neosuchians

Neosuchia is a clade within Crocodylomorpha, a major group of archosauriforms that includes all crocodile relatives. Neosuchians are more derived than the earlier notosuchians and form the lineages that gave rise to most later crocodyliforms, including the true crocodilians. The definition is phylogenetic, based on common ancestry rather than a single shared trait.

Fossil record and diversity: Neosuchians first appear in the Early Jurassic and show extensive diversification through the Jurassic and Cretaceous, with a wide geographic distribution. They occupied a broad range of habitats, from freshwater rivers and lakes to marine environments. The group includes both small terrestrial species and large aquatic forms, many of which became efficient ambush predators.

Relationship to living species: The crown group Crocodylia (crocodilians) is nested within Neosuchia, meaning modern alligators, crocodiles, and gharials are neosuchians. Within Neosuchia, numerous extinct lineages arose, including the long-snouted marine forms.

Significance: Studying neosuchians helps illuminate the evolution of crocodilian biology, including features related to diet, ecology, and the transition to fully aquatic life in some lineages.