Four genera of primates are present in the early to mid-Duchesnean Lac Pelletier Lower Fauna. Phenacolemur leonardi sp.nov., Trogolemur sp., Omomys sp., and Macrotarsius cf. M. montanus make up the latest diverse primate assemblage known from North America and from the Great Plains. This primate assemblage is similar to the earliest Duchesnean assemblage from the Wood locality, Badwater Creek area of central Wyoming, and primate genera appear to have been widely distributed through the Great Plains and Rocky Mountains in the Uintan–Duchesnean.