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WASHINGTON (Reuters) – Scientists have uncovered fossils of a four-legged whale in the coastal desert of southern Peru, which flourished at sea and on land about 43 million years ago thanks to a discovery that illuminates a crucial step in the early evolution of cetaceans.
The mammal, 13 meters long (4 meters), named Peregocetus pacificus, represents a crucial intermediate step before whales become fully adapted to a marine life, scientists said Thursday.
His four limbs were able to support his weight on land, which meant that Peregocetus could return to the rocky coast to rest and perhaps give birth while spending much of his time at sea. His feet and his hands had small hooves and were probably webbed to help with swimming. With long fingers and toes and relatively thin limbs, moving on the ground may not have been easy.
Its elongated snout and sturdy teeth – large incisors and canines to grasp, as well as grazing flesh molars – allowed Peregocetus to capture medium-sized prey like a fish.
"We think that he was feeding in the water and that his underwater locomotion was easier than on land," said paleontologist at the Royal Belgian Institute of Natural Sciences, Olivier Lambert , who led the research published in the journal Current Biology.
"Some vertebrae in the tail region share strong similarities with semi-aquatic mammals such as otters, indicating that the tail was primarily used for underwater locomotion," Lambert added.
The origins of whale evolution were poorly understood until the 1990s, when fossils of the first whales were discovered. Various fossils have shown that whales evolved just over 50 million years ago in Pakistan and India from terrestrial mammals living in hooves, distantly related to hippopotamuses and the size of whales. 39, a medium sized dog. It took them millions of years to spread around the world.
Peregocetus represents the most complete quadruped whale skeleton outside India and Pakistan, and the first known from the Pacific region and the southern hemisphere.
According to Lambert, its presence in Peru suggests that quadruped whales have spread from South Asia to North Africa, and then crossed the South Atlantic to reach the New World. Peregocetus shows that the first whales to reach the Americas still retained the ability to move on land.
Over time, the forelimbs of the cetaceans turned into fins. The hind limbs eventually become mere vestiges. It was only 40 million years ago, the whale line was transformed into fully marine animals, then into two groups of live cetaceans: baleen whales and toothed whales. like dolphins and orcas.
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