Peru: Fossil remains of a four-legged whale

A team of researchers has discovered the remains of a four-legged whale similar in shape to a 42.6-million-year-old otter on the Peruvian coast, according to a study published Thursday in the journal Current Biology.

According to the researchers, the presence of small helmets on the fingertips and toes of the whale and their morphology of the hip and limb suggest that this whale could walk on land.

In addition, they ensure that the anatomical features of the tail and feet, including the long, probably webbed appendages, similar to an otter, indicate that he was also a good swimmer.

"This is the first undisputed record of a quadruped whale skeleton for the entire Pacific Ocean, probably the oldest in America and the most complete outside of India and Pakistan, "said Olivier Lambert, of the Royal Belgian Institute of Natural Sciences.

The anatomical details of the skeleton allowed them to infer that the animal was able to maneuver its large body (up to 4 meters long, tail included), both on land and in l & # 39; water. For example, the characteristics of the caudal vertebrae (in the tail) resemble those of beavers and otters, suggesting a significant contribution of the tail during swimming.

The international team continues to study the remains of other whales and dolphins in Peru. "We will continue to search in places with layers as old as Playa Media Luna, or even older, so that the oldest amphibian cetaceans can be discovered in the future," concludes Lambert.

History and ancestors

Until this discovery, it was known that cetaceans, the group comprising whales and dolphins, originated more than 50 million years ago in Southeast Asia from a small ancestor to four legs and hooves.

Now, they have a new perspective on the evolution of whales and their dispersion in the world.

The geological age of the new four-branched whale and its presence along the west coast of South America strongly support the hypothesis that the first cetaceans arrived in the New World from the South Atlantic, from the West coast of Africa to South America, the researchers report.

On the excavation area

A few years ago, Mario Urbina, co-author of the Natural History Museum-UNMSM study in Peru, discovered a promising area to search for fossils in the southern coastal desert of this country, named Media Luna Beach.

In 2011, an international team, composed of members from Peru, France, Italy, the Netherlands and Belgium, organized a field expedition during which they uncovered the remains of 39, an old whale, named "Peregocetus pacificus". It means "whale traveling in the Pacific".

In this line, Lambert explained that "by digging around the bones of the outcrop, we quickly realized that it was the skeleton of a quadruped whale, with his forelegs and hind limbs ". Using microfossils, the sediment layers where the skeleton was placed date back to the middle Eocene, 42.6 million years ago.