Dental microwear of cave bear (Ursus spelaeus) reveals locally adapted foraging strategies in South-Eastern Europe during late MIS 3

Cave bears (Ursus spelaeus sensu lato) represent a remarkable example of Late Pleistocene megafauna, whose ecology and extinction dynamics remain a subject of intense debate. This study investigates the short-term dietary ecology of Late Pleistocene (mainly late MIS 3) South-Eastern European cave and brown bear populations (n = 316) using dental microwear analysis (DMA) on specimens from Romanian Carpathians (n = 160), Moldavian Plateau (n = 58), Western Balkans and Western Rhodopes (n = 65) and Central Balkans (n = 32). By analysing and quantifying microwear features, this research captures the final days-to-weeks dietary behaviour prior to death, offering a high-resolution perspective complementary to isotopic and morphological analyses. Complementing the prevailing view of cave bears as highly specialized herbivores, our results suggest a seasonal ecology more comparable to that of extant northern hemisphere ursids, characterized by landscape-based dietary opportunism. This inferred dietary flexibility is further supported by local-scale niche partitioning, and possible regional niche overlap with contemporaneous southern refugia dwellers U. arctos populations. Evidence of dietary flexibility, closely tied to their immediate environment, supported by new radiocarbon dates (n = 16), with the youngest at 35 ka cal BP (Butești), calls for a reassessment of cave bear extinction dynamics. Ecological specialisation, particularly during resource-scarce seasons and in refugia areas, combined with pre-hibernation ecological pressures, likely contributed to a gradual, multifactorial extinction process. This localized dietary endemism may have limited the species' ability to adapt when climatic conditions deteriorated during MIS 3.