Erythrosuchidae

Erythrosuchidae (meaning "red crocodiles" in Greek) are a family of large basal archosauriform carnivores that lived from the later Early Triassic (Olenekian) to the early Middle Triassic (Anisian). The family Erythrosuchidae was named by David Meredith Seares Watson in 1917. They were the apex predators of their day, with lengths of to almost . Their fossil remains are known to date from South Africa (Beaufort Group of the Karoo Basin), China, India and European Russia, from the Early to Middle Triassic. Erythrosuchids were unusually large and robust archosauromorphs. Several features set them apart from other archosauriformes and are also seen in later, more derived archosaurs. For example, they lack teeth on the palate, which are found in other early archosauriformes, such as Doswellia and euparkeriids. In erythrosuchids, the centra (central parts of vertebrae) are deeply indented on either side, differing considerably from the usual cylindrical shape of the centra in early archosauriformes, but similar to later archosaurs. The heads of erythrosuchids are generally disproportionately large and deep. In all erythrosuchids, the lower margin of the premaxilla, the bone at the tip of the upper jaw, is lower than the lower margin of the maxilla, the bone behind the premaxilla. This forms a characteristic "step" that makes erythrosuchids easily distinguishable from all other early archosauriformes, which have smooth jaw margins that are either straight or gradually curved. Erythrosuchids are notable for being the first archosauriforms to have a triradiate pelvic girdle with three projecting areas formed from three bones: an ilium and an elongated pubis and ischium. Although it is small, the fourth trochanter, a ridge on the femur that serves as a muscle attachment in archosaurs, first appears in erythrosuchids. The triradiate pelvis and fourth trochanter are both features which indicate that erythrosuchids had an erect stance similar to later archosaurs. More basal archosauriforms such as proterosuchids lacked these features and probably had a more sprawling posture.