A new discovery in Panama has filled the gap in evolutionary biology, as scientists find 6 million year old fossils of dolphin ancestor that could provide answers how the intelligent mammal migrated from the ocean to rivers.
Initially thought that the fossils dug within the rocky shoreline belonged to a shark-toothed dolphin, researchers discovered that it was, in fact, a part of a previously unseen species, and an ancient ancestor to one particular freshwater mammal.
The fossils discovered include a half skull, lower jaw completed with teeth, the right shoulder blade and two small flipper bones that allowed researchers to gather knowledge about its appearance, and ability to navigate the murky rivers or coastal waters.
The long-extinct and previously undiscovered species of dolphin has been dubbed Isthminia panamensis, and was reportedly 9 feet long, with paddle-like flippers, a flexible neck, and a head with long, narrow snout.
It’s name was likely given due to the location where it was found, Panama, and due to the belief that it used to live in the channel connecting the “Atlantic and the Pacific Ocean before the isthmus of Panama formed.”, as stated by Nick Pyenson, a paleobiologist of the Smithsonian Institution in Washington. It is said to be between 5.8 million to 6.1 million years old.
According to the study’s co-author, Aaron O’Dea of the Smithsonian Tropical Research Institute in Panama, the Isthminia panamensis is actually the closest known relative to today’s Amazonian river dolphins, Inia geoffrensis. The newly discovered species can prove itself to be the missing link between the river dolphins and their oceanic ancestors.
Many species of freshwater animals, such as turtles, stingrays and manatees, who live in the Amazon are believed to have marine ancestors, but Isthminia now offers clear proof that the same might’ve happened for river dolphins, and provides better understanding of when they shifted from saltwater to freshwater.
Smithsonian experts believe that Isthminia panamensis, was pushed inland and away from the crowding ocean waters with the migration of other species, along with the unfortunate consequence in climate change and rising of water levels.
That might ring familiar to many modern day situations, as the mammals are more likely to seek the colder depths with the gradual increase of temperatures across our planet.
Currently, there are four species of river dolphins left and known, with all of them considered to be endangered, and one, the Chinese Yangtze River Dolphin, actually thought to be extinct as they have not been sighted in a very long time.
Image source: smithsonianscience.si.edu