1. Define: Chordata, notochord, gnathostome, Sarcopterygii, skull, mandible, girdles, neural arch, centrum, process, ilium, ischium, pubis, acetabulum, sternum, humerus, femur, radius, ulna, tibia, fibula, phatanges, ungual, metacarpals, metatarsals, metapodials, occipital condyle, foramen magnum, stapes, skull roof, tympanic membrane, nares, orbit, palate, amniote, anamniote, amnion, anapsid, synapsid, diapsid, upper temporal fenestra, lower temporal fenestra, archosaur, Archosauromorpha, lepidosaur, Crurotarsi, Ornithodira, Dinosauria, pterosaur, mesotarsal, Ornithischia, Saurischia.
2. Explain the importance of the amnion in the evolution of terrestrial tetrapods.
3. Describe the basic structure of the vertebrate limb.
4. Draw a skull and lower jaws, indicating the skull roof, braincase, temporal region, orbit, nares, and snout.
5. For how long have the mammal and bird lineages been evolving separately?
6. Why is it that we said that a bird was more closely related to a crocodile than a crocodile is to a lizard?
8. Construct a cladogram with just Dinosauria, Ornithischia, Archosauria, and Crocodylia marked on it.
9. How can birds be reptiles?
10. Within Amniota, warm-bloodedness and flight occur in bats, in birds, and in pterosaurs. Use a cladogram to show how many separate evolutionary events this required.
Ornithischia: armored, horned, and duck-billed dinosaurs
In the preceding chapter we met Ornithischia, one of the two great branches of dinosaurs. Although it was identified as early as 1887, nobody at that time had an inkling how diverse the group really was. Since then, we have learned about the richness of ornithischians as well as about the anatomy, evolution, and even behavior of these dinosaurs. We'll check out orni-thischians in Chapters 5-7. But first, let's introduce Ornithischia a bit more completely.
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