FIRST REPORT OF TOOTH WEAR IN ALLOSAURUS FRAGILIS AND POTENTIAL AVENUES FOR PALEOECOLOGICAL STUDY

Inferring feeding habits in more detail than just carnivore versus herbivore is important for reconstructing the detailed paleoecology of extinct organisms. Questions regarding the food quality available to or exploited by certain taxa can be particularly difficult to approach. The extensive collection of Allosaurus fragilis material recovered from the Cleveland-Lloyd Dinosaur Quarry (CLDQ) includes several dentaries, premaxillae, and maxillae with intact teeth as well as several isolated teeth. These teeth exhibit a variety of tooth wear features including carinal wear, oval-shaped facets, abrupt fractures and enamel spalling.

There is some circumstantial evidence to suggest that Allosaurus engaged in osteophagy, at least occasionally. The presence of processed bone in a coprolite from the Upper Jurassic of the Morrison Formation may indicate that Allosaurus ingested bone. The teeth of Allosaurus are relatively robust and statistical analysis shows that they are within the range of bone masticating theropods, namely Gorgosaurus, with respect to crown compression ratios. Conversely, tooth-marked bones from the Morrison Formation support the hypothesis that predatory dinosaurs did not regularly chew the bones of their prey. Also, biomechanical modeling suggests that Allosaurus processed carcasses differently than large tyrannosaurids which have been considered bone crushers. The amount and type or wear observed in the CLDQ material is similar to that found in other robust-toothed theropods (e.g., tyrannosaurids) and supports the hypothesis that Allosaurus regularly engaged in durophageous activity.

Analysis of tooth wear surfaces is potentially important to understanding the paleoecological roles of extinct animals. Dental microwear texture analysis (DMTA) has recently been shown to be a useful tool in predicting the feeding habits of extant carnivoran mammals. DMTA quantifies microscopic, three-dimensional tooth textures and provides a valid proxy for the degree of durophagy in which an individual engages. Dental microwear has been found in several dinosaurian taxa, both carnivorous and herbivorous, but has yet to be documented for Allosaurus. We plan to perform a DMTA on the CLDQ material which will elucidate the extent to which Allosaurus may have engaged in osteophagy.