NEW INVESTIGATIONS INTO THE STABLE ISOTOPE ECOLOGY OF THE MAMMAL COMMUNITY FROM ELANDSFONTEIN, SOUTH AFRICA: IMPLICATIONS FOR C4 PLANT DISTRIBUTIONS AND HOMININ PALEOBIOLOGY IN THE CAPE FLORAL REGION DURING THE QUATERNARY

The contemporary winter rainfall zone (WRZ) along the west coast of southern Africa is dominated by low-height, shrubby, fire-adapted fynbos vegetation that utilizes the C₃ photosynthetic pathway. Although the modern distribution of this vegetation is clearly defined, we understand little about: 1) the spatial or temporal extent of fynbos taxa during the Quaternary, and 2) how this distribution affected the structure and behavior of the fossil mammalian community during this period. Here we present stable isotope data that bear on these questions from the site of Elandsfontein (EFT), a mid-Pleistocene (1.0 – 0.6 Ma) locality found in the WRZ with abundant, in situ fossils and artifacts found in direct association. We find that enamel δ¹³C values of large herbivores from the site (n=214) suggest minimal C₄ vegetation within a C₃ dominated system. However, δ¹³C values of teeth from the mole-rat Bathyergus suillus (n=81) at EFT are significantly higher than those of contemporaneous large herbivores and suggest a significant presence of plants utilizing the C₄ photosynthetic pathway. Additionally, we find that artifact density at EFT localities is positively correlated with δ¹³C values of B. suillus teeth, suggesting that more intense occupation may be associated with greater concentrations of C₄ vegetation. Lastly, we hypothesize that the consistent presence of water near springs at EFT may have facilitated conditions in which a significant proportion of C₄ vegetation could thrive in a place in which C₃ plants otherwise dominate.