Fossil of whale on all fours: a recently discovered whale walking on land and swimming in the sea

This illustration shows what Peregocetus could have looked like.

A. Gennari

A fossilized four-legged whale, webbed feet and hoofed toes reveals new details on the evolution and geographical distribution of whales around the world.

Paleontologist Mario Urbina and his team discovered the fossil in 2011 along the Peruvian coast, according to a study published Thursday in the journal Current Biology. They were able to recover most of his skeleton, including the jaw, paws, part of his back and tail. The fossil dates from 42.6 million years ago and dates back to the middle Eocene times.

It is the oldest known whale found in this part of the world and the most complete skeleton discovered outside of India and Pakistan. Scientists believe that the creature – which looks like an otter – may well be a first form of whale that has not yet fully migrated to life in the water. This unusual find contains clues about the spread of whales on the planet and indicates that ancient whales have settled in South America before North America.

The skeletons of the four-legged whale indicate that she would have been at home on land and in the water.

Lambert et al./Current Biology

The discovery team christened the creature "Peregocetus pacificus" in Latin for "the wandering whale that has reached the Pacific".

"This is the first indisputable record of a quadruped whale skeleton for the entire Pacific Ocean, probably the oldest in the Americas and the most complete outside of the world. India and Pakistan, "said Dr. Olivier Lambert, co-author of the study.

According to the amazingly well preserved fossil, the animal would have been about 11 feet long. He had a large tail and four legs with hoofed toes that were probably webbed, making the creature well adapted to the land and the sea.

It was already known that whales and dolphins had adapted over the years to four-legged terrestrial animals as they transitioned into life in the water. However, the way they traveled from South Asia to South America remains a mystery.

The researchers suggest that the creatures have probably crossed the South Atlantic Ocean from the west coast of Africa, aided by surface currents. Because Africa and South America were much closer millions of years ago, whales would not have had so much trouble making the trip. Once settled in Pacific waters near Peru, they would eventually go to North America.