ABSTRACT
Plesiadapiform primates are known almost exclusively from fragmentary jaws and teeth. Definitely assignable skeletal remains are known of only two closely related genera, Plesiadapis and Nannodectes. The identification of species and genera among the Plesiadapiformes and the arrangement of these genera into families varies somewhat from one author to another, depending upon their respective taxonomic philosophy and areas of expertise. Two genera are provisionally placed in the Microsyopidae: Micromomys, from the late Paleocene of Wyoming and Saskatchewan and Tinimomys, from the earliest Eocene of Wyoming. These two genera are among the smallest of all known primates. F. S. Szalay and R. L. Decker, and Szalay and his team. have argued that Plesiadapis shares with all other primates a suite of characters in the talus and humero-radial articulation that are indicative of a basically arboreal adaptation.
