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. The genus was originally identified by a closed off preorbital fossa, but later examinations of the cheek teeth, specifically the lower
cheek teeth, of
Cormohipparion specimens found that they were indeed valid and distinct from
Hipparion. A reappraisal of many horse genera was thus conducted in 1984, and the proposed synonymy was not acknowledged by later literature.
C. ingenuum holds the distinction for being the first prehistoric horse to be described in Florida, as well as being one of the most common species of extinct three-toed horses found to be in Florida, lasting until the early Pliocene.
Cormohipparion emsliei has the distinction of being the last hipparion horse known from the fossil record. The genus is considered to represent an ancestor to
Hippotherium. Its fossils have been recovered from as far south as Mexico. Fossils have been found in the Great Plains and Rio Grande regions of North America, Mexico, Florida, and Texas, which shows that they were herding animals. Fossils have been unearthed in
California,
Louisiana,
Nebraska,
South Dakota,
Honduras,
Costa Rica, and
Panama. Fossils have also been found in
India and
Turkey. == Evolution ==