Hadrosaur- Duck Billed Dinosaurs were quite common in the cretaceous and were plan eaters, grazers. They had several parallel stacks of 6 or more teeth in their jaws numbering some 300 teeth. They did not shed their teeth like other dinosaurs, rather the new teeth were pushed forward and the old teeth were worn down to nubs. These are broken teeth that fell out after the dinosaur died and they lossened.
This tooth measures .62 inches.
Hell Creek Formation