Homologous Structures

A dog's paw and a human's hand have similar bone structure.

Homologous structures are anatomical similarities shared between species that indicate a common ancestor. Some homologous structures are not functional or are naturally lost throughout development. Homology is the opposite of analogy, where although the structures or abilities of the organisms are similar, they have evolved separately from their common ancestors to a point where they are unrelated. Examples: humans, dogs, birds, and whales all have similar skeletal structure of the forelimbs.