Earth Sciences 2266F/G Lecture Notes - Lecture 21: Sacrum, Lambeosaurus, Ornithopod
26 Jul 2016
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Much less armoured except they grow horns but most of them have no defense mechanism at all, vulnerable to predation. Their best defense is that they can run they rely on passive defense. All the features that are typical of ornithischian dinosaurs weren"t evolved at the same time. Predentary bone eventually evolved into pseudo-beak structure evolved early in the evolution of this group. Also sacral vertebral segments that link with ileum that links with pelvic girdle are evolved early; sacrals fuse together to support fast running of hind legs have to have good connection between legs and body. Ossified tendon, and tooth row were developed around the same time; tooth row for chewing to process vegetation in the mouth almost like mammals. Start to develop enamel too to make them better processors of vegetation. Stegosaurs have tiny skulls so probably not very smart. During the jurassic time, allosaurus was the largest predator, and stegosaurs walking around.
