Organic matter and biomarker data from Diepkloof Rock Shelter, South Africa

This constitutes the first leaf-wax isotopic data in a terrestrial context of this antiquity in South Africa. Py-GC/MS shows a dichotomy between stratigraphic units (SUs) of high organic matter content, producing a range of pyrolysis products, including homologous series of long chain n-alkene/n-alkane doublets and alkyl-nitriles, and SUs of low organic matter content, dominated by aromatic, heterocyclic N and polycyclic aromatic hydrocarbon (PAH) pyrolysis products; typical molecular burning products.

Several SUs of the Intermediate Howiesons Poort interval exhibit the latter composition, consistent with micromorphological evidence. d13Cwax remains stable throughout the MSA, but leaf-wax n-alkane chain length and dDwax increase during the Late Howiesons Poort interval. Comparison with such patterns in modern plants in the region suggests this represents a shift towards the input of more arid-adapted vegetation into the shelter, driven either by aridification at the site locale or a change in selection practices.

Our results suggest that these techniques have further potential in southern Africa and globally at sites where organic matter preservation is high.