Despite Pseudosuchia meaning "false crocodiles", the name is a misnomer as true crocodilians are now defined as a subset of the group.

Crocodylomorphs themselves evolved a diverse array of lifestyles during the Jurassic and Cretaceous periods, although living pseudosuchians only include crocodiles, alligators, caimans, and gavialids.

The name Pseudosuchia was originally given to a group of superficially crocodile-like prehistoric reptiles from the Triassic period, but fell out of use in the late 20th century, especially after the name Crurotarsi was established in 1990 to label the clade (evolutionary grouping) of archosaurs encompassing most reptiles previously identified as pseudosuchians.

The name Pseudosuchia was coined by Karl Alfred von Zittel in 1887–1890 to include three taxa (two aetosaurs and Dyoplax) that were superficially crocodilian-like, but were not actually crocodilian.

Colbert considered small, lightly built archosaurs, such as Ornithosuchus and Hesperosuchus—both of which were at the time reconstructed as theropod dinosaur-like bipeds—to be typical pseudosuchians.

A different definition was suggested by Benton and Clark, 1988: the node-based taxon including the last common ancestor of Rauisuchidae and aetosaurs and all of its descendants.

Benton and Clark also named a group called Crocodylotarsi, which includes most taxa now considered pseudosuchians.

However, Sereno defined Crurotarsi as a node-based clade, relying on the inclusion of groups such as Phytosauria, Aetosauria, and Crocodylomorpha.

For many years, Pseudosuchia and Crurotarsi have been considered partial synonyms because the latter clade encompasses all crocodilian-line archosaurs in most phylogenetic analyses.

The skull is often massively built, especially in contrast to ornithodires; the snout is narrow and tends to be elongated, the neck is short and strong, and the limb posture ranges from a typical reptilian sprawl to an erect stance like those of dinosaurs or mammals, although achieving it a different way.

Their heyday was the Late Triassic, during which time their ranks included erect-limbed rauisuchians, herbivorous armored aetosaurs, the large predatory poposaurs, the small agile sphenosuchian crocodilians, and a few other assorted groups.

A study published in 2010 postulates that there is significant evidence that volcanic eruptions changed the climate, causing a mass extinction that wiped out the dinosaurs' main competitors.

While dinosaurs were the dominant animals on land, the crocodiles flourished in rivers, swamps, and the oceans, with far greater diversity than they have today.

[4] †Proterosuchidae †Erythrosuchus †Vancleavea †Proterochampsia †Euparkeria †Phytosauria Avemetatarsalia (bird-lineage of archosaurs) †Ornithosuchidae †Gracilisuchus †Turfanosuchus †Revueltosaurus †Aetosauria †Ticinosuchus †Poposauroidea †Prestosuchus †Saurosuchus †Batrachotomus †Fasolasuchus †Rauisuchidae Crocodylomorpha The following cladogram is from a slightly older study, Brusatte, Benton, Desojo and Langer (2010).