Orohippus

fossil mammal genus

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Last updated

July 1, 2026

Quick Summary

Orohippus was a genus of very small, early horses that lived during the Eocene Epoch. These mammals are characterized by having four complete toes on their front feet and three on their hind feet. Their molar teeth featured tubercles that were partially fused into ridges.1

Orohippus succeeded Hyracotherium (also known as Eohippus), which is considered one of the earliest known horses. Hyracotherium was small, standing about 1 to 2 feet tall at the shoulder, and had four toes on its front feet and three on its hind feet, though functionally it used three toes on each foot, each ending in a small hoof. These early horses were browsers, feeding on leaves rather than grass.2

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Eohippus
Hyracotherium was succeeded by Orohippus, which differed from Hyracotherium primarily in dentition.
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Hyracotherium was succeeded by Orohippus, which differed from Hyracotherium primarily in dentition.
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horse
Evolution of the horse
Orohippus, a genus from the middle Eocene, and Epihippus, a genus from the late Eocene, resembled Eohippus in size and in the structure of the limbs. But the form of the cheek teeth—the four premolars and the three molars found in each half of both…
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Orohippus, a genus from the middle Eocene, and Epihippus, a genus from the late Eocene, resembled Eohippus in size and in the structure of the limbs. But the form of the cheek teeth—the four premolars and the three molars found in each half of both…
Read More