UM 87990 Plesiadapis cookei was either an early primate or a closely related sister group, but in either event a type of basal primatomorph known as Plesiadapiform, and for a time was considered as a possible primate ancestor. (Image citation: Brain of Plesiadapis Cookei (Mammalia, Proprimates): Surface Morphology and Encephalization Compared to those of Primates and Dermoptera - Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/figure/UM-87990-skeleton-of-Plesiadapis-cookei-as-mounted-in-the-University-of-Michigan-Exhibit_fig1_30842037 [accessed 3 Mar, 2019]
Notharctus tenebrosus (left) and Plesiadapis cookei (right) — Image by Ghedoghedo, liscenced under CC BY-SA 3.0
PMO-214, “Ida” Darwinius masillae was probably an early member of the Stepsirrhini, although she has at time been suggested as possibly being an early member of the Haplorhini or as a “missing link” between the two groups. Ida is very similar to what we would expect from a basal primate.
