Characters and Anatomy


Dinosaurs all show some major modifications of the basic archosaurian skeleton.

Archosaurian skeleton
Skeleton of Postosuchus by P. Olsen, after Long and Murry (1996)

Primitive Dinosaurian Skeleton
Skeleton of Coelophysis bauri by P. Olsen, after Paul (1988)


Top set of hips on the left is the saurischian form, the bottom set on the left is the ornithischian form. The legs are from a theropod dinosaur (From Benton (2000)).

Dinosaurs are divided into two clades based upon hip structure: Saurischia and Ornithischia

  • Saurischian ("lizard hips") dinosaurs have a hip with the pubes pointing down and foward: includes Sauropodomorpha, and Theropoda
  • Ornithischian ("bird hips") dinosaurs have an enlarged hip girdle, and a backwards pointing pubes: includes Thyreophora, Ornithopoda, and Marginocephalia

Author: Emma Schachner
Last updated: 13 November 2004
Return to Fossil groups home page

Websites produced by students on the MSc Palaeobiology programme in the Department of Earth Sciences at the University of Bristol for academic year 2003-4