Temporal range: Late Triassic Carnian
Ornithosuchus (meaning "bird crocodile") is an extinct genus of crurotarsan from the Late Triassic (Carnian) Lossiemouth Sandstone of Scotland. It was originally thought to be the ancestor to the carnosaur dinosaurs (which then included Tyrannosaurus). However, it is now known to be more closely related to crocodilians than to dinosaurs.
Despite this relationship to crocodiles, Ornithosuchus was able to walk on its hind legs, like many dinosaurs. However, it probably spent most of its time on all fours, only moving bipedally when it needed to run rapidly. Its skull also resembled those of theropod dinosaurs, but more primitive features included the presence of five toes on each foot and a double row of armoured plates along the animal's back. Ornithosuchus was around 4 metres (13 ft) in length. Ornithosuchus looked like theropods, but it was not a dinosaur. It had five toes on each hind foot while Tyrannosaurus had only three.
A single species of Ornithosuchus has been described, the type species, O. longidens. Ornithosuchus is the type genus of the Ornithosuchidae, a family of facultatively biped carnivores that were geographically widespread during the Late Triassic. Two other genera are currently known, Venaticosuchus and Riojasuchus.
- Walker, A.D. (1964). "Triassic reptiles from the Elgin area: Ornithosuchus and the origin of carnosaurs". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 248(744): 53-134.