This ancient sea creature roamed the waters above North Dakota

In Norse mythology, a monstrous sea serpent wrapped itself around the waters of the world. The name was Jormungandr.

The ancient Norsemen also believed in a place called Valhalla or heaven. And in North Dakota there is a small town called Walhalla, a name that reflects the area’s Scandinavian heritage.

It was near there that a new species of mosasaur, a type of giant sea animal, was discovered, scientists announced last week. They called it Jormungandr walhallaensis.

Jormungandr walhallaensis, which lived about 80 million years ago, is considered a new species and genus of mosasaur, an ancient lineage of marine reptilian predators that lived in Earth’s waters almost 100 million years ago.

“There are a lot of papers about dinosaurs published every year, but there aren’t many papers about mosasaurs published every year because there just aren’t very many people in the world working on them,” says Michael Caldwell, a leading mosasaur expert and biological researcher. science professor at the University of Alberta in Canada, who did not work on the discovery.

Mosasaurs were essentially giant lizards with fins that allowed them to live in the sea, with some species growing up to 60 feet.

They became extinct at the same time as the dinosaurs.

Amelia Zietlow, a doctoral candidate at the Richard Gilder Graduate School of the American Museum of Natural History and the lead author of the new study, said Jormungandr walhallaensis carries a unique mix of physiological traits from what is perhaps the best-known genus of mosasaur, the school bus size mosasaur (pictured, however large, in the movie “Jurassic World”) and its smaller, more primitive predecessor, the clidastes.

An analysis performed by computer software failed to produce an exact match for the fossil in the mosasaur fossil record, leading Ms. Zietlow and her co-authors to conclude that their fossil was not just a new species, but an entirely new genus located somewhere between clidastes. and mosasaur in the mosasaur lineage.

However, there is a healthy debate on this point.

“Do I necessarily agree that it is a new genus and species?” said dr. Caldwell. “Well, no, I don’t. But those are a bit of scientific quibbles, aren’t they?

It’s more likely, said Dr. Caldwell, that the fossil described in the study is simply a new species of the genus Clidastes. According to this view, it would adopt the name Clidastes walhallaensis.

Still, the paper adds “extremely valuable” data for future research as the field evolves into what is still a fledgling understanding of mosasaur evolution, said Dr. Caldwell.

Although Ms. Zietlow and her co-authors only had to analyze the skull and jaw of Jormungandr walhallaensis, they were able to gather important details about how the animal lived and died.

Jormungandr walhallaensis was probably 5 to 7 meters long, Ms Zietlow said.

The shape of its teeth indicates that it hunted fish and other small creatures as it prowled the Western Interior Seaway, which split North America in half through the Midwestern states during the late Cretaceous period.

Some of the animal’s vertebrae show teeth marks that appear unhealed, Ms. Zietlow said, suggesting the animal had been attacked by another animal, possibly even another mosasaur, not long before it died.

The fact that the rest of the skeleton was missing when it was discovered suggests that it may have been eaten.

Ms Zietlow hopes her work on Jormungandr walhallaensis will spark interest in mosasaurs, which she says have been little studied despite collections of their fossils in museums across the continent.

“Of the 4,000 mosasaurs in North America,” Ms. Zietlow explained, “only about 5 percent have been recorded in the scientific literature.”