Judith River Formation, Montana Theropod Tooth Identification

[Joseph Kapler]

As I understand it there are three described Tyrannosaurs from the Two Medicine and Judith River Formations -- Albertosaurus, Gorgosaurus and Daspletosaurus.  I have read that research done on teeth from these three Tyrannosaurs has concluded that isolated teeth are statistically impossible to assign to a specific genus because they are so similar.  Now, I know that there are a number of form members that have quite extensive collections and have spent time and money studying these teeth, and it is my believe (having spent 35 years in the minerals exploration business) that private researchers probably know as much if not more than the academics.  It has been my experience that academics rarely spend their own nickel buying their own equipment, conducting field work, and collecting specimens to conduct their research. I also know from first-hand experience that  statistical evaluation alone can lead one down the wrong path and to the conclusion 'it needs more study.'  While I am not a 'true' collector, my interests are hands-on fossil and mineral specimens that tell a story to interest kids in general science.  My question is are there any general observations about Two Medicine and Judith River Formation theropod teeth that one might use to assign a probable genus to these teeth?  It seems that assigning a genus to isolated teeth from the large adult theropods is quite possible, juvenile teeth seem more problematic -- but juvenile teeth are what I can afford.  I would appreciate observations you might be willing to share.

[Troodon]

There are no Tyrannosaurids officially described in the Judith River Formation and Albertosaurus is only known from the Horseshoe Canyon Fm of Alberta.   So, we cannot assign any teeth to a genus until something is described and those under study may wind up being assigned to Thanatotheristes.  these teeth should currently be called indeterminate tyrannosaurids

 

Here is a guide I put together to help 

Can You Identify Tyrannosaurid Teeth From North America? - General Fossil Discussion - The Fossil Forum