2024-04-03 11:00:12
A group of paleontologists from the University of Zurich recently revealed a surprising discovery: a giant freshwater dolphin in the Amazon region of Peru.
This dolphin, named Pebanista yacuruna, lived 16 million years ago and measured between 3 and 3.5 meters, classifying it as the largest river dolphin known to date. The name of thespecies is inspired by a legendary aquatic people of theAmazon. Surprisingly, its closest living relatives are found among the river dolphins of South Asia.
Credit: Jaime Bran
Existing river dolphins are among the most threatened cetaceans, with several species critically endangered.extinction. Pebanista belongs to an ancient group, the Platanistidae, which flourished between 24 and 16 million years ago. The discovery suggests that these marine ancestors adapted to the prey-rich freshwater ecosystems of ancient Amazonia. The Amazon region, 16 million years ago, was dominated by a vast system of lakes and swamps, very different from the current landscape. With the evolution of the Pebas system in modern Amazonia, the ecological niche of Pebanista disappeared, leading to its extinction. This allowed other species, like the ancestors of today’s Amazonian river dolphins, to exploit new habitats.
The study, published in Science Advances, sheds new light on the evolution of freshwater dolphins, revealing that Pebanista shared unique characteristics with South Asian river dolphins, including facial bone structures linked to echolocation. This capacity is vital for navigation and hunting in turbid waters, where the visibility is weak.
Schematic representation of the region highlighting the presence of epicontinental waters in South America (pale blue). Existing geographic ranges of dauphin of the Amazon River Inia and the river dolphins of South Asia Platani (HAS). Distribution of fossil records of Iniidae/Platanistidae in the Pebas system of Miocene Lower Middle Miocene (B) and the Upper Miocene Acre system (C). Modified from Benites-Palomino et al.
Searching for fossils in the Amazon is extremely difficult, with conditions only being favorable in the dry season. The type specimen of Pebanista was discovered in 2018 during an expedition of more than 300 kilometers along the Napo River, led by the team of Rodolfo Salas-Gismondi. This discovery represents a significant contribution to our understanding of the past diversity of freshwater ecosystems and the evolution of cetaceans.
This research highlights the importance of the Amazon not only as a current reservoir of biodiversity but also as a key witness to past ecosystems, providing unique perspectives on the evolution of life on Earth.
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