1. The origins of the horse go back to eohippus, the "dawn-horse"
of the Eocene, only 10 to 20 inches tall. Like its relatives, the ancient
tapir and rhinoceros, eohippus had four toes on its front feet, three on
the rear, and teeth adapted to a forest diet of soft leaves. Eohippus died
out about 50 million years ago in both North America and Europe.
Later ancestral horse types moved from their forest niche out on to the
grassy plains. Their teeth had to accommodate to hard siliceous grass. No
longer could these proto horses slip away through thick forest when danger
threatened. Escape now demanded speed and endurance. Limbs grew longer.
Extra toes became vestiges that were not visible externally.
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