One-toed horse partial skull

One-toed horse partial skull

NMMNH P-?

One-toed horse, Scott's horse

Horse, odd-toed ungulate

Arroyo de la Parida, Socorro County

Pliocene, about 3 million years ago

Partial skull with 10 upper teeth

Advanced one-toed horses of the genus Equus first appeared in North America in the Pliocene epoch about 4 million years ago. Species of Equus include all of the living horses, donkeys, and zebras, as well as a large number of extinct Ice Age (Pliocene and Pleistocene epochs) species from North America. Equus is characterized by the presence of high-crowned (hypsodont) teeth with a complicated enamel pattern adapted for browsing on coarse vegetation such as grasses, and long, slender limbs with a single digit and hoof, well-suited for rapid locomotion in open habitats such as grasslands.