The changing climate of Earth has prompted several marine dolphin species to evolve and adapt to freshwater ecosystems to escape extinction.
In the Napo River, Loreto, Peru, scientists have uncovered the fossil of the largest river dolphin species ever known: Pebanista yacuruna. This colossal dolphin measured between 2.8 and 3.5 meters, surpassing the current maximum size of 2.5 meters for river dolphins. The discovery is remarkable as it reveals a cetacean that lived approximately 16.5 million years ago and became extinct around 11 million years ago.
The paleontological finding was published on March 20 in the journal Science Advances, following six years of study and analysis of a fossilized skull.
Aldo Benites-Palomino, the lead author and researcher at the University of Zurich, noted that the fossil was discovered during a field expedition in 2018. The team found the skull in a rock wall, connecting it to other fragments found nearby.
Although Pebanista yacuruna was found in South America, it belongs to the family Platanistidae, which includes the two existing Asian river dolphins: the Ganges dolphin (Platanista gangetica) and the Indus dolphin (Platanista minor).
This discovery highlights the evolutionary links between Asian and South American river dolphins, suggesting that members of this lineage migrated to freshwater environments in South America before the ancestors of the modern Amazon river dolphin, Inia.
The name Pebanista yacuruna references the ancient Pebas Lake, rich in biodiversity, and yacuruna, a mythical Amazonian creature from Quechua mythology.
Benites-Palomino emphasized the significance of this find, as river dolphin fossils are rare globally, and much remains unknown about their history.
The study illustrates that the large body size of this dolphin might be attributed to the rich resources available in ancient Amazonian ecosystems, where competition and predation were minimal.
Despite the fossil only providing a glimpse into the dolphin's anatomy, researchers used existing data on modern cetaceans to estimate its size and characteristics, revealing a creature that was likely nearly blind and relied on echolocation to navigate its murky habitat.
Ultimately, the fossil raises intriguing questions about how this dolphin species reached South America and adapted to freshwater environments during past climate changes.
As climate change accelerates, the study serves as a reminder of the fragility of ecosystems and the potential for extinction events.