THE VARYING DENTITION OF ALLOSAURUS: A FUNCTIONAL MORPHOLOGY EXPERIMENT

Functional morphology experiments are an important method for exploring the ecology of an animal, including reconstructing predator-prey interactions in extinct taxa. Allosaurus possesses morphologically distinct teeth in different regions of the mouth, which suggests that these regions may have served different functional roles. The purpose of this study was to assess the function of the different morphotypes of Allosaurus teeth by determining which morphotype recorded the greatest puncture depth into a compliant medium given a constant amount of applied force. The dentition of Allosaurus was divided into three categories based on morphology and location within the mouth: D-shaped in cross section in the rostral portion of the premaxilla, laterally-compressed in the maxilla, and transition teeth which are found between the premaxilla and maxilla and are typically square in cross section with off set serrations. Teeth specialized for puncturing are expected to result in the greatest puncture depth given a constant amount of applied force. The transition tooth morphotype are hypothesized to fill this functional role based on a typically low apical angle. Isolated Allosaurus teeth collected from the Something Interesting (S.I.) Quarry, Thermopolis, Wyoming were laser scanned and 3D printed. These teeth were placed in a testing apparatus and the puncture depth of each tooth in a ductile medium in response to a constant amount of applied force was measured. It was shown that that teeth belonging to the D morphotype reached the greatest puncture depth in the medium, which suggests that this morphotype would be most efficient for puncturing. This can be attributed to a relatively low apical angle, which allows for a greater percentage of a tooth's mass to be concentrated over a single point. The results of this research demonstrate that the D morphotype is specialized for the purpose of puncturing, which suggests that Allosaurus may have used the rostral portion of its mouth for this action. Since the transition morphotype has a typically lower apical angle than the D morphotype, further experimentation will be completed in order to tell if the results were subject to sample bias.