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Unknown species of ancient four-legged whales discovered in Peru



Interpretation of the artist Peregocetus pacificus four-legged whale from the middle Eocene period.
Illustration: Alberto Gennari

The discovery of a 42-million-year-old four-legged whale sheds light on the evolution and geographical distribution of these aquatic mammals.

Ancestors of modern whales and dolphins arose from a small, tetragonal limb that lived in South Asia about 50 million years ago during the Eocene. Research on fossil fuels shows that pioneers of these aquatic mammals reached North America 41.2 million years ago, swimming from West Africa through the Atlantic. The unexpected discovery of an earlier unknown quadrangular whale for 42.6 million years along the Peruvian coast has led to an important addition to this story: ancient whales made South America, not North America, their first home in the New World. . Details of this discovery were published today in Current Biology

A new species is called Peregocetus pacificus . Its remarkably well-preserved remains were found on Playa Media Luna in 2011, where paleontologists have recovered most of their skeletons, including the jaw, front and back legs, spine and tail bits. The dating of the marine sediment, within which fossils Peregocetus were found to the middle Eocene.

Interpretation of the artist Peregocetus pacificus, going on land.
Illustration: Alberto Gennari

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

Analysis of fossils Peregocetus shows that it was well adapted to both land-based and sea-bearing characteristics similar to modern otters and beavers. This animal was relatively large, about 4 meters (13 feet) long, more than twice the size of today's otters. The groundbreaking capabilities of the Perogecet were demonstrated by small hooves at the ends of the fingers and the orientation of its hip hips, indicating a quadrilateral motion on the ground. At the same time, he had tail bones similar to beards and otters, which means that his tail played an important role in his water abilities. Finally, according to researchers, the size of the fingers and toes indicate the presence of overlapping appendages.

Scam & # 39; ianil bones restored at Playa Media Luna.

The discovery adds new insights on the geographical distribution of ancient whales at this stage in their evolutionary history. Quinchini whales have probably reached South America, crossing the south-Atlantic ocean from the west coast of Africa, researchers say. The animal was assisted by surface currents to the west, and the distance between Africa and South America was about half what it is today, which makes the campaign comfortable. Having arrived in South America, Peregocetus settled in the Pacific Ocean along the Peruvian coast, eventually moving to North America.

Playa Media Luna, so older amphibians [a group that includes whales and dolphins] can be detected in the future, "Lambert said.

"This is a truly amazing discovery based on a relatively complete skeleton that shows that truly ancient whales are able to swim and the journey reached America much earlier than previously thought," Erich Fitzgerald, Senior Curator of Vertebrate Paleontology at Victoria Museums, Melbourne, explained in a letter from Gizmodo. It has really interesting implications for our understanding of the evolution of whales. Perhaps the whole chapter in the history of whale evolution, which took place in South America and elsewhere in the Pacific and South Pacific, which we did not know, "said Fitzgerald, who is not associated with a new study.

Reconstruction showing the preserved parts of the skeleton Peregocetus pacificus in both terrestrial and aquatic configurations.
Image: Olivier Lambert et al., 2019 / Current biology

Paleontologist Felix Marx of the University of Liege in Belgium stated that the new study is "significant" but "fairly simple", since "not so much" is being criticized here. "- he wrote in a letter to Gizmodo. Marx is good friends with Lambert, a leading author, and they share the same office, so he can not "guarantee impartiality." This refusal of the statement, he said that the new fossil is "very convincing", and this gives the scientist a better idea. about how these early whales spread throughout the globe.

"We have long known that quadruped whales reached North America, but this is the first reliable record from South America and thus the first one from South America. the hemisphere, "said Marx. – I would like to know how far south they really did it. Who knows, maybe once on the coasts of Chile were once and the ancient whales? "

To what he added:" This study also once again shows the great potential of Peru as the bench of the Yunnile Treasury. This is a world-class website, and I expect that we will receive more surprises until we continue to study it. "

Fitzgerald repeated this feeling.

"There are clearly more turns in the whale story that we have not even begun to imagine," he said. "Undoubtedly, there are still many cetacean surprises in the southern hemisphere."

[Current Biology]


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