexamination of the status of the nominal species, Emys twentei Taylor (Emydoidea twentei, auct.). To date this is the only fossil Emydoidea to be discussed in detail in the literature. Many additional specimens from southwestern Kansas and the adjacent Oklahoma panhandle-spanning a geologic range from the late Pliocene to the Wisconsin of the Pleistocene-are now available for study. In this paper we shall discuss all fossil records, review the status of Emys twentei, mention records extralimital to the Recent distribution based on material from archaeological sites, and attempt to explain the major distributional changes of Emydoidea during the Ice Age. In examining the status of Emys twentei, we have compared the diagnostic characters list- ed by Taylor (1943) with the same characters in a skeletal series of the Recent species, Emy- doidea blandingi. Included for comparison is additional fossil material from the time periods in southwestern Kansas and nearby Oklahoma which correspond to Yarmouthian interglacial and Illinoian glacial times in glaciated North America. Specimens studied are in the University of Michigan Museum of Paleontology (UMMP), Uni- versity of Michigan Museum of Zoology (UMMZ), University of Kansas Museum of Natural His- tory (KU), American Museum of Natural History (AMNH) and Carnegie Museum (CM). The nomenclature used for turtle shell bones and epidermal shields, the latter here simply called scutes, is that suggested by Zangerl (1969).