Ambulocetus quite literally means “walking whale”, and rightfully so as the ancient mammal is the suggested ancestor to the whales. Living around 50 million years ago, Ambulocetus was one of the biggest animals of its time, and one of the biggest successes. Ambulocetus had an immense advantage being able to walk on land and being an excellent swimmer. 
The hunting techniques of this primitive whale were not unlike modern crocodiles, submerging itself under the water of river banks and shorelines waiting for an unsuspecting animal to approach for a drink, then pouncing with a bone crushing bite. Once prey was locked in its jaws, Ambulocetus would pull it into the water and drown it. 

Despite its appearance, Ambulocetus was already well on the way to evolving for permanent underwater living. The shape of the skull and teeth are like that of modern whales, but more intriguingly, Ambulocetus did not have ears to pick up vibrations, but instead detected them through its jaw. This form of hearing is typical of marine animals, the direction from which vibrations come from can be pinpointed with great accuracy, a quality that only adds to the success of an ocean-bound predator. 

Fossils of Ambulocetus have most commonly been found in Pakistan, it is estimated to have been able to reach up to 3 metres long. Due to Ambulocetus’s ancestry to the whales, it is described as a transitional fossil. Ambulocetus lived in a period of great significance in the whales evolutionary history, living in the middle Eocene, whale evolution accelerated and by the end of the Eocene, whales had fully immersed themselves into underwater life, they had left the land for good.
As far as evidence goes, Ambulocetus was an important but very short lived animal in life’s evolutionary history. By 49 million years ago, traces of Ambulocetus disappeared and there are few clues as to why.