Erythrosuchidae

Erythrosuchidae (meaning "red crocodiles") are a family of large basal archosauromorph carnivores that lived from the later Early Triassic (Olenekian) to the early Middle Triassic (Anisian). Their fossil remains are known so far from South Africa (Beaufort Group of the Karoo Basin), the Perm region of Russia, and China. They were the apex predators of their day, with lengths of 2.5 to over 5 meters. In the largest forms, such as Erythrosuchus, the skull alone can be a meter in length. The large contemporary Kannemeyeriid dicynodonts doubtless constituted much of their prey. However, the first Erythrosuchids appear in the fossil record slightly earlier than the Kannemeyeriids do, so it must be assumed that they also fed on other animals as well.

Erythrosuchidae were formerly classified as Thecodonts of the suborder Proterosuchia. This classification is no longer used by paleontologists, who now employ a cladistic approach. In this, Erythrosuchids constitute an Archosauriformes clade that is an outgroup to the Archosauria proper. The presence of certain Archosaurian features such as the triradiate pelvic girdle, the fourth trochanter, and the third metatarsal longer than the fourth, indicate that Erythrosuchids are closer to the true Archosaurs than the Proterosuchidae, which lack these features.

Thus the Erythrosuchidae occupy a transitional evolutionary position between the most primitive archisauriformes and more advanced Triassic archosaurs.