Fossils offer crucial clues for evolution, because they reveal the often remarkable forms of creatures long vanished from Earth
... numerous fossils from the first ten million years or so of whale evolution. These include several fossils of aquatic creatures such as Ambulocetus and Pakicetus, which have characteristics now seen only in whales — especially in their ear anatomy — but also have limbs like those of the land-living mammals from which they are clearly derived. Technically, these hybrid creatures were already whales. What was missing was the start of the story: the land-living creatures from which whales eventually evolved.
