Critical Thinking Questions
23. What are the characteristic features of the chordates?
24. What is the structural advantage of the notochord in the human embryo? Be sure to compare the notochord with the corresponding structure in adults.
25. What can be inferred about the evolution of the cranium and vertebral column from examining hagfishes and lampreys?
26. Why did gnathostomes replace most agnathans?
27. Explain why frogs are restricted to a moist environment.
28. Describe the differences between the larval and adult stages of frogs.
29. Describe how metamorphosis changes the structures involved in gas exchange over the life cycle of animals in the clade Anura, and what evolutionary advantage this change provides.
30. Describe the functions of the three extra-embryonic membranes present in amniotic eggs.
31. What characteristics differentiate lizards and snakes?
32. Based on how reptiles thermoregulate, which climates would you predict to have the highest reptile population density, and why?
33. Explain why birds are thought to have evolved from theropod dinosaurs.
34. Describe three skeletal adaptations that allow for flight in birds.
35. How would the chest structure differ between ostriches, penguins, and terns?
36. Describe three unique features of the mammalian skeletal system.
37. Describe three characteristics of the mammalian brain that differ from other vertebrates.
38. How did the evolution of jaw musculature allow mammals to spread?
39. How did archaic Homo sapiens differ from anatomically modern humans?
40. Why is it so difficult to determine the sequence of hominin ancestors that have led to modern Homo sapiens?