Wednesday, February 27, 2013

Our own "Project Daspletosaurus"

There has been a fair bit of blog hype recently regarding Dave Hone's fundraising project to study cannibalism in tyrannosaurs. BTW if you feel like kicking in a few bucks, you can do so here. In short, they've observed tyrannosaurs in Alberta that seem to have been eaten by other tyrannosaurs. Neat.

Special thanks to Henry Mendoza for helping sort this drawer of teeth
It got me thinking: "Gee this sounds really familiar, where have I seen this before? Oh right, in these drawers right behind my desk!".  TPI fieldcrews recovered an 11m (35 foot) long Daspletosaurus specimen in 2003 from the lower Judith River Formation of Petroleum Co., Montana. This specimen, known as BCT or "Sir William" was originally thought to be a juvenile Tyrannosaurus rex based off of it's surprisingly low dental tooth count (only 13, Daspletosaurus should have 18-ish) and because of a field stratigraphic error (the rock unit was marked as Hell Creek Fm on some older geologic maps).
Small through large shed teeth from the site

The specimen was recovered in a very hard sandstone and much of it was encased in ironstone concretions. Preparation was difficulty but something stood out: The huge number of shed tyrannosaur teeth mixed in with the main specimen. A whopping 52 teeth from various sized tyrannosaurs shed at this site, in addition to several other rooted teeth that are definitely from BCT.
An example of the big teeth from BCT

So what does this mean? Well, it's another data point that goes a way to confirm the hypothesis, plus we can show that it happened in other geographic areas and with possibly different species of Daspletosaurus (I'm confident that BCT is NOT Daspletosaurus torosus). Plus, in the end, tyrannosaur teeth are just neat.