A new species of the basal plesiadapiform Purgatorius (Mammalia, Primates) from the early Paleocene Ravenscrag Formation, Cypress Hills, southwest Saskatchewan, Canada: further taxonomic and dietary diversity in the earliest primates

Abstract

The fossil record of the earliest primates, purgatoriid plesiadapiforms, has become increasingly well documented during the past two decades, but their dietary preferences remain poorly understood. While the available evidence, which consists mostly of isolated teeth and incomplete jaws with teeth, suggests that purgatoriids were insectivorous to omnivorous, we describe here a new species of Purgatorius, Purgatorius pinecreeensis sp. nov., that extends the range of purgatoriid dental disparity toward greater omnivory than had been known before. Purgatorius pinecreeensis sp. nov., from the early Paleocene (Puercan) Ravenscrag Formation of southwestern Saskatchewan, differs from other species of Purgatorius in having slightly lower crowned teeth with a lower trigonid relative to talonid, blunter and more swollen major cusps, more transverse lower molar paracristids, and m3 with a more robustly developed posterior lobe. Taken together, these specializations enhanced the capacity for crushing and grinding at the expense of orthal shear, and represent the first instance of a modest degree of bunodonty in the family. The discovery of P. pinecreeensis sp. nov., along with other recently reported basal plesiadapiforms from the Puercan and Torrejonian of the northern Western Interior, lends additional support to the notion of a significant primate radiation soon after the Cretaceous–Paleogene extinction event.