In land mammals, the pelvic girdle is the point where the leg bones attach to the rest of the skeleton. whales also have a small pelvic girdle. what type of evidence for common descent would include the whale's pelvic girdle?

comparative anatomy

Explanation:Darwin   proposed that the forelimbs of human, bats and other creatures (whale) are similar.  Although these Fore limbs are used for different purposes; he reasoned that similar forelimbs must have the same origin(Anatomy). He therefore concluded that these organisms should share same ancestors for evolution of modern Organism forms. He reasoned further that these modifications in body structures are required adaptations for survival in the competitive environment –survival of the fittest.  

Charles Darwin was an evolutionist, a biologist of immense knowledge. He formulated the law of survival of the fittest