Monday, August 1, 2016

Digging up our Triceratops: Count Trikeula!

This rather small rainstorm blew north of us
Photo: J. WIlson

Why not begin with a bit of rain?

Our first week in the field started with quite a lot of rain. This can be a real problem for fieldwork out on the prairie as the dirt roads quickly absorb the rain and become an impassable mire. Even if you are able to drive through the mud, you can leave huge ruts that can damage the roads in the long term. In these situations it's smarter to sit tight and wait out the weather: you can't dig bones in the rain anyway.

I had wanted to start our season at "Count Trikeula": a decent-looking Triceratops skull site discovered by crew member Danny Anduza last year. However, Count Trikeula is not immediately accessible in bad weather. As such, we've been jumping about among 3 main sites, hitting Count Trikeula when we can, and heading to some more accessible sites when that wasn't possible. On the blog, I'm going to talk about the sites individually so we're going to start with Count Trikeula.

Triceratops sp.. Drawing: D. Anduza.

'Count Trikeula' 

This is a site that we had exposed a little bit last year. Count Trikeula is a 3/4 grown Triceratops, which is fairly average size for a Triceratops, but still a very big animal! 

In 2015 we could see that Count Trikeula  had a good-looking frill at the back of the skull, but we couldn't tell how much of the skull and skeleton might be there as our permit only allowed us to dig a fairly small hole.

In 2015 we could see the rear edge of the frill, and the cheek spike
Art: D. Anduza

Cue 2016 and our excavation permit! We spent a half day clearing overburden, then dug in around the skull.

2016: Hell Creek rocks are not particularly hard so you usually only need hand tools to remove overburden.
Photo: Kit Robison
After the overburden was done, we peeled away the protective tarp and cover we had placed over the site in 2015.
Photo: Kit Robison

Once the overburden was completed, we set up a shade tarp and started digging!
Photo: D. Fowler

It became apparent rather quickly that the front of the face had been damaged before the skull had been buried, 67 million years ago. This was a shame as I was hoping that this site might give us a new datapoint for ongoing research on how Triceratops evolves through the Hell Creek Formation. 

In 2014, I coauthored a research paper which described how Triceratops skulls collected from low in the Hell Creek Formation have a small nose horn and belong to the species Triceratops horridus; whereas skulls found in the upper part of the formation have large nose horns and belong to Triceratops prorsus. The skull of Count Trikeula is low in the Hell Creek, so it should have a small nose horn, but sadly it doesn't seem to be preserved.

Our digging revealed the back of the skull is quite complete, but the face is mostly broken away.
Photo: H. Flora

Schematic showing which parts of the skull were well preserved.

The frill of Count Trikeula is much more wide than we typically see in Triceratops prorsus, suggesting that it does not belong to that species. Also, the bases of the brow horns are wide and robust. This is supportive of Count Trikeula belonging to Triceratops horridus, but we will need to clean all the bones back in the lab to test this hypothesis properly.

Count Trikeula has a 70% complete parietal bone (middle of the frill) which is actually quite rarely preserved in Triceratops. It also has a injured squamosal (corner of the frill). These features make Count Trikeula a good specimen to help in our research on Triceratops evolution and behavior.

The right squamosal of Count Trikeula has rough bony growths on the surface, indicating an injury that occurred during life
Photo: D. Fowler
Okay, that's it for this blog post. We're continuing to work at Count Trikeula when weather permits, but the next blog post will be about one of out other sites!



PS. If you're in Malta, MT, stop by the Great Plains Dinosaur Museum to see some of our latest finds temporarily on display until we head back to Dickinson ND.

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