Orthosuchus

Orthosuchus is an extinct genus of early crocodyliform reptiles that lived during the Triassic period. Fossils have been found in southern Africa, notably in rocks of the Karoo Basin associated with the Stormberg Group. The genus name combines Greek orthos, meaning straight, with suchus, meaning crocodile, a reference to its relatively straight snout compared with later crocodilians. The type species is Orthosuchus stormbergensis, known from fragmentary skull and postcranial remains.

Orthosuchus was a small-bodied animal, with estimates placing its length at roughly half a meter to under a meter. It possessed an elongated, slender skull with conical teeth suitable for catching small vertebrate prey. Limbs were relatively short, suggesting a primarily terrestrial or possibly semi-aquatic lifestyle rather than a highly aquatic one.

In terms of classification, Orthosuchus is regarded as an early or basal crocodyliform, a member of the crocodile-line of archosaurs. Its placement has varied with different analyses, but it is generally cited as helping to illuminate the early diversification of crocodyliforms during the Triassic.

Paleobiology and ecology are inferred from its morphology and the deposits where it was found. Orthosuchus likely occupied a small predator niche within Triassic floodplain ecosystems that also housed other archosauriforms and wildlife. The genus contributes to our understanding of the early evolution of crocodyliform features prior to the rise of larger, more derived crocodilians.