Pseudosuchia

Pseudosuchia is a major clade within Archosauria that encompasses the crocodile line of archosaurs and their extinct relatives. The name, meaning "false crocodiles," reflects its position as the crocodile lineage within Archosauria. In contemporary phylogenetics, Pseudosuchia is defined as all archosaurs more closely related to Crocodylia (crocodilians) than to Aves (birds), with Ornithodira (the bird-line) forming the sister clade to Pseudosuchia within Archosauria.

The clade is diverse, including Crocodylomorpha, which contains crocodilians and their extinct relatives, and other pseudosuchian groups such as Suchia, which comprises various Triassic lineages like rauisuchians and aetosaurs. These groups ranged from armored, herbivorous forms to large terrestrial carnivores, illustrating a wide array of ecological roles during the Triassic.

The fossil record indicates that pseudosuchians first appear in the late Permian to early Triassic, rapidly diversify during the Triassic period, and subsequently decline in many lineages by the Jurassic. Despite this turnover, Crocodylomorpha survived and eventually gave rise to modern crocodilians, the only living representatives of Pseudosuchia.

In classification, Pseudosuchia is treated as a phylogenetic group defined by relationships to Crocodylia rather than by a single shared diagnostic trait. As such, the group reflects evolutionary relationships within Archosauria, contrasting with the bird-line lineage of Ornithodira and its diverse descendants.