![\"Artistic](\"https:\/\/images.newscientist.com\/wp-content\/uploads\/2024\/03\/20144438\/SEI_196651810.jpg?width=1200\")
<\/div>An artistic reconstruction of Pebanista yacuruna in the murky waters of the Peruvian proto-Amazon<\/p>\n
Jaime Bran<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n
The Amazon<\/a> basin was once home to freshwater dolphins that grew up to 3.5 metres long \u2013 making them the largest river dolphins known to science.<\/p>\n Researchers made the surprise discovery during a 2018 expedition in Peru, says Aldo Benites-Palomino<\/a> at the University of Zurich in Switzerland. The team saw the animal\u2019s fossilised skull poking out of a river embankment and knew right away it was a dolphin. Close analysis confirmed the giant skull was unlike any ever found.<\/p>\n The researchers have now named the new species Pebanista yacuruna<\/em>. The name honours a mythical aquatic people \u2013 the Yacuruna \u2013 believed to inhabit underwater cities in the Amazon basin.<\/p>\n The 16-million-year-old fossil was unearthed in a region that was once covered by a lake that was \u201cinsanely big \u2013 almost like a little ocean in the middle of the jungle\u201d, says Benites-Palomino. Based on the small size of the ancient dolphin\u2019s eye sockets and its large teeth, he says P. yacuruna<\/em> was probably a predator with poor eyesight. It relied heavily on echolocation<\/a> to find fish. \u201cWe know that it was living in really muddy waters because its eyes started to reduce in size,\u201d says Benites-Palomino.<\/p>\n <\/p>\n Because the fossil was found in the Amazon basin, the researchers expected its closest living relatives to be modern Amazon river dolphins<\/a>. Instead, they found P. yacuruna<\/em> was more closely related to river dolphins of South Asia. Like them, this ancient species has raised crests on its skull that improved its ability to echolocate.<\/p>\n P. yacuruna<\/em> may have been driven extinct during a broader ecological shift, says Benites-Palomino. \u201cAround 11 to 12 million years ago, this mega wetland system started to drain, giving way to the modern Amazon. A lot of species disappeared at that moment, and that might also have been the fate of this giant dolphin.\u201d<\/p>\n Topics:<\/p>\n<\/section><\/div>\n