Environmental implications of micromammals accumulated close to the MIS 6 to MIS 5 transition at Pinnacle Point Cave 9 (Mossel Bay, Western Cape Province, South Africa)

PP9C is a coastal cave situated on the south coast, Pinnacle Point, Mossel Bay, and contains both archeological deposits, as well as fossil micromammal accumulations. Micromammals were analyzed from facies accumulated close to the transition from MIS (Marine Isotope Stage) 6 to MIS 5, between 130 ± 9 and 120 ± 7. ka. The taphonomy of the assemblages indicates that the majority of micromammals became associated with the site when they were deposited in Spotted eagle owl or Barn owl pellets. Modern comparative studies suggest that these two predator species select a very similar suit of prey species from the available micromammal population and the fossil micromammal assemblages they produce are comparable when tracing palaeoenvironmental change. The fossil assemblages suggest that the period during which the micromammals accumulated was warm and wet, and that the vegetation within the hunting range of the owls accumulating the micromammal assemblages was relatively dense. There is, however, some evidence that at the time of deposition of the older assemblages, conditions were colder, relatively grassier, and may reflect a rather more open environment. This difference may indicate the change from glacial MIS 6 to inter-glacial MIS 5e climatic conditions. These conclusions are supported both by the habitats and habits of the micromammal faunas, as well as by multivariate analysis. E. edwardii and A. namaquensis appear only in the earliest fossil assemblages at PP9C, and their general scarcity suggests that the rocky and open habitat preferred by these two species was never available on a wide scale at Pinnacle Point. The Pinnacle Point fossil sites indicate that the soricid, C. flavescens, was a common component of the local micromammal fauna and occurred in the area during some of MIS 6, and into MIS 5, suggesting that this species was able to adapt to glacial/interglacial cycles, and may utilize drier habitats than commonly reported in the literature. The fossil evidence indicates that C. cyanea, S. infinitesimus and Saccostomys campestris are relative latecomers to the Mossel Bay region. S. campestris appears only in PP9C in surface sediments, and confirms previous suggestions that the arrival of this species to the southern Cape occurred sometime within the Holocene.