This is also supported by wear facets on the molars of M. annectens and M. kratos that are indicative of heavier shearing and crushing forces required of harder foods like fruits and nuts.

[10] Consistent with other North American members of Microsyopidae, Microsyops has a lower central incisor that is enlarged, procumbent, and lanceolate.

The fourth lower premolar has a distinct metaconid, no paraconid, and a two-cusped talonid with a more fully-developed basin than in the closely related Arctodontomys.

[9] Additionally, Microsyops upper molars lack a postprotocingulum, in contrast to the condition found in most early Paleogene primates.

Based on basicranial features, the internal carotid artery which supplied blood to the brain of Microsyops was primitive with respect to both extinct and extant euarchontans.

He compared lower jaw fragments, found by Dr. J. V. Carter in the Bridger Basin of southwestern Wyoming, to the condylarth Hyopsodus gracilis, named by Professor O. C. Marsh of Yale University.

Two families of plesiadapiforms, Microsyopidae and Paromomyidae, have representative taxa from the Uintan Land-Mammal Age (middle Eocene) while the Plesiadapidae and Carpolestidae disappeared at the end of the Paleocene.

In a cladistic analysis including postcranial, cranial, and dental characteristics by Bloch et al. (2007),[15] microsyopids were found to be plesiadapiforms more distantly related to euprimates than plesiadapoids or paromomyoids, and without any special relationship to dermopterans.

[14] However, while analyses support a euarchontan grouping, specific relationships of microsyopids to other plesiadapiforms, euprimates, scandentia, and dermoptera remain unresolved.

Microsyops has larger EQ than Plesiadapis cookei, and falls in the lower range of estimates for early Paleogene primates.

However, basicranial anatomy is remarkably primitive, because the auditory bulla was not ossified and there are only grooves, rather than bony tubes, for the intrabullar parts of the internal carotid artery and its dependencies.