That week seemed to fly by, but looking back, it was really productive. I was able to get a lot of work done in the lab, and saw some fantastic specimens for the first time. I forgot to add an update on my work in town last time, so there will be a bit more here. It fits well because unfortunately we were rained out for most of our short time at Bugiin Tsav.
Note: This is week three of my series documenting my trip in Mongolia. Check out week 1 and week 2 if you missed them.
On August 23rd, the Kamaz (a huge, Russian, 6-wheel drive truck) came to pick up the jackets we made from the dream quarry in Guriliin Tsav. We had a lunch in camp, and then packed up and moved 30 minutes away to Bugiin Tsav. Bugiin Tsav is kind of like the ‘big brother’ of Guriliin Tsav, and it’s truly a wonderland for fossils. Some of the best finds from the Gobi have come from this locality, including a baby Tarbosaurus, the unusual dromaeosaur Adasaurus, and a skeleton of Deinocheirus that helped to clarify just what this weirdo looked like.
We arrived mid-afternoon, and I was immediately struck by how BIG Bugiin Tsav is. Scouting on Google Maps did not do the site justice. We drove to the southern end of the exposures, where a crew from Okayama University of Science was camped. We just happened to arrive on the last day for most of their crew, so we had a joint dinner and partied until the wee hours of the night. The next morning, most of their crew left, and the remainder joined our expedition.
Bugiin Tsav has produced dozens of incredible oviraptorid specimens, but one in particular is more interesting for me: Nomingia gobiensis. This is an enigmatic oviraptorosaur known solely from the dorsal vertebrae, the pelvis, part of the hindlimb, and a complete tail–tipped with the first pygostyle known in a dinosaur. Despite the importance of the specimen, there are some issues with its relationships to other oviraptorosaurs. When it was initially described, Barsbold et al. (2000) figured that it was probably a caenagnathid, but very little was known about caenagnathids at that point. Then, when Lamanna et al. (2014) described Anzu wyliei, their phylogeny had a surprise: Nomingia came out as an oviraptorid, rather than a caenagnathid. I addressed this issue more in our 2018 paper in the Nemegt Special Issue, but I wanted to visit the quarry and see if any more material had eroded out.
I didn’t find anything from the Nomingia site, but a couple metres away I found some other theropod bones. Most of the material had eroded down the hill, and it seemed mismatched for size–there were probably two different taxa in a mixed-faunal bonebed. I collected a beautifully-preserved femur and a nice claw, both of which are probably from a dromaeosaur.
Unfortunately, we were rained out the rest of the day. It cleared up in the evening and we had a beautiful rainbow, but we weren’t able to do too much in Bugiin Tsav. The next day we packed up and went back to Nemegt.
Back at the lab…
I’ve been working the past two weeks on finishing up a couple projects, and, against my better judgement, maybe starting a few as well. I’ve been looking at two main specimens, MPC-D 102/11, and MPC-D 102/12. These are two specimens that belong to a new species of oviraptorid. Unfortunately, MPC-D 102/11 and another specimen are poached, so we don’t know where exactly they’re from. I was able to collect the last bits of data I need before I can publish the study, which we’re hoping to do soon. This included some thin sections, which help to show that these individuals represent an ontogenetic series: MPC-D 102/11 is just over one year old, MPC-D 102/12 is a 5+-year old adult.
I also had the opportunity to look at some oviraptorid embryos collected from Bugiin Tsav that have been previously described. I think I may be able to eke a little bit more information from them, specifically which taxon they represent. This would let us better understand growth in oviraptorids and see what changes we can expect as the animals grow up.
I also started preparing part of the dream quarry material, and it’s amazingly preserved. More to come soon, I hope… but again, here’s a flythrough of Bugiin Tsav instead.
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