Mesonyx

Mesonyx ("middle claw") is an extinct genus of mesonychid, one of two families that is part of the extinct order Mesonychia. Mesonychians were a clade of hoofed mammals closely related to ungulates, that first appeared in the fossil record during the Early Paleocene, roughly 63 million years ago. However, the order is thought to have arisen in the Late Cretaceous at least 66.7 Ma. Fossils of the various species in both North America and East Asia. The North American species, M. obtusidens were found from Bridgerian to middle Uintan localities of the Early to Middle Eocene in North America. On the other hand, M. uqbulakensis and M. nuhetingensis, were exclusive to the Arshantan of the Early Eocene in East Asia. Mesonychids within the Bridger Formation were thought to have been one of the top predators of the time along with crocodyliforms and the oxyaenid Patriofelis. Mesonyx was the type genus of Mesonychidae, which was coined by Cope (1875). Cope (1875) classified mesonychids as carnivorans instead of "Creodonta" due to trochelar face of the astragalus is completely grooved above as seen with true carnivorans. However, Cope would later reclassify mesonychids as creodonts.