(above)
Three views of a highly-eroded theropod tooth (unidentifed taxon) from the Judith River Formation (Campanian) of Montana. The tooth appears to be a shed. It has lost all of its enameloid coating and there are no serrations remaining on the tooth, although the carinae (ridges) that rooted the serrations are still present. All of the surfaces are smooth, and some of the dentine has also been removed, which has formed the tooth into an unnaturally narrow and sharpened shape. Eroded theropod teeth can be caused by natural exfoliation from weathering on the surface of the ground (freeze-thaw cycles), or they can be caused by exposure to stomach acids. Some theropods accidentally swallowed their own teeth while they were feeding. These teeth pass through the animal and are partially dissolved by the dinosaur's own stomach acids. It is unclear to me which of the two processes has eroded this tooth. Length of tooth = 29 mm.
(above)
A partially exfoliated Daspletosaurus tooth from the Judith River Formation. When found, the base of this shed tooth was buried in the rock and the tip of the tooth was exposed to the atmosphere. Length of tooth = 70 mm.
