Biology 11th Edition by Gerald Audesirk,Teresa Audesirk,Bruce Byers

Exercise 3

The flipper of a seal is homologous with the ______________ of a bird, and both of these are homologous with the ______________ of a human. The wing of a bird and the wing of a butterfly are described as ______________ structures that arose as a result of ______________ evolution. Remnants of structures in animals that have no use for them, such as the small hind leg bones of whales, are described as ______________ structures.