Mesohippus

The "middle horse" earned its name. Mesohippus is intermediate between the eohippus-like horses of the Eocene, (which don't look much like our familiar "horse") and more "modern" horses.

Where & When? Fossils of Mesohippus are found at many Oligocene localities in Colorado and the Great Plains of the US (like Nebraska and the Dakotas) and Canada. This genus lived about 37-32 million years ago.

How was Mesohippus intermediate between the ancient Eocene horses and the later, more modern forms?

The Eocene predecessors of Mesohippus had four toes on their front feet, but Mesohippus lost the fourth toe.

At left, the front foot of Hyracotherium. At right, the front foot of Mesohippus.