Bonnerichthys dig: October 2011

On our last field expedition to Logan County this fall, we intended to try and recover the remains of a large Clidastes specimen located by one of our ranchers. That critter turned out to be a bit of a bust, however about 18 inches below it, we noticed another chunk of bone sticking out of the outcrop. Tracing it in, we eventually figured out it was a pectoral fin of the giant filter-feeding fish Bonnerichthys gladius. These fish are pretty darn rare, and since myself and Mike Triebold were co-authors on the paper naming this fish, we were pretty happy to find it.

Jacob Jett's feet for scale. The orange paint marks where we cut the slab with a chain saw

Detail shot of the distinctive fin of this strange fish

The chalk was very hard, but we were lucky enough to have all of our fancy air tools along with us after helping Mike Everhart with his Protostega dig earlier that week. That made life so much easier on our crew.

Preparation begins, with my hand for scale

The dig lasted just a day, and unfortunately it was just pectoral fins (and a few radials) preserved, the most common bits of this critter found. The fins themselves were 3 feet long, indicating a fish in the 15-foot range. We brought the specimen back to the lab and prepared it in a few days. Now what do we do with it?

The most intact fin, after the cleaning is finished