The story
Archosaurs split in the Triassic into two lines: the bird line, which includes dinosaurs and pterosaurs, and the crocodile line, which then included rauisuchians, aetosaurs and phytosaurs. The earliest crocodylomorphs, such as Carnufex from North Carolina (named in 2015, about 3 m long) and the later Terrestrisuchus and Saltoposuchus, appear in the Late Triassic. They are small to medium, slender, long-legged hunters that run on land, quite unlike the sprawling swimming crocodiles of today.
Most other crocodile-line archosaurs died out at the end-Triassic extinction, leaving crocodylomorphs to spread. In the Jurassic some turned to the sea, such as the paddle-limbed metriorhynchids; in the Cretaceous came giants like Sarcosuchus from Niger, found by Paul Sereno, reaching about 11 to 12 m, and Deinosuchus from North America. The modern group Crocodylia arose in the Late Cretaceous and passed through the asteroid extinction essentially intact.
Why it mattered
- Their survival of the end-Triassic extinction set up the dinosaurs' dominance of the Jurassic.
- Crocodylomorphs gave rise to the crocodilians, the closest living relatives of birds.
- They show how one body plan can change from a fast land runner into an ambush predator in water.
Community notes
Loading notes…