Saturday, November 22, 2014

Oryctodromeus exhibit at the Museum of the Rockies

After roughly a year of work the exhibit on Oryctodromeus, and aspects of the fauna and flora of the Wayan Formation of Idaho and Vaughn member of the Blackleaf Formation, is on public display at the Museum of the Rockies in Bozeman. Since my research includes providing a thorough osteological description of Oryctodromeus, I was asked to choose all the bones that were cast and molded for the skeletal mount, and to help make sure that the skeletal mount represented our best knowledge of the animal. Having worked on the animal for about a decade (collecting a lot of specimens before the species was described and describing the osteology of Idaho specimens in my Masters thesis), it is awesome to finally see a skeletal mount of the animal, and an exhibit describing some of the fauna and flora of the Wayan and Vaughn! I also love how the work of everyone involved in researching the Wayan and Blackleaf (Jamie Fearon, Steve Robison, Jade Simon, Cary Woodruff ) is described. Here I don't want to give away the whole exhibit, but I would like to share the Oryctodromeus mounts.

I love the Lull Mount that Matt Smith of Livingston did. A Lull Mount is a mount were one side is skeletal and the other side is fleshed out. Of course we have no idea about what integument Oryctodromeus had but I like the scheme used here. One of the things that took some people by surprise as the skeleton took shape is the length of the tail in Oryctodromeus. The tail on this mount is over seven feet long, roughly two-thirds of the whole length of the animal, a condition similar in Tenontosaurus. I based the length of the tail on a Wayan Formation specimen which represents (as far as I can tell) one individual, this specimen has 57 caudal vertebrae. I measured the length of each caudal and just used that to give a minimum length for a tail. Interestingly, the tail vertebrae of Oryctodromeus very quickly loose their long processes and the tail becomes thin and whip-like.
Another interesting aspect of the tail not indicated on the mount is the extreme abundance of ossified tendons found in many of the specimens. In these specimens the ossified tendons begin near the base of the neck and occur on the tops of the transverse processes of the vertebrae, and the tail vertebrae are entirely encased in a thick lattice of tendons (see Krumenacker, 2010). This could definitely complicate getting around in a burrow if these tendons were as stiffening as believed. But we have ideas that may help solve this problem...

Of course one of the most important aspects of Oryctodromeus, is it's burrowing behavior. As described originally (Varricchio et al., 2007), the bones of an adult and two juveniles were found in a fossilized burrow. Matt Smith did a great job again creating a replica of the burrow with two kiddos and the adult in the burrow. The original description also discusses smaller burrows that extend off the main body of the Oryctodromeus burrow, these could possibly belong to a small mammal (look carefully at the burrow in the exhibit).

As I said, I don't want to give away everything about the new exhibit, so I'll leave off there.

A few useful references as discussed above:

Krumenacker, L.J., 2010. Chronostratigraphy and paleontology of the mid-Cretaceous Wayan Formation of eastern Idaho, with a description of the first Oryctodromeus specimens from Idaho. BYU Provo MS.

Varricchio, D. J., A. J. Martin, and Y. Katsura. 2007. First trace and body fossil evidence of a burrowing, denning dinosaur. Proceedings of the Royal Society B: Biological Sciences 274: 1361–1368.

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