Meeting Abstract
Emydid turtles (Testudines: Emydidae) are the most diverse and widespread family of turtles in the New World today. The fossil record of emydids is made up mostly of fragmentary remains from several main fossil regions, including Florida, Nebraska, and Kansas. Today the family consists of 10 to 12 extant genera and over 50 species. While the fossil record has a relatively high amount of disparity, many of the fossil taxa are fragmentary and have later been synonymized with other taxa, reinterpreted as being members of other families, or considered nomina dubia. The Gray Fossil Site, in eastern Tennessee, is a fossil locality interpreted as an ancient pond-like sinkhole from the latest Miocene-early Pliocene. The site has at least four fossil emydids including representatives of Trachemys, Chrysemys, Terrapene, and Emydoidea/Emys. All these turtles represent distinct species. Based on phylogenetic analyses, they show similarities with species from various geographic regions, suggesting these represent a non-analog turtle fauna. Trachemys haugrudi from the site is found to be closely related to fossil species from Florida. The new species of Chrysemys is most closely related to fossil Chrysemys from Nebraska, although the latter is Pleistocene in age. A new species of Terrapene lies outside crown Terrapene and near the base of the Terrapene clade while also being most closely related to species from the midwestern United States. The fourth, enigmatic emydid shows affinities with Emydoidea and Emys. If a member of the former genus, it would represent the southern-most extent of Emydoidea, modern or fossil, whose modern biogeographic range extends to central Indiana. The distinct turtle fauna at the Gray Fossil Site provides significant new information in our understanding the evolution of the emydids.
