Scientists Unearth Fossil River Dolphin that Originally Lived in the Ocean

A group of scientists from the Smithsonian has unearthed the fossils of a new species of ‘river dolphin’ which initially lived in the ocean.

Researchers now hope that the new find may help them better understand how species migrate from one place to another when they are pressurized by a changing environment. Nowadays, cold-loving animals must leave their habitats and adapt to northern altitudes as global warming pushes temperatures further up.

The research team had to race against the tide when they performed the excavation but the findings were rewarding. A paper on the new discovery was published Tuesday in the journal Peer J. The dolphin was scientifically dubbed Isthminia panamensis and was found on a coast in Panama.

Researchers explained that the animal share many traits with modern-day river dolphins, so they may be remotely related. Currently, there are only four species of river dolphins that can survive outside captivity. Unfortunately, three of them are on the threatened species list including the Irrawaddy River Dolphin , while the forth, the Yangtze River Dolphin, was recently declared extinct.

But there are signs that the newly found river dolphin thrived in the sea. So, scientists speculate that the species originally lived in oceans, but as the place got crowded they decided to migrate to rivers. In the new environment they were able to survive due to their wide flippers, flexible necks, and elongated snouts.

The recent find challenges evolutionary theory which states that whales and dolphins evolved from land animals to amphibians to sea creatures, since the move of Isthminia panamensis is exactly backwards.

Isthminia panamensis is also important because it represents a common ancestor to both river dolphins and ocean-bound dolphins. Though its features suggest that it was perfectly adapted to living in a river, the place where it was excavated suggests that it had lived in the ocean. Additionally, its skull and jaw suggest that it was a sea creature.

Nevertheless, the team acknowledged that they are not sure that the newly found species is related to modern day river dolphins.

Nicholas D. Pyenson, senior author of the discovery and curator at Smithsonian’s National Museum of Natural History, explained that the new fossil provides scientists with new clues on how the river dolphin invaded Amazonia. Moreover, several other species in Amazonia had oceanic ancestors including stingrays and turtles.

Smithsonian scientists suspect the Isthminia was pushed into inland when the ocean levels started to rise. And that may happen again to many marine species with climate change and global sea levels rise, the group explained.

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