Forest Floor Leaf Cover as a Barrier for Dust Accumulation in Tai National Park: Implications for Primate Dental Wear Studies

Abstract

Mastication causes distinct use wear scars on teeth that can aid in dietary reconstructions of fossils. However, the role played by exogenous grit in dental wear complicates the association between wear and diet. Dental wear analyses often assume that foods closer to the soil contain more exogenous grit than those in the forest canopy. Yet, a layer of leaf litter covering many forest floors may trap grit from the soil, keeping it from settling on surrounding vegetation or becoming part of atmospheric dust. Cercocebus atys is frequently referenced in dental wear studies because of its dependence on hard Sacoglottis gabonensis seeds collected from the forest floor. Here we examine quantities of dust deposition at different forest levels and assess its potential role in wear patterns observed in C. atys. We collected grit from S. gabonensis seeds (N = 64) found under the leaf litter and compared them to grit samples taken from the surface of leaves at different forest strata (N = 450) in Ivory Coast’s Tai National Park. Seeds underneath the leaf litter were coated with significantly more grit than leaves above the leaf material and we conclude that leaf litter is a significant barrier to grit particles originating from the soil. Given that evidence points to a significant difference in grit amount between foodstuffs on the ground and foods near the ground, the findings lead to a prediction of differences in dental wear patterns between purely arboreal foragers and those incorporating terrestrial food sources.