Existence of Giant Dolphins Inhabiting the Amazon River Revealed

LIMA – Freshwater dolphins in the Amazon and South Asia it is renowned for its unique pink skin and its status as an endangered mammal.

As reported by IFL Science, the discovery of a new fossil of a 16.5 million year old freshwater river dolphin helps answer questions about the origins of this extraordinary creature.

The skull and other fossils of an ancient river dolphin were discovered in Rio Napo, Loreto, Peru in 2018 and are more than 16.5 million years old, dating from the Early to Middle Miocene.

Named Pebanista yacuruna by the research team, this dolphin is estimated to have been around 3 meters (9.8 feet) long, making it the largest known freshwater dolphin.

P. yacuruna (top left) is the largest compared to the other four main species.
Gray lines indicate maximum sizes, and white lines indicate minimum recorded or reconstructed sizes of each species.

P. yacuruna is also thought to have a thick body with a long snout and very small eyes, almost completely blind. Researchers suspect that these ancient dolphins navigated the muddy waters of the Amazon by using small melons on their foreheads for echolocation.

Looking closely at its skull, which had a long snout, large teeth and a well-developed forehead, the team concluded that this ancient dolphin had fully adapted to freshwater life.

The currently known Amazon river dolphins evolved from a lineage called Iniidae. However, the evolution of South Asian river dolphins, known as Platanistidae, is still unknown because fossils of these ancient mammals are very rare.

This group includes living species such as the Ganges river dolphin (Platanista gangetica gangetica), which survives in the waterways of the Ganges river in India.

After conducting a phylogenetic analysis, the research team concluded that the fossilized remains of the skull were the closest relatives of the Ganges river dolphin.

This, coupled with the dolphin’s characteristics that allow it to be fully adapted to freshwater, leads the team to believe that this group of Platanistida began living in freshwater systems in South Africa and South America before the ancestors of the Iniidae clade that gave rise to the modern Amazon river dolphin.

This discovery is important for understanding the diversity and evolution of freshwater dolphins, as well as aiding conservation efforts to protect this endangered species.
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(wbs)