Homologous structures are anatomical features in different organisms that have similar origins but may serve different functions. A classic example of homologous structures is the forelimbs of vertebrates. For instance, the forelimbs of humans, whales, bats, and birds all share a similar skeletal structure.
Despite their different functions—humans use their arms for manipulation, whales use their flippers for swimming, bats for flying, and birds for perching—the underlying bone structure remains markedly similar. This similarity indicates a common evolutionary ancestor, showcasing how different species can adapt their anatomical features for various environments or activities while retaining a basic structural framework.