A four-legged prehistoric whale fossil found in Peru

Washington:

Paleontologists have discovered a well preserved fossil from an amphibious ancestor on all fours of whales, a discovery that sheds new light on the passage of mammals from the land to the ocean.

The ancestors of whales and dolphins walked on Earth about 50 million years ago in areas that now include India and Pakistan.

Paleontologists have already discovered partial fossils of the species in North America dating back 41.2 million years, suggesting that cetaceans no longer had the ability to support their own weight and to walk on the Earth.

The new specimen, described in a study published Thursday in the journal Current Biology, is 42.6 million years old and provides new information on the evolution of cetaceans.

The fossil was discovered about 1 km from the Pacific coast of Peru, at Playa Media Luna.

The mandibles grazed the soil of the desert and, during excavations, the researchers discovered the lower jaw, teeth, vertebrae, ribs, parts of front and back paws and even the long, probably webbed, fingers of the jaw. ancestor of the whale.

On the basis of his anatomy, scientists say that this cetacean about four meters long could walk and swim.

"A part of the vertebra of the tail had similarities with that of the current semi-aquatic mammals such as the otter," AFP Olivier Lambert, principal author of the Royal Institute of Natural Sciences, told AFP. Belgium.

"This would have been an animal that would have started to use more and more its tail to swim, which differentiates it from older cetaceans from India and Pakistan."

Pieces of four-legged whales were found in Egypt, Nigeria, Togo, Senegal and Western Sahara, but they were so fragmented that it was impossible to decide decisively if they were able to to swim.

"This is the most complete specimen ever found for a four-legged whale outside of India and Pakistan," said Lambert.

If the whale in Peru could swim like an otter, the researchers speculated that it probably would have crossed the Atlantic from the west coast of Africa to South America. Due to continental drift, the distance was half that of today, about 800 miles, and the east-west current of the time would have facilitated their journey.

This discovery would make less likely another assumption that whales would have reached North America via Greenland.

The Pisco basin, off the southern coast of Peru, probably contains many fossils because of its excellent conservation conditions.

"We have work for at least the next 50 years," said paleontologist Lambert.

(This story has not been changed by NDTV staff and is generated automatically from a syndicated feed.)

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