01:460:206 Lecture Notes - Lecture 11: Thagomizer, Stegosauria, Predentary
9 Sep 2019
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Paleozoic land ecology: seed ferns, cycads, conifers, carboniferous land floras. Evolution of angiosperms: flower plants, beginning of cretaceous period, new plants, new plan eaters (ornithopods) Order ornithiscia: bird like pelvis, predentary bone, bone tilted backwards allowed larger stomach for digestion, evolved from forward facing pubis. Theyreophora shield bearers : stegosauria plated reptile , anklosauria fused reptile , dermal bone armor plates, armored plates called scutes or esteoderms (skin bones, not connected to bone float in skin. Price of defense: speed not enough to protect them, more armor weighs animal down, obligatory quadrupedal, bodies low to ground, ate low vegetation. Thagomizer: tail spikes, spikes attached to side and faced outward, a lot of pictures show spikes pointing upward, tail not very flexible, no more than two pairs of spikes. Active defense: used plates and spikes, thagomizers show damage, rather than passive defense.
