Sub-class Placentalia

Order Perissodactyla

Family Equidae (horses, asses, zebras)

Species Equus scotti

The family Equidae originated in North America. Species of the genus Equus, which includes living horses and zebras, first appeared in the early Pliocene, around five million years ago. Thereafter they differentiated into dozens of species, many of which lived in the New World (including South America) until the end of the Pleistocene. All had the same basic body plan, reflecting adaptations for swift running. Although in Europe Equus was pictured frequently by Stone Age artists, direct association between humans and horses in the American Pleistocene has not been confirmed. The half-dozen or so species of New World Equus disappeared at or before 11,000 years ago. However, well prior to its disappearance in the New World, Equus managed to invade Eurasia by crossing the Bering landbridge westward. In Eurasia, one species, E. caballus, was eventually brought into domestication; around AD 1500, this species was reintroduced into the ancestral homeland of Equus by the Spanish conquistadores.

See also: Kurtén, B., and E. Anderson, 1980. Pleistocene Mammals of North America. Columbia University Press: New York.