New Mosasaur Found in North Dakota: Jormungandr Walhallaensis

In Norse mythology, a monstrous sea serpent coils around the waters of the world. Her name was Jörmungandr.

The ancient Norsemen also believed in a place called Valhalla, or Heaven. In North Dakota, there is a small town called Walhalla, a name that reflects the Scandinavian heritage of the region.

Nearby, a new species of mosasaur, a type of giant sea creature, was discovered, scientists announced last week. They called it Jormungandr walhallaensis.

Jormungandr walhallaensis, which lived about 80 million years ago, is a new species and genus of mosasaurs, an ancient lineage of predatory marine reptiles that inhabited Earth’s waters nearly 100 million years ago.

“There are a lot of papers published on dinosaurs every year, but there aren’t a lot of papers published on dinosaurs every year because there aren’t a lot of people in the world working on them,” said Michael Caldwell, a leading mosasaurus expert and biologist. A 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 reaching 60 feet in size.

They became extinct at the same time as the dinosaurs.

Jörmungandr and halenensis bears a unique combination of physiological traits from perhaps the most famous mosasaurid genus, the school, said Amelia Zietlow, a doctoral student at the Richard Gilder Graduate School of Science at the American Museum of Natural History and lead author of the new study. -Bus size Mosasaurus (It was filmed, despite its large size, in The movie “Jurassic World”) and its smaller, more primitive predecessor, clidastes.

Analysis by a computer program yielded no exact match to the fossil in the mosasaurus 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 in between the rock groups. The mosasaurus is in mosasaur proportions.

However, there is a healthy debate on this point.

“Do I necessarily agree that it is a new sex and gender?” Dr. Caldwell said. “Well, no, I don’t. But that’s kind of a scientific quirk, isn’t it?”

Dr. Caldwell said it was more likely that the fossil described in the study was simply a new species of the genus clidastes. Under this view, it would take the name Clidastes walhallaensis.

However, the study adds “extremely valuable” data for future research to consider as the field develops what is still an emerging understanding of mosasaurus evolution, Dr. Caldwell said.

Although Ms. Zietlow and her colleagues only had the skull and jaw of Jörmungandr Valhallensis to analyse, they were able to obtain important details about how he lived and died.

Jörmungandr and halenensis may have been 18 to 24 feet tall, Zitlow said.

The shape of its teeth suggests that it fed on fish and other small creatures as it roamed the Western Interior Sea Route, which split North America in half across the Midwestern states during the Late Cretaceous.

Zitlow said some of the animal’s vertebrae showed signs of teeth that appeared to be unhealed, indicating that it had been attacked by another animal, perhaps even another mosasaur, shortly before its death.

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

Ms Zitlow hopes her work on Jormungandr walhallaensis will spark interest in mosasaurs, which she describes as understudied despite collections of their fossils in museums across the continent.

“Of the 4,000 mosasaurs in North America, only about 5% are listed in the scientific literature,” Ms. Zitlow explained.