New Mexico Geological Society Annual Spring Meeting — Abstracts

Phenacolemur was a late Paleocene-early Eocene paromomyid plesiadapiform from western North America and Europe. Several species are distinguished by differences in size and subtle differences in tooth morphology. There are questions regarding the validity of at least one species, P. jepseni, a taxon originally named from the early Eocene of NM. Some workers have suggested that P. jepseni is a junior subjective synonym of P. citatus or P. praecox. Specimens from the Bighorn Basin are purported to show a continuum in size and morphology that overlap with samples of P. jepseni from NM. There are a limited number of P. jepseni teeth collected. However, by looking at the larger collections of P. citatus and P. praecox, I have compared trends using metric data and physical morphology. These results show patterns and variations between the three closely related species. Statistical analyses indicate these three species to be distinct, yet highly variable, with characteristics that show intermediate stages between samples. Morphologically P. jepseni specimens are smaller, lack a paraconid on m2 (present on P. citatus and P. praecox), and have an upper canine not seen in other Phenacolemur species. With these results, I argue P. jepseni is a valid species.