INTEGBI N33 Lecture Notes - Lecture 16: Thyreophora, Ornithischia, Stegosauria
31 Mar 2018
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Document Summary
Primitive small bipedal ornithischian with canine-like teeth, likely used for display since it exhibits sexual dimorphism. Had sharp canines in front of mouth and molars in back for processing food. One of 3 main groups of ornithischians, evolved towards heavy body armour. Bony scutes (spikes) on skin for protection. Modified osteoderms, likely originally evolved for protection but could have later had function in display and thermoregulation; Some stegos have vascularized plates, which are likely just for display and thermoregulation; Diversity in shapes of plates between species also indicates display and species recognition. Tall neural arches with highly angled transverse processes. For attaching muscles to support heavy plates on back. Plates are not solid bone; makes them lighter and easier to carry. Huge disparity between length of back legs and front legs so likely low-browsing animals. May have been able to rear up on back legs. Enlargement of sacrum, likely for storing sugars, which is found in some modern birds.
