[Campbell Biology P.786] Which of the following statements regarding turtle shell evolution ... | Practice Question
Which of the following statements regarding turtle shell evolution and head retraction is INCORRECT?
A: Early turtles like Pappochelys had a complete lower shell but an incomplete upper shell, indicating gradual shell development.
B: All turtles possess a boxlike shell formed by the fusion of upper and lower shields to their vertebrae, clavicles, and ribs.
C: Mechanisms for head retraction into the shell evolved independently in two separate lineages of turtles.
D: Sea turtles, such as leatherbacks, have a reduced shell and enlarged forelimbs adapted for swimming.
Explanation
Option A is incorrect because the text states that Pappochelys had "a series of hard, shell-like bones along its belly," but it was "another early turtle" not Pappochelys itself that had "a complete lower shell but an incomplete upper shell" by 220 million years ago.