Swimming in the cold water off the coast of Alaska may be a far cry from the warm , muddy waters of the Ganges River in India and Bangladesh , but research worker have found a curious connectedness between an ancient and mod species of mahimahi . Buried in the collection of the Smithsonian Museum for over half a one C , the skull of an ancient dolphin that survive in Alaska 25 million yr ago might provide a glimpse into the evolution of a dolphin that still cling on in South Asia .
The newly place fossil ( which you canplay with in 3D here ) could give aninsightinto the evolution of the South Asiatic river dolphin ( Platanista gangetica ) . “ One of the most utilitarian ways we can studyPlatanistais by canvas its evolutionary history , by looking at fossils that are related to it to attempt to get a good sense of where it ’s occur from,”saysAlexandra Boersma , one of the two investigator draw the fogey inPeerJ. From this , they could render and sympathize what do the once diverse and widespread grouping of marine mammals to dwindle to just the single specie that exists today .
The fogey comes froma clock time when it ’s thought the two major groups of dolphin and heavyweight project today – toothed hulk and baleen whale – first depart . All endure cetaceans fall into one of these chemical group , with the larger of the bunch , such as the blue whale , typically belong to to the baleen group , and the small dolphins being toothed ( though , as always , there are a few outliers ) . By comparing the skull , which has been given the species nameAkrtocara yakataga , with other dolphin species both alert and dead , they have square off that it ’s an ancient congenator of the South Asiatic river dolphinfish .
The South Asiatic river dolphinfish , which is divided into two subspecies – one of which lives primarily in the Ganges and Brahmaputra Rivers and the other that is find mainly in the Indus River – are strange beasts . uncommon , closemouthed , and dwell in large mucky rivers , not much is known about them except that they tend to float on their side , have no genus Lens in their eyes ( making them effectively blind ) , and rely almost entirely on echo sounding .
One affair that is certain , however , is that they are in need of pressing assistance . As the last living decedents of a descent of nautical dolphins , the evolutionarily distinct mammals are heading towards quenching . But in a way , that take the latest uncovering even more perplexing . “ Considering the only live dolphin in this group is restricted to fresh water systems in Southeast Asia , to find a congeneric that was all the way up in Alaska 25 million long time ago was kind of nous - boggling,”saysBoersma .
Image in text : Artistic Reconstruction Period of a pod ofArktocara yakataga . Linocut photographic print art by Alexandra Boersma
