The Archosaurs were the dominant reptiles of the Mesozoic, the Age of Reptiles.
Primitive archosaurs were bipedal and had a lightly built, diapsid skull with a
bony sclerotic ring around the eye and an antorbital fenestra in front of the eye.
Archosaur orders include the primitive Thecodontia, the Crocodilia, the Pterosauria,
and the two dinosaur orders Saurischia and Ornithischia. Saurischian dinosaurs had
a triradiate pelvis with the pubic bone directed forward; ornithischian dinosaurs had
a tetraradiate pelvis in which part of the pubis projected to the rear, paralleling the ischium.
- Archosaur traits:
- Diapsid skull roof
- Early tendency to bipedalism
- Sclerotic ring in eye
- Antorbital fenestra
- Order Thecodontia
- Order Crocodilia
- Order Pterosauria
- Order Saurischia
- Order Ornithischia
- Ornithopoda
- Pachycephalosauria
- Scelidosauridae
- Stegosauria
- Ankylosauria
- Ceratopsia
- Were dinosaurs warm-blooded?
- High stance
- Large size
- Predator/prey ratios
- Feathers in some
- Bone histology: wide-open blood spaces
Illustrations
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