Large herbivore δ¹⁸O as a proxy for aridity in the South African winter and year-round rainfall zone

Abstract This study explores patterning in δ 18 O values of tooth enamel in contemporary African herbivores from mainly C 3 -dominated ecosystems. Evapotranspiration causes plants to lose H 2 16 O to a greater extent than H 2 18 O, leaving leaves enriched in 18 O. In eastern Africa, ES species (evaporation-sensitive species: those obtaining water from food) tend to have more positive δ 18 O enamel values than EI species (evaporation-insensitive species: those heavily dependent on drinking water); the magnitude of the difference increases with increasing aridity. We find the same pattern applies in the winter and year-round rainfall region of southern Africa, allowing us to use δ 18 O enamel in fossil animals to examine paleo-aridity. We apply this approach to infer aridity at Quaternary fossil assemblages from present-day winter and year-round rainfall zones, including Elandsfontein (ca. 1–0.6 Ma), Hoedjiespunt (ca. 300–130 ka), and Nelson Bay Cave (23.5–3 ka). This analysis suggests that (1) at various times during the Pleistocene, Elandsfontein and Hoedjiespunt environments were wetter than last glacial maximum (LGM) to Holocene environments at Nelson Bay Cave (year-round rainfall zone); and (2) considered alongside other evidence from the year-round rainfall zone, wetter conditions across the Pleistocene–Holocene transition at Nelson Bay Cave suggests that climate changes at near-coastal sites may be out of phase with the adjacent interior.