Morphology of the humerus of Hapalodectes (Mammalia, Mesonychia). American Museum novitates ; no. 3242

Abstract

"A distal humerus of the primitive mesonychian Hapalodectes cf. leptognathus from the early Eocene of Colorado reveals that Hapalodectes was less cursorially derived than were other members of the Mesonychidae such as Dissacus and Mesonyx. The humerus has a moderately long deltopectoral crest, a relatively wide distal articular surface with a cylindrical capitulum, a relatively broad entepicondyle with an entepicondylar foramen, and a shallow olecranon fossa that lacks a supratrochlear foramen. These skeletal features are associated with terrestrial locomotion but not with cursoriality. This specimen represents some of the first data on the postcranial skeleton of this taxon, data that are relevant both to determination of the sister taxon of Cetacea and for resolving whether or not Mesonychia is paraphyletic"--P. [1].