The Peregocetus pacificus whale is estimated to have lived about 43 million years ago. The most surprising fact is that this whale had four limbs and the ability to walk on bare earth and swim in the ocean. Its small limbs could have been the reason why the whale is believed to have evolved over the years into the modern whale we know today: Most likely its life was easier in the sea than on land.

More information:

theguardian.com/whale-legs-fossil