Whales are mammals rather than fish, yet they live in the word's oceans rather than on land. Because of the fact that they are mammals, scientists have believed for quite sometimes that whales are descendants of land mammals.
Some interesting evidence to support this theory has recently been found. In Egypt, fossils have been found of a forty-million-year-old whale leg, kneecap ankle, footbones, and toes. It appears from the fossil evidence that bones were not very strong and not very in comparison to the size of the whale.
Bases on this fossil evidence, the following evolutionary path has been hypothesized. As the whale began its evolution toward the water,its legs weakened and decreased in size. Then, during its millions of years in the water, the legs slowly disappeared, leaving only the front flippers today.