http://www.newsweek.com/peregocetus-bizarre-ancient-whale-discovered-1385832

Artist impression of Peregocetus pacificus. A. Gennari Share Tech & ScienceAn ancient whale that had four legs, hooves and an otter-like tail has been discovered in marine sediments on the coast of Peru. The 13 foot creature lived around 42.6 million years ago and appears to have been able to walk on land and swim in the sea.

The find raises questions about the evolution of cetaceans—the group that includes whales and dolphins. According to the U.K.'s Natural History Museum, the land-based ancestors of cetaceans lived around 50 million years ago. But at some point the goat-sized creature Pakicetus—found in what is now Pakistan and India—ended up back in the sea. From this the group evolved, eventually resulting in the species we see today.