What is the name of the early horse known from the Eocene of North America?

The early horse known from the Eocene of North America is Hyracotherium.

Hyracotherium lived about 55 to 45 million years ago, near the beginning of the Eocene. It was much smaller than a modern horse—roughly fox- or small-dog-sized—and lived in wooded environments where it browsed on leaves, fruit, seeds, and soft shoots. Fossils attributed to early members of the horse family have been found widely in North America.

Its feet show how different early equids were from modern horses: it had four toes on each forefoot and three on each hind foot. Its low-crowned teeth suited a diet of softer vegetation rather than the abrasive grasses eaten by many later horses.

A common mix-up is the name Eohippus, meaning “dawn horse.” Older textbooks often treated Eohippus as a synonym of Hyracotherium, but modern classifications separate some North American species into other genera. Hyracotherium remains the traditional and widely recognized quiz answer for this early horse.