Recently, ambient occlusion, quantified through portion de ciel visible (PCV) was introduced
as a method for quantifying dental morphological wear resistance and reconstructing diet in
mammals. Despite being used to reconstruct diet and investigate the relationship between
dental form and function, no rigorous analysis has investigated the correlation between PCV
and diet. Using a sample of platyrrhine and prosimians M2s, we show average PCV was significantly different between most dietary groups. In prosimian, insectivores had the lowest
PCV, followed by folivores, omnivores, frugivores, and finally hard-object feeders. In platyrrhines, omnivores had the lowest average PCV, followed by folivores, frugivores, and finally
hard-object feeders. PCV was correlated to two topographic variables (Dirichlet normal
energy, DNE, and relief index, RFI) but uncorrelated to three others (orientation patch count
rotated, OPCR, tooth surface area, and tooth size). The OPCR values here differed greatly
from previously published values using the same sample, showing how differences in data
acquisition (i.e., using 2.5D vs. 3D surfaces) can lead to drastic differences in results. Compared to other popular topographic variables, PCV performed as well or better at predicting
diet in these groups, and when combined with a metric for size, the percent of successful
dietary classifications reached 90%. Further, using an ontogenetic series of hominin (Paranthropus robustus) M2s, we show that PCV correlates well with probability of wear, with
PCV values being higher on the portions of the occlusal surface that experience more wear
(e.g., cusps and crest tips, wear facets) than the portions of the tooth that experience less.
This relationship is strongest once wear facets have begun to form on the occlusal surface.
These results highlight the usefulness of PCV in quantifying morphological wear resistance
and predicting diet in mammals.