Question

question 19 of 20 : select the best answer for the question. 19. according to the cladogram shown, which two animal species shared the most recent common ancestor?
a. sharks and birds
b. birds and rodents
c. primates and crocodiles
d. birds and crocodiles
mark for review (will be highlighted on the review page)

Explanation:

To determine which two species share the most recent common ancestor, we analyze the cladogram. The most recent common ancestor is indicated by the closest node (branch point) connecting two species.

• For option A: Sharks and birds have a very distant common ancestor (near the "Vertebrae" node), so they don't share a recent one.
• For option B: Birds and rodents have nodes that are not as close as others. Rodents are grouped with primates, and birds with crocodiles.
• For option C: Primates and crocodiles have a relatively distant common ancestor (above the "Amniotic egg" node but not close).
• For option D: Birds and crocodiles share a common node (the one labeled before "Eggs with shells" and after the "Amniotic egg" - this node is closer than the nodes for the other options, meaning their common ancestor is more recent.

Answer:

D. Birds and crocodiles