Although Ambulocetus looked like a furry crocodile or a giant otter, it was actually an early whale. Its back legs in particular seemed to be used for propulsion, and its feet had long, probably webbed toes (each ending in a tiny hooflet). Ambulocetus was not as agile in the water as an otter and seems to be adapted for ambushing large prey which it then drowned. Its skull shows adaptations for holding large, struggling prey underwater. Its ear bones also show that it did not have external ears but instead used the same method of hearing as modern whales - picking up vibrations through the jawbone. One fairly complete specimen and several partial skeletons have been found in Pakistan.

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