Tuesday, 9 September 2014

North American Summer

As I mentioned previously, my summer was billed to be a pretty busy time, and indeed it was. I am now back in the UK, and back at work, but I'll talk a bit about my trip to North America looking at pterosaurs and digging for dinosaurs.

My trip to North America started out in Los Angeles, where I spent 4 days working at the LA County Museum of Natural History (LACM) with one of my supervisors, Mike Habib. I had a great week looking through material, mainly of Pteranodon, but also some casts of Pterodaustro, and a Nyctosaurus. The museum has a decent amount of material, including part of a very large skull which is on display, and also a few partial or nearly complete wings, which I really enjoyed. I also was fortunate to have arrived just after they had prepared a new specimen (I say new, but they actually received it in the '60s, but it was only recently opened up and prepared), which was very exciting. It was a really cool specimen, but I am not sure if I'm allowed to talk about it too much yet, so maybe later. We spent a lot of time looking at the wings for evidence of pneumaticity, which is one of my interests as you will know if you've read my previous posts. Unfortunately, as many of you may know, Pteranodon and Nyctosaurus are both almost completely flattened, which means that finding pneumatic foramina can be extremely difficult.
Pteranodon display at the LACM. Note the absolutely massive partial skull on the bottom right.
I also got to go to the Page Museum where the La Brea tar pits are, and got to go behind the barriers and see some material actually being excavated which was pretty cool. Probably my favourite part of that museum was looking at the birds, particularly the teratorns, that have come out of the tar pits. Standing there for some time while Mike pointed out features like pneumatic foramina, the tank-like nature of the teratorns, and other cool things was a big highlight for me.
Not a great picture, but here's a complete skeleton of a Teratornis at the Page Museum. I was amazed by the tank-like stature of it compared to more typical gracile birds.
The best part of the summer for me was spent doing 2 weeks of field work in Alberta, Canada, near Grande Prairie, where I got to work on a dig with Phil Currie's lab, in conjunction with the 'soon-to-be-open' Philip J. Currie Dinosaur Museum. We were working mainly at the Pipestone Creek bone bed, which is an almost completely monotaxic (one group of animals) Pachyrhinosaurus bone bed located near the town of Wembley. This site is 73 million years old, and may represent the most abundant bone bed from the Late Cretaceous (or one of the most fossiliferous bone beds anywhere!), with between 30-100 bones found per square metre! While only a small portion has been excavated to date, it's estimated that the bone bed takes up over two football (American football) fields in size. It's likely that over 1000 Pachyrhinosaurus (a ceratopsian dinosaur distantly related to Triceratops) died here, possibly in a flood. While over 99% of the bones found here are Pachyrhinosaurus, there are tyrannosaur teeth, and very rarely some theropod bones.
The area of the bone bed we exposed this summer was found underneath the tarp, which we laid down each night to keep it dry. You can see the massive hill behind that we had to climb with our buckets of matrix (dirt/rock) after uncovering the fossils.
Palaeontologists and volunteers hard at work uncovering Pachyrhinosaurus fossils.
The bones found here are all disarticulated and jumbled up, rather than nicely articulated, complete skeletons. This indicates that the skeletons were broken apart before buried and fossilised. The animals were likely scavenged by large and small predators alike as their bodies rotted and the carcasses lay exposed after dying after the flood. The large number of shed tyrannosaur teeth indicates this, as tyrannosaurs like Albertosaurus lost and replaced their teeth constantly, like modern sharks.

This site was initially excavated by the Royal Tyrrell Museum of Palaeontology in the 80s when Phil Currie was still working there after being told about the site in the 70s. After moving to the University of Alberta, he realised that the remains represented a new species of Pachyrhinosaurus, and named it Pachyrhinosaurus lakustai, after the science teacher (Al Lakusta) that found the site. Dr. Currie and the U of A team have continued to work at this site each summer. Now that a permanent palaeontology museum with palaeontologists like Matthew Vavrek has started up in the area, the U of A team will likely scaled down their work there and let the new museum take over. While it has been worked on for many years, there is still lots of new information coming out of the bone bed, and lots to be learned!
Some Pachyrhinosaurus fossils as they were being uncovered. The large top one near the feet is a fairly complete rib that continued to go underneath several other bones which can barely be made out.
The grid square - an important palaeontological tool. This allows for all bones found to be mapped so the orientation can be analysed later. This allows us to better understand patterns in orientation related to things like palaeo-river flow.
I was also able to spend some time at another bone bed that is found along the Wapiti River. This site is much smaller, and located on the side of a cliff/steep hill, which poses some interesting problems with access and specimen collection. The material found here is interesting though because while it is Pachyrhinosaurus, it's unclear exactly what species it is, since the material is found in extremely hard and difficult to prepare iron nodules. This makes it challenging to figure out exactly what is going on, as it may not represent the same time period as the Pipestone Creek bone bed.
The Wapiti River bone bed - what a wonderful view!
Another fun thing about being there when I was, was it was the official ribbon cutting ceremony of the Philip J. Currie Dinosaur Museum, named for my old supervisor that I was doing field work. This meant that we were host to a number of celebrities over the final week, including Dan Aykroyd and family, Fran Drescher, and the Canadian Tenors. We also got to go to the Dinosaur Ball, which is an annual event to raise money for the museum.
Some of us and Dan Aykroyd! I'm on the right