1. Why do you suppose the eastern and Western North American dinosaurs are diffe
ID: 295144 • Letter: 1
Question
1. Why do you suppose the eastern and Western North American dinosaurs are different as to species and diversity?
2. What are the main groups of Alabama dinosaurs and what is their relationships to one another in the food chain?
3. Why do you suppose that Alabama dinosaur fossils are not found where these animals lived?
4. During what span of time did Alabama dinosaurs (the ones we know from the fossil record) live?
5. What factors may have affected the distribution of the number of fossil finds per state in the eastern U.S.?
Explanation / Answer
Answer:
1. The western North America which was once a part of Laramidia, the inland continent, was affected broadly by arid climate. Dinosaur fossils are abundant and show high diversity in all three dinosaur ages. The reason is that, the eastern part was filled by seawater for a long period of time in the Mesozoic because of Pangea break-up. And as dinosaurs were mostly terrestrial animals, diverse range was not found. Whereas, in western part, sedimentation was at a high rate, which enhance well preservation of dinosaur fossils in freshwater and near-shore facies.
2. The main groups of dinosaurs found in Alabama were Ankylosauria (armored body) and Hadrosauria (duck-billed) of Ornithischia order and also Tyrannosauroids. The first two group were herbivores which fed on leaves. Tyrannosauroids were carnivores which must have been fed on these herbivore groups.
3. In the Triassic, Alabama experienced rifting triggered by Pangea break-up. So, as a consequence, Jurassic Alabama was filled with seawater. So, in most part of Mesozoic Alabama experienced marine environment. So, no significant diversity occured in the range of dinosaur species. Moreover, in the eastern part, abundant rainfall gives rise to intense egetation which halts erosion of topsoil. That is why, most of the exosures of sedimentary layers got buried which claims the dinosaur fossils.
4. The Alabama dinosaurs lived mostly from Late Jurassic to Late Cretaceous period, as evident from fossil records.
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