Quantifying Relationships between Form and Function and the Geometry of the Wear Process in Bat Molars

摘要

Despite many important predictive features of bat dentition having been described in the literature, a number of these have not been given sufficient attention or measured on actual teeth. I aim to address this by establishing criteria for the choice of useful functional parameters of chiropteran dentition. These are: (1) they apply to tooth components rather than an entire tooth, where the three main tooth components are cusps, crests, and basins; and (2) they have a predictive element, so that changes in the parameter are readily interpretable in terms of changes in function, such as increased force or energy required for the component to function. Parameters that influence the function of cusps and crests, in forced crack propagation of tough foods are described in detail: tip and cusp sharpness, cusp occlusion relief, rake angle, crest relief, approach angle, food capture, edge sharpness, and fragment clearance. All the parameters were measured for the upper molars of the microchiropteran Chalinolobus gouldii. Many of the parameters did not change significantly with heavy wear, pointing to geometrical and design characteristics for the maintenance of shape with wear in the dilambdodont tooth form.