Frogs, birds, rabbits and lizards all have differently shaped forelimbs, reflecting
their different lifestyles. But those different forelimbs all share the same set of
homologous bones the humerus, the radius, and the ulna. These same bones can
even be seen in fossils of the extinct lobe-finned fish, Eusthenopteron. Such homologies
reveal the common ancestry of all these animals.