Ecological variability of Hippopotamus antiquus from the late Early–Middle Pleistocene of Megalopolis Basin (Greece): Evidence for dynamic habitats in a glacial microrefugium

This study investigates the ecology of the extinct European Hippopotamus from the late Early–Middle Pleistocene ( c . 900–400 ka) sequence of the Megalopolis Basin, a glacial microrefugium for temperate taxa in southern Greece. Using stable carbon (δ ¹³ C) and oxygen (δ ¹⁸ O) isotope analyses and microwear analyses of Hippopotamus dental elements, we reconstruct dietary variability, past habitat conditions and hydrological or climatic changes at intra‐annual, multi‐annual and millennial scales. The results indicate the dominance of C ₃ woodland/mesic grassland environments throughout the examined period and jointly suggest a broader aridification trend from MIS 16 to MIS 12. The studied individuals followed a browsing to mixed‐feeding diet and exhibited seasonally variable dietary habits. They also record potential short‐term climatic or hydrological shifts, which likely further impacted habitat or resource availability in the area. The incidence of enamel hypoplasia in early Middle Pleistocene specimens, which is tentatively correlated to cooler conditions, shows that the taxon survived in the region even during stressful, less optimal periods. These findings provide a crucial framework to better understand the ecological niche of the species, as well as the impact of dynamic ecosystems on adaptations of large mammals, including hominins, in the European Middle Pleistocene.