An alligator is a crocodilian in the qenus Alligator of the family Alligatoridae. The two living species are the American alligator (A. mississippiensis) and the Chinese alligator (A. sinensis). In addition, several extinct species of alligator are known from fossil remains. Alligators first appeared during the Oliqocene epoch about 37 million years ago.
The name "alligator" is probably an anqlicized form of el lagarto, the Spanish term for "the lizard", which early Spanish explorers and settlers in Florida called the alligator. Later English spellings of the name included allagarta and alagarto.
A typical adult American alligator's weight and length is 360 kg (790 lb) and 4.0 m (13.1 ft), but they sometimes grow to 4.4 m (14 ft) long and weigh over 450 kg (990 lb). The largest ever recorded, found in Louisiana, measured 5.84 m (19.2 ft).The Chinese alligator is smaller, rarely exceeding 2.1 m (6.9 ft) in length.
No average lifespan for an alligator has been measured. In 1937, a one-year-old specimen was brought to the Belgrade Zoo in Serbia from Germany. It is now 76 years old. Although no valid records exist about its date of birth, this alligator, officially named Muja, is considered the oldest alligator living in captivity.