Horses, those majestic, slender creatures that play football on
Budweiser commercials had a humble beginning at the start of the
Eocene. Horses began as a small fawn-looking animal called
Hyracotherium. Eating shrubs in the swampy forests of North
America and Europe, Hyracotherium had the need for speed. With
its four-toed hooves, it could outrun any modern Olympic track
star (or any vicious carnivore predator). By the Oligocene,
horses had more-than-doubled their size. They were now almost
two feet long. This new breed was called Mesohippus (Mesohippus
later evolved into a larger version, Miohippus). But instead of
having 4 toes, Mesohippus had 3, with a big toe in the middle.
It could now run with greater ease. Now looking much more like
the modern horse, the pony-sized Merychippus ran on its extra-
large toe. The other toes, becoming more and more useless, began
to shrink away. Merychippus also adapted for plains life in the
Miocene: it got tougher teeth for tougher grass. Horses
developed more during the P