Cormohipparion

Cormohipparion is an extinct genus of horse belonging to the tribe Hipparionini that lived in North America during the late Miocene to Pliocene (Hemphillian to Blancan in the NALMA classification). The genus Cormohipparion was coined for the extinct hipparionin horse 'Equus' occidentale, described by Joseph Leidy in 1856. However it was soon argued that the partial material fell within the range of morphological variation seen in Hipparion, and that the members of Cormohipparion belonged instead within Hipparion. This rested on claims that pre-orbital morphology did not have any taxonomic significance, a claim that detailed study of quarry sections later showed to be false. A reappraisal of many horse genera was thus conducted in 1984, and the proposed synonymy was not acknowledged by later literature. The genus is considered to represent an ancestor to Hippotherium. Its fossils have been recovered from as far south as Mexico.