Close-up of a male Pronghorn (Antilocapra americana). OK it's not technically an antelope - this species is most closely related to Giraffe and Okapi. Evolved, like the African antelope species, to outrun predators, the Pronghorn proved very hearty and successful. They outlived the North American species of cheetahs that went extinct in pre-historic times. Incredibly fast (only the Cheetah achieves faster speeds on land), the Pronghorn have the added advantage of being able to sustain their top speed for miles. Custer State Park, Black Hills, South Dakota.