Albertosaurus had a matching set of upper and lower teeth-their functions were consistent from front-to-back along the jaw-but in Tyrannosaurus the patterns of the upper and lower teeth differed. There was one notable way in which Albertosaurus and Tyrannosaurus differed, though. The small and stout front teeth were likely used for pulling large pieces of meat from carcasses, the much larger teeth in the middle of the jaw were adapted to coping with the stresses of struggling prey, and the teeth at the rear of the jaw were positioned to deliver heavy, crushing forces in an arrangement Reichel likened to a clamp. (The differences between the teeth can perhaps best be seen in the skull of the juvenile Tyrannosaurus " Jane".) What Reichel wanted to know was how these various teeth functioned, and so she created computerized, 3-D models of Albertosaurus and Tyrannosaurus teeth to test how they would have held up to the stresses and strains created by biting.Īs might be expected for large predators, the teeth of both tyrant dinosaurs were suited to different tasks. The teeth at the front of the jaw are small and closely packed those in the middle of the jaw are exceptionally long and curved and those at the back of the jaw are smaller and only slightly recurved. What this meant for how the tyrant dinosaurs ate was addressed in a Canadian Journal of Earth Sciences paper by Miriam Reichel last year.Īlthough the teeth of Albertosaurus and Tyrannosaurus may seem to be all the same, these dinosaurs actually had three different tooth classes. Pakasuchus, an extinct cousin of modern crocodiles found in the 105-million-year-old rock of Tanzania, had three different types of teeth in its jaws, and even the mighty Tyrannosaurus and Albertosaurus possessed differentiated teeth. Among reptiles, on the other hand, multiple species have been found with a variety of tooth shapes in their jaws. Dolphins, for example, have jaws full of nearly identical, conical teeth. Not all mammals have differentiated sets of teeth. The dental differences were presented as one of the ways in which mammals were superior to reptiles, but like a number of other things I was taught in grade school, this wasn't quite right. Mammals had a full, enamel-covered toolkit in their mouths-incisors, canines, premolars, and molars suited to different tasks-while reptiles had only one kind of tooth. When I was in elementary school, I was told that mammals and reptiles could easily be told apart by their teeth.
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