Cussion Questions Continued

seemingly were flightless? Moreover, what were possible additional functions of feathers for those theropods that were arboreal gliders or flyers?

4. Using the list of characters for Herrerasauridae listed in the chapter, compare it with those for the hypothetical ancestral dinosaur listed in Chapter 6. In what characters do they overlap and in which ones do they differ? Give an explanation for why some should differ and how they might reflect evolutionary processes.

5. Using the lists of characters in the chapter, compare Herrerasauridae versus Ceratosauria and Ceratosauria versus Tetanurae. Once again, give an explanation for why some characters should differ and how they might reflect evolutionary processes.

6. Explain the difference between a stem-based clade and a node-based clade, using theropods as examples. What new fossil finds for each clade could cause these classifications to change?

7. Compare and contrast the skeletal foot of Tyrannosaurus rex with its probable footprint in Figure 9.11. What aspects of soft-part anatomy for the foot are most obvious in the footprint that otherwise would not be evident in the skeletal foot? How could this information relate to the possible walking or running speeds of Tyrannosaurus?

8. Given three theropod trackways with the following estimated speeds, calculate the momentum for each respective theropod using their hypothetical masses:

9. Using the characteristics of eggs, nests, and skeletal data from Troodon and Oviraptor, how could you develop a model for identifying egg clutches for other theropods without having identifiable embryonic remains? Develop a list of characteristics that would help in such identification.

10. What evidence would you need to support the following alternative hypotheses used to explain the close proximity of four specimens of Deinonychus with one specimen of Tenontosaurus? Think about both body and trace fossil evidence that would need to be present to make it more convincing.

a. The Deinonychus specimens were traveling together as a group, and drowned in a stream. Their bodies were washed into the same location as a dead Tenontosaurus, and then scavengers ate from all five carcasses.

b. One pack of Deinonychus attacked and killed the Tenontosaurus, but a rival pack entered the area and fought the first pack, causing the deaths of members from each pack.

c. Scenario B occurred, but the two packs consisted of two families traveling as groups.

d. The Tenontosaurus specimen was traveling with a herd, but it was separated from the herd by a pack of Deinonychus, which then hunted it down and killed it.

e. The Tenontosaurus specimen died from an infection, then a Deinonychus pack scavenged the corpse and several died from eating the toxic meat.

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