[3] Specimens have been found from southern Mexico[4] to southern South Dakota and in Alberta, Canada,[2] at sites such as Gypsum Cave and Natural Trap Cave, as well as eastern Beringia in Yukon[3] A later study found that Equus cedralensis from the Late Pleistocene of Mexico also belonged to this species.

[5] The earliest species of the lineage appeared in North America during the Late Pliocene to Early Pleistocene, around 2 to 3 Ma.

It is estimated to have diverged from modern Equus around 4.1–5.7 million years ago, during the late Hemphillian or early Blancan.

[3] †Hippidion †Haringtonhippus Equus ferus (wild horse) †Equus ovodovi Subgenus Asinus (asses) Subgenus Hippotigris (zebras) Some other authors have argued that the species should be retained in the genus Equus, due to its morphological similarity to members of that genus.

[4] Dental mesowear analysis of specimens from Natural Trap Cave in Wyoming suggest that the species regularly consumed abrasive vegetation.