Equus occidentalis

Equus occidentalis (commonly known as the western horse) is an extinct species of wild horse that once inhabited North America, specifically the Southwestern United States, during the Pleistocene epoch. Some researchers to consider it a nomen dubium, as it was first described from three teeth with insufficient diagnostic characters, one even being suggested to be a separate taxon related to the American zebra. This taxonomic debate is yet to be fully resolved.