Homology Provides Evidence for Evolution
1. Compare the picture of the limbs of the dolphin, shark, and wolf. Are the
bones inside the dolphin's flipper more similar to the wolf's leg are the sharks
fin? Justify your answer.
2. Compare the jaws of the wolf to those of the dolphin and the shark. Is the
structure of the wolf's jaw closer to the dolphin or the shark? Justify your
3. Look at the pictures of the three skulls (craniums). Which two skulls seem
the most similar. Justify your answer.
4. Draw the "correct" evolutionary tree showing the relationship between a wolf,
a dolphin, and a shark.
5. What living group do sharks, dolphins, and wolfs have in common (out-group)?
Add the out-group to the evolutionary tree you drew for question #4.
Bear, Opossum, Raccoon
6. Raccoons and opossums look alike but they actually belong to two different
groups of mammals: the placentals and the marsupials. Do bears belong to the
placenta or "pouch" group? Justify your answer.
7. Compare the newborn bear, opossum and raccoon for signs of physical maturity.
Which pair seems most closely related? Justify your answer.
8. Compare the DNA sequence of the bear, raccoon, and opossum. The pair that
shares the most sequences are the closest living relatives. Is the raccoon a
closer relative of the bear or the opossum? Use the DNA evidence to justify your
9. Draw the "correct" evolutionary tree showing the relationship between a bear,
opossum, and a raccoon. Include the echidna as the "out group".
10. What is one difference between the echidna and the other three animals?
Human, Tunicate, Sponge
11. Humans obviously have brains; does a tunicate have a brain? Does a sponge
have a brain?
12. What is a notochord? Which two species have notochords during their
13. Look at the picture of the developing human. What are two characteristics
that a developing human embryo has but that later disappear?
14. Compare the DNA sequence of the tunicate, sponge, and human. The pair that
shares the most sequences are the closest living relatives. Is the human a
closer relative of the tunicate or the sponge? Use the DNA evidence to justify