Rauisuchian

Rauisuchian is a collective informal term used by paleontologists to refer to a group of large, predatory, herbivorous, and omnivorous reptiles that lived during the Triassic period. These animals were not dinosaurs, though they were closely related and were the dominant terrestrial predators before the rise of the dinosaurs. Rauisuchians were part of the larger group called pseudosuchians, which also includes crocodilians and their extinct relatives.

The term "rauisuchian" itself is derived from the genus Rauisuchus, named after the German paleontologist Christian Erich Hermann von Raumer. However, this grouping is paraphyletic, meaning it includes a common ancestor but not all of its descendants. Modern classifications tend to avoid paraphyletic groups, and the animals once referred to as rauisuchians are now typically placed within various clades of the larger pseudosuchian radiation, such as the Rauisuchia order, which itself is part of the crurotarsan archosaurs.

These animals were characterized by a robust build, a long tail, and powerful limbs. Many possessed armor in the form of bony plates called osteoderms. Their diets varied, with some being formidable carnivores that preyed on other reptiles and early mammals, while others were likely herbivores or omnivores. Rauisuchians exhibited a wide range of sizes, with some reaching lengths of over 6 meters (20 feet). They played a crucial role in Triassic ecosystems, occupying ecological niches that would later be filled by dinosaurs. Their extinction at the end of the Triassic allowed dinosaurs to diversify and become the dominant land vertebrates of the Jurassic and Cretaceous periods.