The Alligatoridae family of crocodylians includes alligators and caimans. == True alligators == The lineage including alligators proper (Alligatorinae) occurs in the fluvial deposits of the age of the Upper Chalk in Europe, where they did not die out until the Pliocene age. The true alligators are today represented by two species, A. mississippien... Found on http://en.wikipedia.org/wiki/Alligatoridae
(from the article `crocodile`) ...of pterygoids.Suborder EusuchiaUpper Jurassic to Recent; choanae entirely enclosed by pterygoids.Family Alligatoridae (alligators)Four genera and ... Found on http://www.britannica.com/eb/a-z/a/50