ANALYSIS OF DENTITION MORPHOLOGY OF ALLOSAURUS FRAGILIS (THERAPODA: AVETHEROPODA): IMPLICATIONS ON TAXONOMIC UTILIZATION OF ISOLATED SHED TEETH FROM LARGE BODIED THEROPODS

Dental morphology and its significance to theropod (Dinosauria: Saurischia) taxonomy is poorly understood among vertebrate paleontologists. Dentition morphology is closely linked to feeding; changes in dental morphology could provide a basis for adaptations linked to utilization of new feeding niches. Due to this relationship, it is possible that paleontologists could rely on preservation of dentition in the fossil record to aid in the understanding of theropod evolution. Isolated theropod teeth are fairly widespread in dinosaur-bearing deposits, unfortunately a significant majority of these isolated teeth are shed during hunting or scavenging and lack any root structures. To date there is little quantitative data to assign isolated crowns to distinctive theropod taxa. Detailed measurements will be taken form Allosaurus along with Tyrannosaurus, Carcharodontosaurus, Spinosaurus, Ceratosaurus, Torvosaurus, and Acrocanthosaurus. Variables to be measured will include crown base length, crown base width, crown height, and apical length along with a series of morphologically relevant ratios and angles, including the crown base ratio, crown height ratio and the crown angle. Counts will be taken to determine the average number of denticles on the mesial and distal carinae of each tooth. The measurements and counts taken will be complied into a database of morphological standards that can be used to identify shed teeth found in rocks of the Late Jurassic age Morrison Formation. Owing to enamel’s property as the hardest biological substance known, isolated teeth are commonly found among dinosaurian assemblages. In several instances shed teeth have been used to extend pre-existing paleobiographical ranges. A study based solely on isolated dentition must be viewed critically, such identifications are based on an assumption of phylogenic affinity and results are approximations of those gained from using in-situ dentition of know taxonomy. It is there for the goal of this project to discuss in detail the dentition of a single theropod, Allosaurus fragilis and create a database of dentition values from A. fragilis and other large theropods. The emphasis will be placed on in-situ dentition, and the use of morphologic standards in the taxonomic identification of isolated teeth.