Alligator

An alligator, or colloquially gator, is a large reptile in the Crocodilia order in the genus Alligator of the family Alligatoridae. The two extant species are the American alligator (A. mississippiensis) and the Chinese alligator (A. sinensis). Additionally, several extinct species of alligator are known from fossil remains. Alligators first appeared during the Oligocene epoch about 37 million years ago. The name "alligator" is probably an anglicized form of , the Spanish term for "the lizard", which early Spanish explorers and settlers in Florida called the alligator. Early English spellings of the name included allagarta and alagarto. Evolution Alligators and caimans split in North America during the early Tertiary or late Cretaceous (about 53 million to about 65 million years ago). The Chinese alligator split from the American alligator about 33 million years ago and probably descended from a lineage that crossed the Bering land bridge during the Neogene. The modern American alligator is well represented in the fossil record of the Pleistocene. The alligator's full mitochondrial genome was sequenced in the 1990s. The full genome, published in 2014, suggests that the alligator evolved much more slowly than mammals and birds. Phylogeny The genus Alligator belongs to the subfamily Alligatorinae, which is the sister taxon to Caimaninae (the caimans). Together, these two subfamilies form the family Alligatoridae. The cladogram below shows the phylogeny of alligators.