Paleontologists discover giant fossilized river dolphin skull in Peru

Not all dolphins live in the salty ocean. Although rare, some river dolphins live and eat in freshwater and are best known for their candy-colored hues. Now, paleontologists have discovered a fossilized skull belonging to a 16-million-year-old extinct river dolphin species in Peru called The pebanist snorted. It can grow to about 10 to 11 meters long and is the largest known river dolphin species known to science. from Peban described in a study published March 20 in the journal Advances in science.

Name The pebanist snorted is inspired by the Yacuruna, a mythical water people who legends say inhabit underwater cities in the Amazon basin and are similar to the god Neptune in Greek mythology. The fossilized skull was found in the Peruvian Amazon and belongs to the group Platanistoidea. This group was a common animal in Earth’s oceans between 24 and 16 million years ago. The team believes that their mostly saltwater-dwelling ancestors invaded the freshwater-rich ecosystems of the early Amazon and learned to adapt to this new environment.

“Sixteen million years ago, the Peruvian Amazon looked very different than it does today,” Aldo Benites-Palomino, a study co-author and paleontologist at the University of Zurich in Switzerland, said in a statement. Most of the Amazon plain was covered by a large system of lakes and swamps called Pebas.

[Related: Eavesdropping on pink river dolphins could help save them.]

This landscape stretched across present-day Colombia, Ecuador, Bolivia, Peru and Brazil and included a variety of ecosystems in its lakes and swamps. About 10 million years ago, the Pebas system began to give way to the flood plain that Amazonia looks like today. of Pebanista prey began to disappear as the landscape began to change, driving these giant dolphins to extinction. with from Peban out of the picture, called relatives of today’s Amazon river dolphins INDIA there was an opportunity to sneak in.

While these pink dolphins may look similar to the extinct ones from Peban, are not directly related. of Pebanista The closest living relatives of this newly discovered species are found in South Asia.

“We found that its size is not the only remarkable aspect,” says Benites-Palomino. “With this fossil record discovered in the Amazon, we expected to find relatives of the living Amazon river dolphin – but instead, the closest cousins ​​of from Peban are river dolphins of South Asia (gen Platani)”

both from Peban AND Platani they have highly developed facial ridges that help them with echolocation. This is when they emit high-frequency sounds and listen to their echoes in order to “see” their prey through the sounds.

“For river dolphins, echolocation, or biosonar, is even more critical since the waters they inhabit are extremely turbid, which hinders their vision,” study co-author and University of Zurich paleontologist Gabriel Aguirre-Fernández said in a statement.

[Related: This dolphin ancestor looked like a cross between Flipper and Moby Dick.]

of Pebanista the elongated snout with many teeth suggests that it fed on fish as other river dolphins did. Modern Amazon river dolphins are called vote are considered critically endangered and their main threats include habitat loss and degradation and entanglement in fishing gear.

The Amazon rainforest remains a very difficult place for paleontological fieldwork. Fossils like these are only accessible during the dry season, when water levels drop enough to expose ancient rock layers. If the fossils are not collected in time, they may be washed away during the rainy season.

The specimen was found in 2018 in an expedition led by Peruvian paleontologist Rodolfo Salas-Gismondi, who completed his postdoctoral work at the University of Zurich. The team traveled more than 180 miles from the Napo River in northeastern Peru and collected dozens more fossils. The dolphin’s skull is now in the Museo de Historia Natural in Lima.

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