THE SKULL OF EXTINCT 16-MILLION-YEAR-OLD GIANT DOLPHIN SPECIES DISCOVERED IN PERU

One of the most biodiverse ecosystems to have ever existed on Earth, the Peruvian Amazon rainforest was submerged beneath a vast lake called Pebas approximately 16 million years ago. Among the species that called it home was the largest freshwater dolphin known to science. Paleontologist Aldo Benites-Palomino discovered a fossilised jaw bone while on a field trip around Peru's Napo River in 2018, shattering the mystery surrounding this creature.

The moment I realized what it was, I could see the tooth sockets. I exclaimed, "Look, a dolphin!" We were in shock, Benites-Palomino said to The Guardian. Initially, he assumed the dolphin had to be a progenitor of the modern South American pink dolphins found in the Amazon River. Further investigation, however, revealed that not only was it a totally distinct species that is now extinct, but that its nearest relatives are located halfway around the globe. More precisely, about 6,200 miles away, in the Ganges and Indus rivers in South Asia.

According to Benites-Palomino on TikTok, "It's hard to find fossils from this era since they're only accessible during the dry season when the Amazon rivers are low enough to expose rocks from the past."

Pebanista yacuruna is the name given to the recently found species in remembrance of the Yacuruna, a mythological aquatic people thought to reside in underwater cities throughout the Amazon basin. This creature had small eyes, a bony structure called a facial crest that allowed it to navigate by echolocation, and it could grow up to 11.5 feet long. The waters that river dolphins live in are very muddy, which impairs their vision. For this reason, echolocation, or biosonar, is even more important for them, according to Gabriel Aguirre-Fernández, a researcher from the University of Zurich who also took part in this study.

The Pebanista Yacuruna are thought to have started out as ocean dwellers before relocating to freshwater environments in quest of new food sources. And just as these dolphins underwent evolutionary changes that enabled them to flourish in their new surroundings, these animals might also have the answer for today's threatened freshwater dolphin populations, whose ecosystems are being negatively impacted by pollution and global warming.

According to Benites-Palomino, who spoke with New Scientist, "This mega-wetland system started to drain around 11 to 12 million years ago, giving way to the modern Amazon." "Many species vanished at that very moment, and this enormous dolphin might have been among them."

This enlightening fossil is currently housed in Lima, Peru's Museum of Natural History, the same organisation where Benites-Palomino began his professional career as a Research Associate. However, his research will go much further. Benites-Palomino sums up, "The discovery of Pebanista in the Peruvian Amazon only reasserts one thing." "Many animal groups are having their stories rewritten by our fossils."