Evidence of Evolution

AP Biology· difficulty 1/5

vestigial pelvic bone Whale skeleton (schematic)

Why does a whale possess vestigial pelvic bones?

  • A

    Vestigial bones are evidence against common ancestry

  • B

    Whales evolved from terrestrial tetrapod ancestors that had functional pelvises

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  • C

    Whales developed pelvic bones de novo from selection pressure

  • D

    The bones serve a primary structural role in swimming

Explanation

Vestigial structures are remnants of features that were functional in ancestors. Cetacean ancestors were terrestrial mammals with hind limbs and pelvises; whales today retain reduced, non-functional pelvic bones as evidence of that ancestry.

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