Brevirostres

Brevirostres is a group of crocodilians that, as originally formulated, included alligatoroids and crocodyloids, but not gavialoids. Results of molecular phylogenetic analysis uniformly draw gavialoids and crocodyloids into a close relationship; in that case, Brevirostres becomes redundant with Crocodilia.

Members of brevirostres are crocodilians with small snouts, and are distinguished from the long-snouted gharials. It is defined phylogenetically as the last common ancestor of Alligator mississippiensis (the American alligator) and Crocodylus niloticus (the Nile crocodile) and all of its descendants. This classification was based on morphological studies primarily focused on analyzing skeletal traits of living and extinct fossil species, and placed the gharials outside the group due to their unique skull structure, and can be shown in the simplified cladogram below:

However, recent molecular studies using DNA sequencing render Brevirostres redundant with Crocodylia upon finding the crocodiles and gavialids to be more closely related than the alligators. The new clade Longirostres was defined by Harshman et al. in 2003, and can be shown in the cladogram below: