Pronghorn, Yellowstone National Park, Wyoming

Looking at those skinny legs, it’s hard to believe that the pronghorn is the second fastest land mammal on earth (only slightly slower than the cheetah — although it can maintain speed over a greater distance than the cheetah). In fact, the pronghorn can easily outpace any predator on the North American continent, leading experts to believe that it developed its great speed due to a now extinct predator — perhaps the American cheetah, of which exist skeletal records. Nikon D300 with Nikkor 200-400mm lens (at 380mm) ISO 400, f/4 at 1/800th of a second.