Lf. Zuccotti et al., TECHNICAL NOTE - MODELING PRIMATE OCCLUSAL TOPOGRAPHY USING GEOGRAPHIC INFORMATION-SYSTEMS TECHNOLOGY, American journal of physical anthropology, 107(1), 1998, pp. 137-142
Most functional analyses of primate tooth form have been limited to li
near or area measurements. Such studies have offered but a limited gli
mpse at differences in occlusal relief among taxa. Such differences in
dental topography may relate to tooth function and, so, have consider
able implications for the inference of diet from fossil teeth. In this
article, we describe a technique to model and compare primate molars
in three dimensions using Geographic Resources Analysis Support System
(GRASS) software. We examine unworn lower second molars of three exta
nt hominoids with known differences in diet (Gorilla gorilla, Pan trog
lodytes, and Pongo pygmaeus), and two fossil forms, (Afropithecus turk
anesis and Dryopithecus laietanus). First, we obtained approximately 4
00 landmarks on the occlusal surfaces of each tooth using an electroma
gnetic digitizer. Raster ''terrain models'' of occlusal surfaces were
then created by interpolation of the coordinate data. We used GRASS te
rrain analysis automated techniques to quantify the volumes and slopes
of individual cusps. We also used the GRASS watershed technique to id
entify the volume of liquid that would accumulate in each tooth's basi
n (a measure of basin area), and the directions and intensity of drain
age over the occlusal surface. In sum, GRASS shows considerable potent
ial for the characterization and comparison of tooth surfaces. Further
more, techniques described here are not limited to the study of teeth,
but may be broadly applicable to studies of skulls, joints, and other
biological structures. (C) 1998 Wiley-Liss, Inc.