
The order Crocodilia includes the true crocodiles (family Crocodylidae), the alligators and caimans (family Alligatoridae), and the gharial and false gharial (family Gavialidae). Members of the order's total group, the clade Pseudosuchia, appeared about 250 million years ago in the Early Triassic period, and diversified during the Mesozoic era.

They first appeared 95 million years ago in the Late Cretaceous period ( Cenomanian stage) and are the closest living relatives of birds, as the two groups are the only known survivors of the Archosauria. Clockwise from top-left: saltwater crocodile ( Crocodylus porosus), American alligator ( Alligator mississippiensis), and gharial ( Gavialis gangeticus)Ĭrocodylia distribution on land (green) and at sea (blue)Ĭrocodilia (or Crocodylia, both / k r ɒ k ə ˈ d ɪ l i ə/) is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians.
