A Comparison of Tooth Microwear Between an Extinct Marsupial Predator, the Tasmanian Tiger Thylacinus-Cynocephalus (Thylacinidae) and an Extant Scavenger, the Tasmanian Devil Sarcophilus-Harrisii (Dasyuridae, Marsupialia)

Abstract

Tooth microwear patterns in the predator Thylacinus cynocephalus and the scavenger Sarcophilus harrisii were examined as potentical indicators of dietary differences and occlusal mechanics. Homologous proximal facets on the metacrista of the maxillary right 3rd molar of each species were examined as gold coated replicas under the SEM. The density, dimensions and relative abundances of microwear features were recorded. Significant intrafacet microwear variation exists relative to the direction of the occlusal stroke in Thylacinus. Striation and pit frequency are inversely correlated down the facet, with striations being more frequent at the leading edge; pits are larger and more frequent at the trailing edge. This pattern supports proposed models of the carnassial chewing stroke, where it is predicted that the shearing component, that produces striations, is greater at the leading edge of the facet, while the compression component of the occlusal stroke, which results in relatively more pits, is greater at the trailing edge of the facet. Significant intraspecific and interspecific variation is found in microwear feature dimensions, and densities. Pit diameters and densities are significantly greater in Thylacinus, although only approximately 11% of the total variance in these features was attributable to species differences. The remaining variance was distributed equally between individuals of the same species, and the leading and trailing regions of the facet. The high degree of intraspecific variability indicates that in carnivorous species at least, a sufficient number of individuals must be examined before accurate dietary interpretations and comparisons with other species can be made.