.87" Juvenile Tyrannosaur Premax Partial Tooth - Judith River Fm.

Three species of tyrannosaur have been described from the Two Medicine & Judith River Formations: 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 genus because they are so similar.

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

The Judith River Formation is one of the world's most prolific sources of Late Cretaceous vertebrate fossils. At least sixteen Orders containing more than forty Genera are known from the formation. These include fish, amphibians, mammals, and insects in addition to reptiles and avian (birds) and non-avian dinosaurs. Among the more interesting specimens is Leonardo, a mummified and fossilized Brachylophosaurus. This is a hadrosaur, a duck-billed dinosaur found with amazing soft-tissue preservation: skin impressions can be found on 90 percent of its body! The pattern in the skin on its feet is even preserved. In addition to Leonardo, the Judith River Formation contains the remains of the theropod Hesperornis, the only known freshwater Hespernorthid, a penguin-like bird.