PLAIN LANGUAGE SUMMARY:

Tooth shape reflects diet in mammals because foods with different material properties require differently shaped teeth to break them down. For example, sharp blade-like teeth would better slice raw meat than would blunt, hammer-like teeth suited to crushing hard, brittle foods. Paleontologists have used relationships between tooth shape and diet in living mammals to infer feeding adaptations from the shapes of fossil mammal teeth. Most such studies have relied on unworn (rather than worn) teeth because it is easier to measure functional aspects of their shape and to compare measurements among species. Still, tooth shape changes with wear, and most fossil teeth found are, in fact, worn. For an example of the investigation of tooth wear by more conventional means, and its use as a basis for inferring the diet of some Paleocene ungulates, see E.W. Dewar, 1997, Journal of Vertebrate Paleontology, vol.17A.

The study described here offers a new way to characterize and compare dental anatomy among variably worn teeth. This approach uses geographic information systems (GIS) to examine teeth as topographic landscapes, modeling their cusps and grooves as mountains and valleys. Slope, aspect, surface area, volume, and other measures can be measured and compared among specimens. This is demonstrated with a series of variably worn teeth from one species, the gorilla. Results show that some attributes, such as surface area and slope, decrease with more and more wear. Other attributes, such as angularity of the surface do not seem to change with tooth wear, suggesting the maintenance of some aspects of chewing efficiency. We conclude that dental topographic analysis will allow us to measure the ways that teeth change shape as they wear, permitting the evaluation of changes in chewing efficiency, and perhaps even the reconstruction of the diets of fossil mammals using worn teeth.

Glossary:

Dental topographic analysis: a method for modeling the shapes of the biting surfaces of teeth as topographic surfaces for analysis using Geographic information systems technology.

Digitial elevation model: a set x,y,z data where x and y values represent points on a two-dimensional surface and z values indicate elevation.

Functional morphology: the study or relationships between the shape of a biological structure and how it functions.

Geographic information system (GIS) - a system for assembling, storing, manipulating, analyzing, and displaying geographically referenced information