Monday, November 28, 2011

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

Friday, November 18, 2011

Daspletosaurus prep update

Jacob and I have been hammering away at the remaining small jackets of Pete III. By small I mean things less than the 4 ton main jacket monstrosity that we'll eventually have to confront. This week we've finished the left femur and ilium, along with a slew of gastral elements, vertebrae, and other bits and pieces.

Anterior dorsal of Pete III compared to Stan
The ilium has a strange mass of punky bone on the medial face of the pubic peduncle. We've seen a few instances of old age related pathology on this specimen, it wouldn't surprise me to find more.

Medial surface of left ilium, 42 inches long

Before long, we'll be started on the pathological tail section. Can't wait!

Caudal view of left femur.

Friday, November 11, 2011

Daspletosaurus prep restarts: this time with skull bones

While I was away soaking up pathogens at SVP in Las Vegas last week, paleotech Jacob Jett has been busy preparing some of the jackets from the weathered edge of Pete III's excavation. The bone was in difficult shape to begin with (earning the nickname "The pixelated Tyrannosaur" at SVP) before seeing several hundred Montana freeze-thaw cycles, making this prep work one of our greatest challenges to date. However, results are here! Skull bones so far include both quadrates, a jugal, both quadratojugals, a spenial, pterygoid and possible surangular, with more to come. No toothy bits yet though.

The left quadrate. Actually recognizable!

Dorsal vertebra #1, giving you an idea of the sheer size of Pete III. Transverse process span is 15 inches (38cm)

Surprise! Manual phalanx!
We still have many jackets (including the majority of the big 4-ton monstrosity) to prepare, however we're confident that the majority of the skeleton and perhaps 20-30% of the skull is here. Check back for more updates!