A pronghorn is a swift, graceful animal that looks like an antelope and lives in the open grasslands and deserts of western North America. Pronghorns are famous for being the fastest land animal in the Western Hemisphere: they can sprint at speeds over 55 miles per hour and maintain 30 miles per hour for miles without stopping. Only cheetahs are faster, but cheetahs can't run nearly as long.

The pronghorn gets its name from the unusual horns on its head, which have a small forward-pointing branch, or prong. Both males and females have these distinctive horns. Unlike deer antlers that fall off and regrow each year, pronghorn horns have a bony core that stays attached, though the outer sheath sheds each year.

These animals evolved their incredible speed over millions of years, probably to escape predators like the now-extinct American cheetah. Today, even though those ancient predators are gone, pronghorns have kept their blazing speed. When alarmed, they can spot danger from miles away with their huge eyes (the largest of any North American land mammal), then race across the plains in long, bounding strides.

Pronghorns aren't actually true antelopes, despite the resemblance. They're the last surviving member of a unique family of animals found nowhere else on Earth.