Answer:
A dolphin's flipper, a bird's wing, a cat's leg, and a human arm are considered homologous structures. ... This structure serves as evidence of having a common ancestor, one that would have had a tail. All mammals share the homologous structure of the vertebrae in common. Homologous structures share a similar embryonic origin; analogous organs have a similar function. For example, the bones in the front flipper of a whale are homologous to the bones in the human arm.
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