Paleoecological implications of the large mammals from a late glacial hyena den at Besaansklip (southwestern Cape, South Africa)

Southern Africa’s Cape Floristic Region (CFR) has long been a focus of research aiming to integrate relationships between Quaternary climate dynamics, terrestrial ecosystem change, and modern human origins. Pleistocene mammal assemblages play a key role in this research. However, a lack of securely dated sites, especially from the western coastal plains of the CFR, has posed a challenge for understanding faunal communities and their connection to Pleistocene climate dynamics. Here, we present the systematic paleontology and paleoecological analysis of the large mammals from Besaansklip, a well-dated late glacial hyena den (∼16,000 years ago) from the west coast of the CFR. We identified &gt;400 mammalian specimens from Besaansklip, which we use to infer past climate and terrestrial environments. Like other Pleistocene fossil assemblages in the region, Besaansklip has a high abundance and diversity of water-dependent grazers, many of which are extinct (e.g., <i>Equus capensis</i> and <i>Syncerus antiquus</i>) or extirpated (e.g., <i>Connochaetes gnou</i>). Stable carbon isotope analysis of ostrich eggshells from Besaansklip suggests a lack of C₄ grasses, implying a cool growing season and dominance of winter rainfall. These findings reinforce previous models suggesting that glacial phases of the Pleistocene were associated with increased moisture availability and productivity, and perhaps an expansion of grassy vegetation in the southwestern Cape.