PRACTICAL APPLICATION OF THE MESOWEAR METHOD ON UNASSOCIATED TEETH OF NEOGENE EQUIDAE

The mesowear method of Solounias and coworkers was proposed as a relatively quick and efficient method of paleodiet analysis. It originally focused on cusp shape and occlusal relief of the upper second molar (M2). This method has been extended, using hipparionine and extant equids, to include the combination of P4, M1, M2, and M3 positions, which is the most consistent combination with the original M2 model. Both the original and current model, however, rely on positive identification of tooth position. Because fossil teeth are often found unassociated, it can be difficult to attain such identification. It is not always possible to distinguish between a P4 and M1 or between a M1 and M2. In the interest of assessing the practical applications of the mesowear method, this study applies the mesowear method to the P3-M2 tooth types and simulates random sampling. Additionally, this study utilizes a broader taxonomic range, consisting of equids from multiple tribes displaying morphological and temporal diversity. The specimens vary in tooth morphology from mesodont to hypsodont and span an age range of 18 Ma.

Statistical goodness of fit (χ²) tests were conducted on cusp shape and occlusal relief of the M1, P3, and P4 of six fossil equids to their respective observed M2 values. The same tests were conducted on sets of 20 randomly chosen teeth from each taxon in order to simulate realistic sampling of unidentified isolated teeth. Additionally, the paleodiet classification of each equid was determined, using each tooth type separately in cluster analyses, as well as combinations of different tooth types. For each taxon, the M1 and P4 fit well with the M2 observations, and yielded the same paleodiet classification. The P3 was inconsistent with both the goodness of fit tests and paleodiet classification (a discrepancy in one of the six taxa). This study has determined that, while positive identification of teeth is obviously preferred, a general paleodiet classification can be obtained from any combination of unidentified P4/M1/M2, requiring only the exclusion of more easily identifiable P3 teeth.