American Pronghorn

American Pronghorn (Antilocapra americana)

Entirely unique on this planet, the Pronghorn's scientific name, Antilocapra americana, means "American antelope goat." But the deer-like Pronghorn is neither antelope nor goat -- it is the sole surviving member of an ancient family dating back 20 million years.
The Pronghorn is the only animal in the world with branched horns (not antlers) and the only animal in the world to shed its horns, as if they were antlers. The Pronghorn, like sheep and goats, has a gall bladder, and like giraffes, lacks dewclaws. If that weren't enough, the Pronghorn is the fastest animal in the western hemisphere, running in 20-foot bounds at up to 60 miles per hour. Unlike the Cheetah, speedburner of the African plains, the Pronghorn can run for hours at quite a fast pace.

Source: Desert USA