An alligator is a crocodilian in the genus Alligator of the family Alligatoridae. There are two living alligator species: the American alligator and the Chinese alligator. In addition, several extinct species of alligator are known from fossil remains. Alligators first appeared about 37 million years ago. A large adult American alligator's weight and length is 800 pounds and 13 feet long, but can grow to 14.5 feet long and weigh over 1,000 pounds. Alligators are only native to the United States and China. American alligators are found in the southeast United States: all of Florida and Louisiana, the southern parts of Georgia, Alabama and Mississippi, coastal South and North Carolina, Eastern Texas, the southeast corner of Oklahoma and the southern tip of Arkansas. Although alligators have a heavy body and a slow metabolism, they are capable of short bursts of speed, especially in very short lunges. Alligators' main prey are smaller animals that they can kill and eat with a single bite. Alligators may kill larger prey by grabbing it and dragging it into the water to drown. Alligators consume food that can not be eaten in one bite by allowing it to rot, or by biting and then spinning or convulsing wildly until bite-size chunks are torn off. This is referred to as a "death roll." Critical to the alligator's ability to initiate a death roll, the tail must flex to a significant angle relative to its body. An alligator with an immobilized tail cannot perform a death roll.