This is a Chinese Alligator (Alligator sinensis) at the Knoxville (Tennessee) Zoo.
While there are more than 20 species of crocodile, there are only two species of alligator. Most people are familiar with the American Alligator (Alligator mississippiensis), but the Chinese alligator is extremely rare. There may be fewer than 200 individuals still in the wild, mostly in the Anhui province in the lower Yangtze River. They are quite a bit smaller than their American counterparts, only reaching 5-7 feet (1.5 to 2.1 meters) at maturity.