<u>Transition fossils show</u><u> the presence of leglike structures, pointing to the possibility that the ancestors of </u><u>whale</u><u> and dolphins once lived on land.</u>
The cetaceans, which include whales, dolphins, and porpoises, are descended from land-dwelling mammals.
Traces of their terrestrial ancestry can still be seen in the bones of their fins, which resemble enormous, jointed hands, in their vertical spine movement, and in the fact that they must breathe air from the surface.
What is evidence that whales evolved from land mammals?
There are several indications from a whale's anatomy and biology indicating they originated on land.
They have paddle-shaped flippers that house hand bones with five "fingers," breathe air, and nurse their young with their own milk.
Whales have tiny back limbs as embryos, but these vanish before birth.
