The vast majority of the Western Science Center's fossil collection comes from Pleistocene deposits in Riverside County, so most of our specimens are less than 200,000 years old. Being so geologically young, birds are almost the only dinosaurs in our collection, as birds were the only dinosaurs to survive the mass extinction at the end of the Cretaceous Period 65 million years ago. We do, however, have a handful of much older, non-avian dinosaurs at the museum.On the left above is a partial single tooth from Tyrannosaurus rex from the Late Cretaceous Hell Creek Formation in Montana, which was collected by Harley Garbani and donated to the museum by Harley and his wife Mary. The tooth was apparently found isolated, which is not uncommon with dinosaurs as they shed teeth throughout their lives. As is typical of Tyrannosaurus and other theropods, the tooth has serrated cutting edges, one of which is visible near the left edge of the tooth. There is noticeable apical wear at the tip of the tooth, which is somewhat rounded off.This tooth was one of the first subjects for our molding and casting program. At the center of the photo is an unpainted resin cast of the tooth, and on the right is a painted cast. The serrated cutting edge is actually more visible in the cast than in the original specimen.The original specimen is on display at the Western Science Center as part of the "Harley Garbani: Dinosaur Hunter" exhibit. Replicas of the tooth will be available in the museum store early next year.