COMMUNITY STRUCTURE ANALYSIS OF THE MAMMALS FOUND AT THE GRAY FOSSIL SITE, TN

The early Pliocene age Gray Fossil Site (GFS) is a recently discovered fossil site that preserves diverse fauna and flora, and represents one of only a few sites of its age in eastern North America. The assemblage of fauna found at GFS is unique compared to what has been found at other contemporaneous fossil sites in North America. Studying mammalian community structures at fossil sites can provide an abundance of information about the past environment and species adaptations to it, such as, niche occupation of species, resource partitioning, and interactions between organisms and their environment. While studies of the fauna and flora have helped us to understand the ecosystem at GFS, detailed study of the mammal community will help us better understand this unique site.

All of the mammal species from GFS, as well as the mammals from each of the five well-known contemporaneous fossil sites, and the twenty modern communities included in this study, have been categorized by body size, locomotor mode, and cheek tooth crown height to characterize the niches occupied by each species. Proportions of species within categories have been compared and analyzed across modern and fossil sites using discriminant function analysis (DFA). Results of the DFA demonstrate that modern communities with different climates and habitats can be distinguished based on the body size, locomotion, and cheek tooth crown heights of mammals living there. Moreover, functions can be used to infer conditions of past sites. Preliminary examinations of results show that GFS has more brachydont and scansorial species present, and fewer cursorial species than occur at other contemporaneous sites. The results of the discriminant functional analysis indicate that the GFS community structure is most similar to modern temperate regions of the Himalayan Mountains in China and the freshwater wetlands of the Everglades. Proportions of brachydont, gliding, and scansorial species appear to be driving variables behind these results.