The Origin and Evolution of Vertebrates

1. Chapter 34 The Origin and Evolution of Vertebrates Questions prepared by Ruth BuskirkUniversity of Texas at Austin Michael DiniTexas Tech University

2. Why are tunicates thought to be more closely related to vertebrates than are the other invertebrate chordates? • They share the same 13 chordate Hox genes. • They have genes associated with a heart and thyroid gland. • They have pharyngeal slits, unlike the other invertebrate chordates. • They have a notochord, unlike the other invertebrate chordates. • They are larger in size than other invertebrate chordates.

3. Why are humans considered members of the chordates when we have no notochord, pharyngeal slits, or muscular, post-anal tail? • Our mammalian ancestors show some of these traits. • Other similar traits appear in humans. • Our nerve cord has replaced the notochord. • These traits are only found in invertebrate chordates. • These chordate traits appear in human embryos.

4. Which of the following traits is shared by all vertebrates, at least in some developmental stages, except the lampreys? • notochord • vertebrae • cartilaginous skeleton • cranium (head) • mouth with jaws

5. Members of the bony fish clade (Osteichthyes) are very diverse. Of the following pairs, which does not represent two classification subgroups within the Osteichthyes clade? • ray-finned fishes and lobe-finned fishes • lungfishes and coelocanths • lungfishes and tetrapods • freshwater fishes and saltwater fishes

6. When early systematists distinguished Chondrichthyes (cartilaginous fish) from Osteichthyes (bony fish), it was not clear exactly when bony skeletons first appeared in the vertebrates. Which of these suggests that a reduction of bone in Chondrichthyes is a derived condition that emerged after the origin of bony skeletons? • All fish except Agnatha have jaws. • Chondrichthyes and Osteichthyes have paired fins and lateral lines. • Traces of bone tissue are found in living and fossil Chondrichthyes. • The cartilage skeleton of Chondrichthyes is impregnated with calcium. • Chondrichthyes do not have swim bladders, as do many Osteichthyes.

7. Most amphibians undergo metamorphosis from an aquatic larva to a more terrestrial adult. Which of the following is not part of that metamorphosis? • finned tail  legs • lateral line  eardrum • gills  lungs • aquatic food  terrestrial food • smooth skin  scaly skin

8. Which of the following is not a new adaptation of birds that supports flight? • feathers of wings and tail • four-chambered heart and efficient lungs • keratinized beak in place of mineralized teeth • amniotic egg • single ovary in females

9. Which of these correctly describes phylogenetic relationships among birds, mammals, and reptiles? • Birds share the closest common ancestor with dinosaurs. • Reptiles and birds, but not mammals, are amniotes. • Mammals evolved from therapsid reptiles after the fall of the dinosaurs. • Birds and mammals are more closely related to each other than either group is to crocodilian reptiles. • Among living species in the group we call reptiles, turtles and snakes are most closely related to each other.

10. All of the following are correct matches for the name of a taxonomic group containing humans and some distinguishing characteristics of that group except • genus Homo: short jaw, large brain • hominin (“hominid”) family of genera: upright posture, bipedal locomotion • order Primates: grasping thumbs, forward-facing eyes • class Mammalia: placenta joining fetus and mother, development entirely within uterus • species sapiens: slender body, lack of heavy brow ridge, cave paintings