These are physical features shared by organisms with common ancestry; they may have the same structure, but different functions developmentally mature organisms.

Homologous structures

Homologous structures are physical features that can be found in very different animals, indicating that the organisms seem to be related or descent from a common ancestor. Homologous structures may have similar functions or form in different organisms. An example is the human eyes which are homologous to the eye bulbs located on the heads of blind creatures that reside in caves.

he forelimbs below belong to four species that descended in a direct line from the ancestral mammal shown above. of the four descendants shown, which species most likely appeared earliest in evolutionary history?