ECOLOGY OF EARLY EOCENE SAN JUAN BASIN, NM PHENACOLEMUR JEPSENI WITH PHENACOLEMUR CITATUS AND PHENACOLEMUR PRAECOX FROM BIGHORN BASIN, WY: A STUDY OF MICROWEAR AND DENTAL VARIATION AS A PROXY FOR EOCENE CLIMATE CHANGE

Phenacolemur was a widespread genus of Plesiadapiforms (primate-like animals) that lived from the late Paleocene to early Eocene of North America and Europe. Members of this genus were small, varying in size from that of a mouse (121 grams for Phenacolemur jepseni) to that of a large squirrel (414 grams for Phenacolemur praecox). Phenacolemur developed enlarged incisors and a reduced dentition. Phenacolemur species superficially appear to have a strong similarity in their dental characteristics but with closer observation, it becomes clear there is significant variation in tooth number, morphology, and dental wear between Phenacolemur species. These variations can be interpreted to be adaptations for different diets and evidence of evolutionary adaption to paleo-environments. Teeth are involved in food acquisition and their morphology reflects food acquisition strategy. Using SEM dental microwear analysis, along with dental morphology and statistical analysis, I show distinctions between three of the closely related species (P. jepseni, P. citatus, and P. praecox). These differences in dentition between Phenacolemur species reflect differences in diet, and indicate paleo-environmental/evolutionary adoptions in this early primate that permitted closely related (basal and derived) Phenacolemur species to live in the same areas of the San Juan Basin, NM and Bighorn Basin, WY concurrently.