Uncovering the Secrets of Ancient Sea Monsters Through Jormungandr Walhallaensis

Thursday - November 2 2023, 14:23 UTC - 1 year ago

Paleontologists have uncovered a new species of mosasaur from North Dakota, named Jormungandr walhallaensis. This species is 24 feet long and possesses flippers, a shark-like tail, and an ‘angry eyebrows’ ridge on its head. It likely served as an ancestor to the larger Mosasaurus. This discovery is expected to better our understanding of the evolutionary relationships between various mosasaur groups.

Many millions of years ago, the Earth was home to remarkably diverse life forms that coexisted with colossal dinosaurs. The marine habitats were dominated by massive aquatic lizards known as mosasaurs, among the most powerful carnivores of their day. These marine reptiles existed between 80 and 66 million years ago, during the Late Cretaceous epoch. Paleontologists have now unearthed a new species of mosasaur from North Dakota. This new-to-science species has been named Jormungandr walhallaensis. According to the official release, the newly found species is named after the Norse mythology sea serpent called Jörmungandr, while Walhalla is the name of the place from where its fossil remains were unearthed. Examination of this nearly complete specimen revealed that it represents a previously unknown species.

Jormungandr's fossil bones were discovered in northwestern North Dakota in 2015. The specimen includes an almost complete skull, jaws, cervical spine, and several vertebrae. Analysis of the fossilized bones and surface scanning revealed that it represents a previously unknown species. The authors from the American Museum of Natural History also observed that the specimen shares several characteristics with two other mosasaurs, namely Clidastes and Mosasaurus. Clidastes, a smaller creature, measured roughly six to 13 feet in length and inhabited the Earth around 145 million years ago. In contrast, Mosasaurus was significantly larger, reaching lengths of nearly 50 feet, and existed in the period spanning about 99.6 to 66 million years ago alongside T rex.

This newfound specimen is roughly 24 feet long and possesses flippers. "If you put flippers on a Komodo dragon and made it big, that’s basically what it would have looked like," said the study’s lead author, Amelia Zietlow. The spectacular fossil remnants also show the presence of a shark-like tail, similar to those found in other early mosasaur species. Furthermore, this species likely possessed distinguishing traits such as "angry eyebrows," generated by a bony ridge on its head. Its tail would have been small and stubby compared to the rest of its body. The authors theorize that Jormungandr was probably an ancestor or precursor to the larger Mosasaurus. These findings hold significance in understanding the evolutionary relationships among various mosasaur groups.

Many questions about mosasaur remain unanswered. The first mosasaur discoveries stretch back over two centuries, with the term "mosasaur" appearing around two decades before the word "dinosaur." Mosasaurs lived on Earth roughly 100 to 66 million years ago, eventually becoming extinct alongside non-avian dinosaurs due to a cataclysmic asteroid collision. Numerous unanswered questions persist regarding this marine reptile group, such as the frequency of flipper evolution and the transition to complete aquatic lifestyles, as well as their exact evolutionary relationships, such as whether they are more closely related to monitor lizards or snakes.

"As these animals evolved into these giant sea monsters, they were constantly making changes," Zietlow said. "This work gets us one step closer to understanding how all thse pieces fit together into the big picture." .