PARENT SESSION
Oral Session # 2: Paleoecology.
Presiding: B Lynch
Monday, August 4. 8:00 AM to 11:30 AM, SITCC Meeting Room 101.
North American Quaternary Squamata: Re-evaluation of the stability hypothesis.
Bell, Christopher*,1, Gauthier, Jacques2, 1 The University of Texas at Austin, Austin, TX2 Yale University, New Haven, CT
ABSTRACT- The last four decades saw a dramatic increase in knowledge of Quaternary squamate reptiles in North America. Initial research centered on primary descriptive accounts of faunas, but these were recently supplemented by synthetic regional summaries, and efforts to place the reptiles in a broader context of faunal dynamics in the Pleistocene and Holocene. The picture that emerged from these studies suggests that squamate reptiles were taxonomically and geographically stable throughout much of the Quaternary. In stark contrast to the mammals and birds, few extinctions and no significant geographic range adjustments are reported for reptiles at the end of the Pleistocene. Phylogenetic systematics has yet to play an important role in Quaternary vertebrate paleontology, but it presents a potentially fruitful alternative philosophical and methodological approach. Our recent re-evaluation of the stability hypothesis was based on this approach and leads to several important conclusions: 1. This hypothesis suffers from circularity because many fossil identifications ultimately are based on the modern geographic distribution of taxa; 2. Due to their incomplete nature and our current understanding of morphological synapomorphies for squamates, species-level taxonomic resolution is not possible for the majority of Quaternary fossils; 3. Geographic and taxonomic stability is demonstrable at more-inclusive taxonomic levels, but is not particularly informative with respect to questions typically asked by Quaternary paleontologists; 4. To answer species-level questions, we must seek synapomorphies in the isolated skeletal elements commonly preserved in Quaternary deposits. Utilization of phylogenetic systematics in Quaternary studies will require an effort to seek synapomorphies in materials typically recovered from Quaternary deposits, acceptance of the taxonomic limitations of the data with which Quaternary paleontologists work, and a willingness to frame questions in a phylogenetic context.
Key words: reptiles, climate change, herpetology, Pleistocene