What's 13 feet long and has webbed feet with small hooves? It's a whale, according to researchers examining a 42.6-million-year-old fossil found near Peru's Pacific coast. The four-legged early whale, which could apparently move on land as well as in the sea, is the most complete fossil of its kind outside what is now India and Pakistan, where whales first began to evolve from dog-sized carnivorous mammals 50 million years ago, researchers say in a press release. It's also the first found near the Pacific. Researchers believe the whale's tail allowed it to swim like a giant otter or beaver. It apparently could stay in the water for weeks at a time, but likely returned to land to rest and give birth.
The whale has been named Peregocetus pacificus, meaning "the traveling whale that reached the Pacific," the BBC reports. In a study published in Current Biology, the researchers say the fossil suggests whales started spreading around the world's oceans by crossing the south Atlantic, which was much narrower 42 million years ago. "Whales are this iconic example of evolution," says Travis Park, a whale researcher at the Natural History Museum. "They went from small hoofed mammals to the blue whale we have today. It's so interesting to see how they conquered the oceans." Lead researcher Olivier Lambert of the Royal Belgian Institute of Natural Sciences tells AFP that the Pisco Basin region where the whale was found has enough fossils to keep his team busy for 50 years. (More whales stories.)