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Diapsida : Archosauromorpha : Archosauriformes : Archosauria : Pseudosuchia

Large dinosaur-like carnivores

Ornithosuchids, like the rauisuchians, were large, carnivorous pseudosuchians that superficially resembled theropod dinosaurs and they too lived in the Middle and Upper Triassic Period.

Ornithosuchids include Ornithosuchus from Scotland and Riojasuchus and Venaticosuchus from Argentina. They had large, blocky heads with deep, narrow faces and sharp teeth. Their hind legs were longer than their front legs and they were probably able to walk on either two legs or four — and again like rauisuchians, with their legs beneath their bodies, not out to the side. A row of bony scales ran down the middle of the back, just like those shown in some paintings of dinosaurs. All in all, ornithosuchids looked very much like theropod dinosaurs, and in fact they have sometimes been confused with theropods. But many details of their anatomy, such as their braincases and ankle joints, show that they were more closely related to crocodiles. This is another case of convergent evolution, in which different groups of animals evolve the same shape independently (see Phytosauria for another example of convergent evolution).

Restoration of the skeleton of Ornithosuchus

A restoration of the skeleton of Ornithosuchus.
Lateral and dorsal views of the skull of Ornithosuchus

Lateral and dorsal views of the skull of Ornithosuchus.


  • Benton, M.J. 2005. Vertebrate Palaeontology, 3rd Ed. Blackwell Publishing, Malden, MA. 455 pp.
  • Carroll, R.L. 1988. Vertebrate Paleontology and Evolution. W.H. Freeman and Company, New York. 698 pp.
  • Nesbitt, S.J., and Norell, M.A. 2006. Extreme convergence in the body plans of an early suchian (Archosauria) and ornithomimid dinosaurs (Theropoda). Proceedings of the Royal Society of London B, Biology Letters 273:1045-1048. DOI 10.1098/rspb.2005.3426

Text by Matt Wedel, 5/2007. Ornithosuchus images used with permission of the Royal Society of London: from Walker, A.D. 1964. Triassic reptiles from the Elgin area: Ornithosuchus and the origin of carnosaurs. Philosophical Transactions of the Royal Society of London, B 248:53-134.