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Yellowstone Winter Wonderland

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Male Pronghorn (Antilocapra americana) sauntering across a frozen field. Pronghorn are the fastest land mammals in the Western Hemisphere, and only the Cheetah is faster. Scientists speculate that the Pronghorn, being built for maximum predator evasion through running, evolved to escape from extinct predators such as the American cheetah. Its speed greatly exceeds that of any existing North American predators. The Pronghorn has a large windpipe, heart, and lungs to allow it to take in large amounts of air when running. Additionally, their hooves have two long, cushioned, pointed toes that absorb shock when running at high speeds. They also feature an extremely light bone structure and hollow hair. [Adapted from Wikipedia]
Fastest in the New World