The Amazon River was once home to a massive freshwater dolphin.

Pebanista Yacluna are the closest living relatives River dolphin of South Asia (genus Platanista).

Pebanista Yacluna About 16 million years ago, it lived in the Miocene Amazon of Peru.

The ancient dolphin was estimated to be 2.8–3.5 m (9.2–11.5 ft) long, making it the largest freshwater dolphin species. dentate (Dolphins, porpoises, and all other toothed whales) are known.

Such large sizes have also been recorded in other proto-Amazonian inhabitants (i.e. fish and crocodiles) and may be due to the greater availability of resources in the proto-Amazonian ecosystem.

“16 million years ago, the Peruvian Amazon looked very different from what it looks like today,” said Dr. Aldo Benitez Palomino, a paleontologist at the University of Zurich.

“Most of the Amazon plain was covered by large lake and swamp systems called pebas.”

“This landscape included aquatic, semi-aquatic, and terrestrial ecosystems (swamps, floodplains, etc.) and spanned what is now Colombia, Ecuador, Bolivia, Peru, and Brazil.”

“When the Pebas system began to give way to what is now the Amazon about 10 million years ago, the new habitat caused Pebanista Yaclunaprey disappears, and the giant dolphin is driven to extinction. ”

“This opened up an ecological niche that is used by relatives of today's Amazon river dolphins (genus Delphinus). inia), and with the rise of new cetaceans such as modern dolphins, they were on the brink of extinction in the oceans. ”

holotype skull Pebanista Yacluna. Image credit: Benites-Palomino other., doi: 10.1126/sciadv.adk6320.

Pebanista Yacluna was a member of platanist ideasa group of dolphins that were common in oceans around the world from 24 million to 16 million years ago.

“We discovered that size is not the only thing to note,” said Dr. Aldo Benitez Palomino, a paleontologist at the University of Zurich and the Natural History Museum of the National University of San Marcos. Told.

“With this fossil record excavated in the Amazon, we expected to find a living relative of the Amazon river dolphin, but instead we found the Amazon river dolphin's closest relative. Pebanista Yacluna It is a river dolphin from South Asia. ”

“Pebanista Yacluna and Platanista Both share a highly developed facial crown, a specialized bone structure associated with echolocation, the ability to emit high-frequency sounds and “see” by listening to their echoes, which is useful for hunting. relies heavily on this. ”

“Echolocation and biosonar are even more important for river dolphins because the waters they live in are very murky, which impedes their vision,” said Dr. Gabriel Aguirre Fernandez, a paleontologist at the University of Zurich.

“The elongated snout with many teeth suggests that: Pebanista Yacluna Like other species of river dolphins today, they eat fish. ”

large adult skull Pebanista Yacluna It was discovered in 2018 at an exposed stratigraphic level along the Rio Napo in Loreto, Peru.

“After 20 years of research in South America, we have discovered several giant dolphins in this region, but this is the first of its kind,” said Dr. Marcelo Sánchez Vilagra, a paleontologist at the University of Zurich. .

“We were particularly intrigued by its unique and deep biogeographical history.”

team's paper Published in the Journal on March 20, 2024 scientific progress.

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Aldo Benitez Palomino other. 2024. The largest freshwater toothed whale: A relative of the South Asian river dolphin that lives in the primitive Amazon. scientific progress 10(12); doi: 10.1126/sciadv.adk6320