Where do whales belong?

Although it is true that whales have flukes instead of hindlimbs this does not mean that whales do not belong in a monophyletic group of mammals that have hindlimbs. The reason being that early whales did in fact have legs. Even though they no longer possess these hindlimbs it does not take away from the fact that whales once did have them. Occasionally there are whales born with vestiges of these limbs. Whales losing their limbs is just one example of a dramatic evolutionary change, something that has happened countless of times to different species.