New plesiadapiform primates from the Eocene of Wyoming and Montana

Several recently discovered fossil specimens add to our knowledge of plesiadapiform primates. Micromomys willwoodensis, new species, is a diminutive microsyopid from the early Eocene (early Wasatchian) Willwood Formation of the Clark's Fork Basin, Wyoming. It is larger and more specialized than late Paleocene M. vossae and M. silvercouleei. Elwynella oreas is a new genus and species of paromomyid from the middle Eocene (early Bridgerian) Aycross Formation of northwestern Wyoming. It is most closely related to Phenacolemur, but differs from all other post-Tiffanian paromomyids in retention of P3 and in details of incisor morphology and molar trigonid structure. New specimens of the microsyopid Tinimomys graybulliensis are described, including a nearly complete dentary from the Wasatchian of the Bighorn Basin and the first record from probable Clarkforkian (latest Paleocene–earliest Eocene) beds of the Powder River Basin. The first Wasatchian specimen of Plesiadapis is described and illustrated.