Just behind the cheetah, the pronghorn antelope is the second fastest animal in the world, clocking up to 65 miles per hour. But unlike the cheetah, it can run for hours at top speeds. Within North America, the pronghorn antelope is the fastest hoofed animal. When they run they keep their mouths open to take in extra oxygen. But, pronghorn antelope aren’t good jumpers. They go under, rather than jumping, fences. When leaping across grasslands the antelope become startled, they raise the white hair on their behinds, signaling any danger to other antelope up to two miles away.