Friday, April 12, 2013

Stangerochampsa: Weird Hell Creek Croc

Last thanksgiving when I was in Illinois visiting family, I got to take a day to visit the Burpee Museum in Rockford, IL. While there I got to pick up molds and original bones from one of their discoveries from the Hell Creek Formation of eastern Montana. Ernie is a small alligatoroid, apparently related to the much more common Brachychampsa. I never seem to be able to complete any vacation without becoming some sot of fossil transporter, however it gives me a chance to see a lot of new places along the way.

In any case, we've spent the past few months working on the specimen. It was pretty complete as far as Hell Creek crocs go (which isn't saying much, though if you saw the poster on the specimen at SVP last year, you have a pretty good idea) but it needed some parts badly.

Skull bones getting molded
The first thing we did was remold the individual skull bones and any other originals. Using the molds provided by Burpee we poured casts of the postcranial elements as well. In the end we had a nice skull and less than half of a body. How do we improve on that?

Donor gator, tail skilfully removed for shipping
Donor gator of course! Dr. Ray Wilhite from Auburn University was able to get us a 49 inch long frozen Alligator mississippiensis. It was a great day in the lab when the package arrived, not even oozing at all! Jacob and I did a dissection on it to see how things move on recent animals, then stripped most of the muscles and skin off of it before sending it to the dermestid beetle colony for final cleaning. The skin, especially the osteoderms were a lot more difficult to remove than we had originally planned.
Processing through, those jaw muscles give me nightmares

While the beetles were chewing away at the smelliest part of the gator, Jacob restored the missing bits of the casts of the original material. Missing neural spines and transverse processes were sculpted. When we got the modern bones back, they were disassembled and molded. Where possible we incorporated any part of Ernie into the restored bones.
Ernie's coming for you!
I especially like the shadow

Once remolded, assembly was pretty straightforward. The prototype was completed this week and will be headed back to Rockford for display in the upcoming brand new "Homer's Odyssey" exhibit in a very shortly!

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