1.13" Tyrannosaur (Aublysodon) Premax Tooth - Montana

This is a very interesting Tyrannosaurid tooth from the Two Medicine Formation (Judith River Group) of Montana. This Formation is about 5 million years older than the Hell Creek Formation where T-Rex comes from. This tooth has smooth, beautifully preserved enamel with some weathering in a few areas and feeding wear to the tip and edges. It has no repairs or restoration.

These oddly shaped teeth with two ridges located on the lingual side where originally described as Aublysodon more than a century ago based off of isolated teeth and jaw fragments. More recent discoveries of more complete Tyrannosaur skeletons from this formation has lead to the discovery that these teeth are actually the premaxillary teeth of other Tyrannosaur species.

There are three described Tyrannosaurs from the Two Medicine Formation (Judith River Group), Albertosaurus, Gorgosaurus and Daspletosaurus. Research done on teeth from these three Tyrannosaurs has concluded that isolated teeth are statistically impossible to assign to a specific genre because they are so similar. This means the best we can do on identification is this is a premax tooth of one of these Tyrannosaurs. I've linked to the research paper below.

Morphometry of the teeth of western North American tyrannosaurids and its applicability to quantitative classification