ON THE IDENTIFICATION OF FOSSIL SALAMANDERS AND SNAKES: A CASE STUDY FROM THE MIO-PLIOCENE GRAY FOSSIL SITE OF TENNESSEE

The Mio-Pliocene Gray Fossil Site of northeastern Tennessee is primarily composed of laminated fossiliferous clay sediments that indicate a ponded environment. The bulk of the reptiles and amphibians found up to this point (alligators, natricine snakes, aquatic testudines and anurans, and salamanders) reflect this ecological setting. Recent screenwashing efforts have produced an abundance of salamander and snake trunk vertebrae, the main elements used in the identification of fossils from these groups. Comparison with extant species revealed problems with the diagnosis of these taxa to lower levels of classification using currently published criteria. Similar troubles have recently been addressed with the identification of anurans, testudines, and small mammals. Examples of these problems in extant and fossil salamanders and snakes are discussed. The primary issues are: 1) ontogenetic, interspecific, intraspecific, and intercolumnar vertebral variation has not been accounted for, 2) discrete characters are not relied upon, and 3), too much reliance has been placed on modern biogeography.