Monday, October 30, 2023

Walhalla's Sea Snake: Welcome Jormungandr!

Believe it or not, I don't spend all of my time in the field (though it still does tend to be A LOT). In the winter and spring I have time to work on some fossils we find during the year, as well as work on projects for other museums. This past spring, Dr. Clint Boyd approached us about restoring a brand new mosasaur that he and a crew were describing from northeastern North Dakota. He called the critter "Eustace", nicknamed after the BEST character from the Cartoon Network classic "Courage the Cowardly Dog".

Eustace is famous for various disagreements

The specimen was found in the Pembina member of the Pierre Shale and an underlying bentonite was dated to 80 million years old. This is pretty similar in age to our "Walker" Mosasaurus specimen that we excavated from Western Kansas in 2015. I suspected we were in for a very fun project, and something that we at TPI are very capable of doing well.

Walker's reconstructed skeleton

The first step was getting the scan files of the specimen sent over and opened up in the computer. The specimen was fairly complete but missing a few bones. Evan Sonnenberg and I teamed up to reassemble the parts, and remove some of the distortion to make the individual elements fit back together like before they were crushed by 80 million years of rock and geologic processes. Some elements were completed using mirror images of bones from the opposite side of the skull in order to keep Eustace as Eustace as possible. 

Eustace's skull (right) and after restoration (left)

Once that part was completed, we used mosasaur specimens from our digital bone bank to come up with plausible shapes for the bones that were completely missing. When working on the parietal/braincase, lead author Amelia Zietlow kept urging us to make it more Clidastes-ey in overall appearance. And indeed, the paper that came out today does make a case for the new mosasaur being very closely related to Clidastes. Amelia and crew decided to name the specimen Jormungander walhallensis, which is a pretty clever name. The species name indicated it came from near Walhalla, ND, while the genus name plays off of the Norse mythology of the place name, with the name shared with the legendary snake that ends the world in the sagas. 

Once all the parts were there, we printed out two copies of the skull at full size so that they could go on display in museums in North Dakota. While not a huge mosasaur like the Bunker Tylosaurus, the skulls still had to be printed in pieces that were later assembled.

Parts for the top of the skull

Top of skull assembled

Easy enough! Lastly the specimens needed to be painted mounted. There's an external steel armature under the skull and each lower jaw on the copies so that the parts can be removed for closer inspection. One Easter egg that we included in the mount was that each base is a silhouette of Eustace's skull as seen from above. BTW the mini skulls were sent to the authors so they could evaluate it while finishing the manuscript.

The two reproductions were sent to North Dakota this June. One is on display at the Walhalla Library, which is nice having it on display so close to where the original specimen was discovered. The second is due to go on display at the Pembina State Museum in the near future.

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