New Mexico Geological Society Annual Spring Meeting — Abstracts

Plesiadapiformes (possible stem-primates) proliferatedaround the world during the Paleocene-Eocene with a large sample found in the San Juan Basin of New Mexico.The Paleocene-Eocene Thermal Maximum (PETM) occurred 56 million years ago, and is considered the most extreme change in the Earth's climate during the Cenozoic Era. This global warming event is linked to the extinction of many plesiadapiformes, and the rise of “true” primates (euprimates).Geographic range has a strong effect on extant primate species. Dispersal can be estimated for plesiadapiformes by using fossil localities. Estimates suggest a positive correlation between geographic range and generic diversity at the clade-level for larger plesiadapiforms (ex. plesiadapids r= .764, n= 12, p= .004). However, there is no correlation in smaller plesiadapiforms (i.e. paromomyids, picrodontids, palaechtonids, and microsyopids). Plesiadapiformes were a highly diverse order with >9 families and >150 genera. These basal primates varied in size from small, mouse-like species (7 gram Micromomysvossae) to that of cat-sized species (3,055 gram Plesiadapiscookei).To better understandplesiadapiform paleogeographic-dispersal and climate adaptations, it is necessary to have an extant, analogous species to compare them to. This study will look at anumber of living species: metatherian phalangeriformes (Trichosurus vulpecula, Didelphis orientalis, and Petaurusbreviceps), rodents (Sciurusspecies), dermoptera (Galeopterus variegatus), and prosimians (Microcebus species). New correlations (comparing m1 area body massand microwear dietary types) provide insights into dispersal regression models that failed to correlate between range and fossil genus biodiversity.New Mexico fossil data suggests that small plesiadapiforms’ geographic dispersal was highly controlled by size and diet (both factors highly affected by the PETM).Plesiadapiform groups that showed no correlation (ex. paromomyids r= .292, n= 27, p= .139) now show a positive correlation between body mass, diet type, and paleogeographic-dispersal (r= .690, n= 9, p= .05).