Digging a tyrannobutt

We're back from Montana waiting for the temperatures and fire danger to die down for a bit. Earlier this month though we were battling the gnats working on excavating a dinosaur I found late last summer.

Can you spot the site?

The site is pretty typical for how I find them: about halfway up a 30 foot cliff with a menacing hoodoo overhanging the specimen. I found this site about 2 days before we broke camp last year so I was only able to do the smallest of evaluation digs on it.

Bones on either side of an erosional notch: usually a good sign

 Using air tools I was able to notch out a few of the bones. These were clearly large theropod bones, one looked like a caudal vertebra and I couldn't tell what the one shooting straight into the cliff was. Big theropod in the Judith River formation means one thing: Tyrannosaur! I knew I'd be coming back for this site in 2017.

Duckbills. It had to be duckbills

Additionally at this site was a big wad of predepositionally broken ornithischian (most likely duckbill) bones under the tyrannosaur material. This gave the impression of a stream or oxbow lake bottom assemblage, but sometimes you find good skeletons mixed in with all this material. Unfortunately with fall closing in, I had to abandon the site till 2017.

Storms are no fun in vehicles that lack roofs and windshields

This year however we came out with our big jackhammer and managed to notch out a decent sized evaluation pit. I wanted to get a better feeling for what was present before I suggested getting a bulldozer out there to knock down the whole cliff.

The isolated tyrannobutt

Turns out, it appears it was just an isolated tyrannosaur sacrum with one dorsal vertebra still attached. Not pretty now, but once I prepare it we will see better the shape of the specimen. I'm thinking Albertosaurus, but it's hard to say from this element.

Closeup of the spines. Bonus duckbill chevron at top left

It's a bit of a bummer that there wasn't more of this skeleton. It was going in towards the head but it was just not meant to be. I'm happy to find this now before we invested time and resources removing 15 feet of really tough sandstone from the area though. Guess I'll just have to spend the rest of my summer looking for more dinosaurs. It's a tough job but somebody's got to do it!

The Accidental Ichthyornis

Field identifications are problematic.

In mid October of this year the weather in Kansas was still warm enough to extend our dig season. That trip was pretty successful, finding a back half of a Protosphyraena and several small fish. Early on, Mike even thought he found another Pteranodon leg.

The drive to the site is a lot tougher when you can't see landmarks

We came out early in the morning. Man was it foggy. The entire day was supposed to be dedicated to finishing up excavation at several small sites. Since the "Pteranodon leg" site was so small, Mike and Jacob spearheaded the excavation there, while I wandered off to collect a Cimolichthys head and isolated Ichthyodectes site.

Several bones coming out at the site as discovered. Definitely not fish.

The "Pteranodon leg" showed some promising chunks of bone coming out, however inspection as they got down to the bone layer showed not a whole lot was there. Not like the large bones we were hoping to find for a Pterosaur.

That's a big hole for such a little block

Not a huge worry though, we perimeter the sites and very rarely expose the bone in the field, we will just find out what the "Pteranodon leg" looks like when we get back to the lab.

Jacob jackets and despairs as I tell him we have to go dig up another fish

Looking back at the video, just as Jacob began jacketing the specimen, I show up back at the site proudly announcing the discovery of the "Nia" Xiphactinus site that I blogged about last time. We all decided to drive over to the big fish and start work as the jacket cured. We were so stoked about the big fish that it was about a month later when we finally asked ourselves "Hey! Where did that jacket go?"

Turns out, we left it sitting there in the field, right next to a regularly visited oil well. Whoops! Over Christmas, Mike returned to the site to see if someone had poached it. Nope, the jacket was still exactly where we had left it. I guess you can say we got dang lucky. Let's never do that again.

Mike pulled it out and brought it back to the lab, where it sat for a week as I let it dry out (dry chalk behaves better than wet stuff when prepping, especially with small fossils). That's when the Eureka Moment happened: prepping down on the "Pteranodon leg" things weren't looking right. I immediately switched to my microscope, pin vise and very low pressure air abrasion (about 3psi with sodium bicarbonate blast media). My suspicions on the specimen's identity were confirmed when I found teeth. Pteranodon doesn't have teeth, but there's one small thing in the chalk with reptile-textured bone that does have it: a bird! Not only was it a bird, but the only complete articulated skull of Ichthyornis, who had been found only in fairly incomplete form since Marsh's days in the 1870s. This accidental and overlooked jacket suddenly turned into one of the rarest finds in the entire 160 year history of fossil hunting in the Niobrara.

Bird teeth, just a few milimeters long

Stay tuned for project updates as we work on this spectacular fossil.