|Saurischian hip (Tyrannosaurus rex): (A) Ischium (B) Ilium (C) Pubis|
Examples of Saurischians
|Tyrannosaurus rex: Note that the manus is more than 45% the length of the humerus and radius combined, as well as the distinctly asymmetrical manus, with Digit II being dominant.|
|Ornithischian hip (Triceratops horridis): (A) Pubis (B) Ilium (C) Ischium|
Examples of Ornithischians
|L to R: Edmontosaurus, Parasaurolophus, Corythosaurus. All display the Diapsid condition. The reason these dinosaurs are all placed in to Ornithischia is because they either have very reduced or no antorbital fenestra.|
While at the museum, we were able to put our knowledge concerning temporal fenestration to the test. The synapsid condition was apparent in the mammal skeletons, and the diapsid or modified diapsid condition was present in the dinosaur skulls.
|L to R: Irish elk, saber-toothed cat, wooly mammoth|
Dimetrodon limbatus is a basal synapsid, not a dinosaur. This creature is on the lineage that lead to modern mammals. Therefore, D. limbatus was more closely related to mammals than to dinosaurs.
|Dimetrodon limbatus. Note the synapsid condition of the skull.|
The tuatara, Sphenodon punctatus, today displays the best example of the diapsid condition. Endemic to New Zealand, there are only two species still around today.