Troodon formosus
Late Cretaceous
Hell Creek Formation
Harding County, South Dakota, USA

10mm theropod tooth. Rare.

Troodon belongs to the family Troodontidae, which is a group of small, bird-like theropod dinosaurs. It is closely related to other dinosaurs such as Stenonychosaurus and Zanabazar. Troodontids are thought to be closely related to birds and are often considered some of the most bird-like non-avian dinosaurs. Considerable debate exists as to the exact classification of Troodon and how many genera existed in North America at the end of the Cretaceous. Current consensus considers the Hell Creek specimens and those from the Canadian Dinosaur Park, which is similar age, to be different genera with Troodon preferred for the American genus and Stenonychosaurus for the Canadian ones.