Huge Dinosaur Tooth Found in Spain

It looks like dental paleontology may be a promising career. First, researchers in Japan found the fossilized teeth of an as-yet-unidentified tyrannosaur that measured about 17 feet long (this was big news because the fossil dates from the early Cretaceous, about 140 million years ago, before tyrannosaurs had attained plus sizes). Now, a team in Spain has found the nearly 10-centimeter-long tooth of an unidentified allosaur, which may have measured as long as 15 meters. The original title of the paper makes the discovery sound even more impressive: "Diente de Un Gran Dinosaurio Teropodo."

It's not hard to guess why teeth persist so well in the fossil record: the same characteristics that make them suited for crunching through bone (or tough, woody plants) also make them resistant to erosion. That's why so many dinosaurs have been "diagnosed" simply on the basis of their teeth, though it helps to have other bone fragments scattered nearby.