Pebanista yacuruna is the closest relative of living South Asian river dolphins (genus Platanista).
Pebanista yacuruna lived in the Miocene proto-Amazonia of Peru approximately 16 million years ago.
The ancient dolphin had an estimated body length of 2.8 to 3.5 m (9.2-11.5 feet), making it the largest freshwater species of odontocete (dolphins, porpoises, and all other whales possessing teeth) known.
Such a large size, also recorded in other proto-Amazonia inhabitants (i.e. fishes and crocodilians), might be attributed to the large resource availability in proto-Amazonian ecosystems.
“Sixteen million years ago, the Peruvian Amazonia looked very different from what it is today,” said Dr. Aldo Benites-Palomino, a paleontologist at the University of Zurich.
“Much of the Amazonian plain was covered by a large system of lakes and swamps called Pebas.”
“This landscape included aquatic, semi-aquatic and terrestrial ecosystems (swamps, floodplains, etc.) and stretched across what is today Colombia, Ecuador, Bolivia, Peru and Brazil.”
“When the Pebas system began to give way to modern Amazonia about 10 million years ago, new habitats caused Pebanista yacuruna’s prey to disappear, driving the giant dolphin to extinction.”
“This opened an ecological niche that was exploited by relatives of today’s Amazon river dolphins (genus Inia), which were also facing extinction in the oceans due to the rise of new cetaceans, such as modern oceanic dolphins.”
Pebanista yacuruna was a member of Platanistoidea, a group of dolphins that were common in the world’s oceans between 24 and 16 million years ago.
“We discovered that its size is not the only remarkable aspect,” said Dr. Aldo Benites-Palomino, a paleontologist at the University of Zurich and the Museo de Historia Natural-Universidad Nacional Mayor de San Marcos.
“With this fossil record unearthed in the Amazon, we expected to find close relatives of the living Amazon River dolphin, but instead…
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