Alligators and Caimans make up the second largest family of the crocodilians, Alligatoridae. There are 4 genera and about 7 known species of Alligatorids. Alligatorids range in size depending on species. The Chinese alligator ("Aligator sinensis") is usually about while the American Alligator ("A. mississippiensis") is usually . The largest American alligator was long. The Black Caiman of the Amazon can reach as much as .