What is "rauisuchia"

"Rauisuchia" is a group of mostly large (often ) Triassic archosaurs. It belongs to a larger clade called Pseudosuchia. "Rauisuchia" is currently considered an evolutionary grade, or even a wastebin taxon. It includes most pseudosuchians that lived during the Triassic Period. Since crocodylomorphs likely originated from an ancestor that would have been a rauisuchian, Rauisuchia in its traditional sense is considered paraphyletic as it excludes crocodylomorphs. To designate it as an informal group in scientific literature, the name in its traditional sense is often enclosed in quotation marks.

Rauisuchians had an erect gait with their legs oriented beneath the body rather than sprawling outward. This type of gait is also seen in dinosaurs, but evolved independently in the two groups. In dinosaurs, the hip socket faces outward and the femur (thigh bone) connects to the side of the hip; while in rauisuchians, the hip socket faces downward to form a shelf of bone under which the femur connects. This has been referred to as the pillar-erect posture.

Rauisuchians lived throughout most of the Triassic. Along with many other large archosaurs, the group died out in the Triassic-Jurassic extinction event. After their extinction, theropod dinosaurs were able to emerge as the sole large terrestrial predators. The footprints of meat-eating dinosaurs suddenly increase in size at the start of the Jurassic, when rauisuchians are absent.