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Discovered the first archaeocete that, over 42 million years ago, reached the Pacific Ocean

The exceptional discovery was made in the Peru desert by an international team including researchers of the Earth Sciences Department of the University of Pisa.

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Its name is Peregocetus pacificus, which means "the cetacean traveler who reached the Pacific", and the discovery of its fossil skeleton in sediments over 42 million years old is fundamental to trace back the route followed by the whale and dolphin ancestors in the long travel that, between 50 and 40 million years ago, took them from their center of origin between India and Pakistan to colonize all the oceans.

Peregocetus ricostruzione
Artistic reconstruction of Peregocetus.

The important discovery, just published by the prestigious journal "Current Biology", was made by an international team of paleontologists and geologists from the universities of Pisa and Camerino and the natural history museums of Paris, Brussels, and Lima whose research in the coastal desert of Peru have already provided important results, such as the finding in the same place of Peregocetus, but in more recent rocks, of Mystacodon selenesis, the oldest known baleen whale ancestor.

"A particularly interesting aspect of this new archaeocete - says Giovanni Bianucci, paleontologist of the Earth Sciences Department of the University of Pisa (Italy) who took part in the excavation and study of the fossil - is that the presence of small hooves at the tip of fingers and toes, together with the shape of the pelvis and limbs, suggests that Peregocetus was still able to walk on land, while the long and flat fingers, probably palmate, and the anatomical features of the tail indicate that it was also a good swimmer. It would therefore be an intermediate stage between today's whales and dolphins (no longer able to move out of the water) and their four-legged terrestrial ancestors, that is, an animal with a life-style similar to the otter."

foto bianucci
Prof. Giovanni Bianucci.

It is through the detailed study of its fossil skeleton that researchers were able to establish that this archaeocete was able to maneuver its four-meter long body both on land and in the water. For example, the fact that the caudal vertebrae are similar to those of beavers and otters suggests that the tail provided a significant contribution to swimming.

"It is extraordinary to have found a cetacean in rocks so ancient and so far from the area of origin of these marine mammals - explains Claudio Di Celma, geologist of the School of Sciences and Technologies of the University of Camerino (Italy) who took care of the stratigraphic study of the area where Peregocetus was found. In fact, this discovery represents the first indisputable record of a quadruped cetacean in the Pacific Ocean, probably the oldest ever found in America and the most complete outside India and Pakistan”.

scavo Peregocetus6
Field excavation of Peregocetus in the Peruvian desert.

According to the researchers, the geological age of this archaeocete and its presence along the western coast of South America strongly support the hypothesis that the first cetaceans reached the New World crossing the South Atlantic from the west coast of Africa to South America. These ancestors of whales and dolphins would have been assisted in their travel by the surface currents that at that time flowed from the West to the East and by the shorter distance (half of the present one) between the two continents.

Meanwhile, research in Peru goes on and the international team continues to make new discoveries. "Every expedition - concludes Giovanni Bianucci - gives us new surprises. Everything is possible thanks to an exceptional fossil deposit and to an extraordinary research group".

Media Luna Perù2
The Peru desert.

peregocetus dispersione 
The protocetid way from India and Pakistan to the Pacific Ocean as traced back thanks to

  • 5 April 2019

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