Homologous structures have the same embryonic origin and basic structure, though they mayor may not perform the same function. Homologous structures shows that the animal which possess them have commonancestoryandshowevolutionbydivergencefrom the ancestral type. Vestigial organs are those which have ceased to be any use to their possessor but still persist generation after generation in a reduced form. They are retrogressive organs but were well developed and functional in the ancestors.