Toward quantifying mesowear proxies: geometric morphometric mesowear (GMMW) method

International audienceMesowear was established as an efficient and quick tool for paleodiet reconstructions. It is a widely applied proxy that is used to infer an herbivore’s diet, providing insight into the dietary habits and environmental conditions of a population over years to lifetimes. This tooth wear technique macroscopically studies the morphology of tooth cusps, traditionally using qualitative up to semi-quantitative methodologies. But the classical approach is not free of bias: it is a (semi-)qualitative, observer-dependent approach, which also depends on the scale of observation. The lack of standardization limits comparisons between studies.Therefore, herein we propose a ”2D Geometric-Morphometric” mesowear method, that adds a fully quantitative dimension to the cusp shape scoring using geometrics morphometrics. This new method (GMMW) retains the time efficient quality of mesowear, while providing more accuracy, objectivity and being scale-independent. To test this novel technique, we used as a comparative baseline 111 sympatric extant ruminants belonging to 4 species (Cervus elaphus, Capreolus capreolus, Rupicapra rupicapra, Ovis ammon) with known diets. Additionally performing the GMMW on 82 fossils from the Lower Pleistocene Gerakarou locality (1 equid, 2 cervid, 4 bovid species; Mygdonian basin, Greece). We compared our results with a fully quantitative and a semi-quantitative method, applied on the same specimens. The extant species plot as mixed feeders, which was expected, but surprisingly the browsing roe deer had the most worn teeth. Browsers tend to have higher and sharper cusps than mixed feeders and grazers although thereare important overlaps. In Gerakarou, mixed feeders were found to have been dominant, indicating a mosaic environment. The equid had mesowear scores indicative of grazing. This new methodology seems to indeed be more shape-sensitive than former methods. Its standardization could solve theinability of data comparisons amongst studies. It still requires a wider experimentation basis in order to be completed