Final answer:
Homologous structures are structural similarities shared by a wide array of distantly related species that are inherited from a remote ancestor.
Step-by-step explanation:
Homologous structures are structural similarities shared by a wide array of distantly related species that are inherited from a remote ancestor. These structures may have different functions in the descendants but have the same basic pattern of bones. For example, the forelimbs of humans, bats, whales, and dogs have homologous structures, despite the differences in their functions.
These similarities, such as the number of bones in the forelimb, indicate a common ancestry and are the result of divergent evolution.