Anatomical evolution mainly focuses on similarities and differences in the body structures of different species. The study of comparative anatomy forms the basics for modern study of evolution. Organisms with similar structures must have common ancestor which serves the subject for determining the relatedness of species. When species have same structure but different functions according to their needs and adaptions, this process is called Divergent Evolution and structures are homologous (Common Ancestry). Examples-  Vertebrate hearts or brains, All mammals share similarity in their forelimbs. When species have different structure but similar functions according to their environmental changes and adaptations, this process is called Convergent Evolution and structures are analogous (Different Ancestry). Examples-  Wings of insects, birds, bats