Erythrosuchus

Extinct genus of reptiles

Erythrosuchus (from ἐρυθρός , 'red' and σοῦχος , 'crocodile') is an extinct genus of archosauriform reptiles from the Triassic of South Africa. Remains have been found from the Cynognathus Assemblage Zone of the Beaufort Group in the Karoo of South Africa. In the Late Triassic, the ecological niche left by Erythrosuchus was filled by archosaurs including Saurosuchus and Postosuchus.

Erythrosuchus is known from many specimens, most of which are fragmentary. The holotype, described by Robert Broom in 1905 and known as SAM 905, is poorly preserved. Only small pieces of the limbs, pectoral and pelvic girdles, skull, and a few vertebrae are present in this specimen. A thorough description of the genus was given by German paleontologist Friedrich von Huene in 1911. The fossil material that served as the basis for the description is now housed in the Natural History Museum in London. Like the holotype, it is very fragmentary, and some specimens may even belong to the same individual as SAM 905. One specimen, known as NHMUK PV R 3592, is relatively more complete, with much of the postcranial skeleton intact. This skull, known as BPI 5207 and currently part of the collection of the Bernard Price Institute for Palaeontological Research in South Africa, has a somewhat pointed snout. Earlier restorations may have shown a deeper snout because how the bones of the skull articulated with one another was unknown then. The braincase has also been studied, and possesses features that are shared with other early archosauriforms. Many of these characteristics are considered plesiomorphic, or ancestral, in archosaurs. While Erythrosuchus is not considered an archosaur, it is thought to be closely related to the last common ancestor of all archosaurs.

The hypothetical last common ancestor of archosaurs is thought to have shared many features with Erythrosuchus, many of which are found in the braincase. For example, the inner part of the otic capsule (the skeletal structure surrounding the inner ear) is not entirely ossified, or completely formed of bone. Neither is the channel for the perilymphatic duct, which is a tube that leaves the lagena. Erythrosuchus has a short lagena, which is also expected in the last common ancestor of all archosaurs.