Meeting Abstract
I performed a phylogenetic analysis of gerrhonotine lizards in an effort to elucidate the phylogenetic position of a well preserved fossil skull. The fossil was collected from Pliocene sediments in the Anza-Borrego Desert State Park in southern California. The results of my analysis allow me to refine the taxonomic resolution of the fossil skull, which represents the first fossil to be assigned to the gerrhonotine genus Elgaria using apomorphies. The age of the fossil is constrained by magnetostratigraphy and falls within a time period of rapid diversification of species of Elgaria based on previous molecular estimates. I addressed the lack of comparative skeletal data for extant gerrhonotine species through the use of high resolution x-ray computed tomography (HRCT).The lizard group Gerrhonotinae contains over 50 extant species which inhabit diverse environments across western and south-central United States, Mexico, and Central America. Although previous authors examined the osteology of species within Gerrhonotinae, their studies were limited because skeletal data are exiguous or nonexistent for many extant species. I obtained permission from museums to borrow alcohol-preserved gerrhonotine specimens for HRCT scanning. I built a diverse comparative dataset of the osteology of 17 species, representing the major clades within the group. This is the most diverse sample of osteological data for species of Gerrhonotinae to date. HRCT permitted me to examine morphology that was obscured on the physical fossil and analyze the phylogenetic placement of the fossil skull. My preliminary results indicate that the fossil has a close relationship with Elgaria velazquezi. The close affinity of the fossil with a species endemic to the Baja California peninsula provides evidence for deciphering the diversification and paleobiogeography of Elgaria.
