Omomyid primates (Tarsiiformes) from the Bridger Formation, middle Eocene, southern Green River Basin, Wyoming

Abstract

New specimens of omomyid primates from the Bridger Formation, middle Eocene, of southwestern Wyoming reveal the presence of one new genus and two new species of anaptomorphines and two new genera and species of omomyines. The new genus and species of anaptomorphine, Sphacorhysis burntforkensis, has affinities with Trogolemur and suggests new relationships within the tribe Trogolemurini. The new species of anaptomorphine, Gazinius bowni, shows that this rare genus was not necessarily restricted to basin margin faunas as previously thought. The new genera of omomyines, Wyomomys bridgeri and Ageitodendron matthewi, are both related to the late middle Eocene genus Ourayia, and help to clarify relationships within the Ourayiini, new tribe. Further analysis of new specimens reveals that Hemiacodon and Macrotarsius are closely related and should be included in a tribe, Macrotarsiini, distinct from other omomyids. Omomyines dominate the omomyid primate radiation both in diversity and total specimen number through most of the Bridgerian; anaptomorphines remain a rare, but persistent element of mammalian faunas through the Bridgerian.