[9] In this definition, "Crocodylia" specifically refers to descendants of the common ancestor of the three modern lineages of eusuchians: Gavialoidea (gharials), Alligatoroidea (alligators and caimans), and Crocodyloidea (crocodiles).

Whether certain families or genera qualify as basal eusuchians or non-eusuchian neosuchians is a matter of debate over which definition is used for the group.

This feature enables living crocodylians to safely breathe in through their nostrils while the rest of the head (including the mouth) remains submerged.

This structure reaches its greatest elaboration among eusuchians, in which the internal nares are completely surrounded by the pterygoid bones.

[10] A 2018 tip dating study by Lee & Yates using both molecular, morphological and stratigraphic data recovered the cladogram below:[3] Goniopholis† Bernissartia† Shamosuchus† Acynodon† Hylaeochampsa† Allodaposuchus† Lohuecosuchus† Borealosuchus† Eothoracosaurus† Thoracosaurus† Argochampsa† Eogavialis† Eosuchus† Planocraniidae† Crocodylia (crown) A 2021 Rio & Mannion phylogenetic study using a heavily modified morphological data set recovered the cladogram below:[11] Bernissartia fagesii† Isisfordia duncani† Theriosuchus pusillus† Shamosuchus djadochtaensis† Glen Rose Form Wannchampsus kirpachi† Acynodon iberoccitanus Hylaeochampsa vectiana Iharkutosuchus makadii Allodaposuchidae† Borealosuchus† Alligatoroidea Planocraniidae† Gavialoidea Crocodyloidea