Tooth wear analyses track niche partitioning at Gerakarou, a 1.8 Ma old site from Greece

The climatic instability of the Early Pleistocene induced regional paleoenvironmental changes, which impacted faunal composition and dynamics. It coincides with the Homo dispersal out of Africa. The role played by the Eastern Balkans in this dispersal is at the heart of current scientific debates. The rich fossil assemblage of Gerakarou-1 (2–1.8 Ma; northern Greece) can provide important insight into the environmental conditions of that time and area. In this study, we provide insights into the dietary habits of the herbivore guild of Gerakarou-1 at both short and long-term scales based on two complementary dental proxies, mesowear and microwear textures applied on 70 specimens and we infer the local paleoecology and paleoenvironment. As diet varies between and among populations within the same species, we conduct a population-level study, including a reference dataset of 144 extant individuals belonging to six populations of ruminants with well-known ecology. As we aim to contribute to the collective effort of the community to improve the mesowear methodology, we propose and discuss here the benefits of an alternative, quantitative Geometric Morphometric approach. We show that the occlusal relief, as calculated in the classical mesowear approach, is a variable of little relevance and that the quantitative approach allows better discrimination between dietary categories. By proposing for the first time a multi-scale and multi-proxies study of the entire herbivore guild at Gerakarou-1, we nuance and clarify the paleoecology and niche-partitioning of the ungulates from this site and improve past paleoenvironmental interpretations.