Palaeogeography, Palaeoclimatology, Palaeoecology 302 (2011) 213–229 Contents lists available at ScienceDirect Palaeogeography, Palaeoclimatology, Palaeoecology journal homepage: www.elsevier.com/locate/palaeo 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) Thalassa Matthews a,⁎, Amy Rector b, Zenobia Jacobs c, Andy I.R. Herries d, Curtis W. Marean b a Iziko South African Museum, 25 Queen Victoria Rd, Cape Town, 8000, South Africa b Institute of Human Origins, School of Human Evolution and Social Change, Arizona State University, Tempe, AZ 85287, United States c Centre for Archaeological Science, School of Earth and Environmental Sciences, University of Wollongong, NSW 2522, Australia d UNSW Archaeological Science Laboratory, integrative Palaeoecological and Anthropological Studies, School of Medical Sciences, University of New South Wales, 2052, NSW, Australia article info abstract Article history: PP9C is a coastal cave situated on the south coast, Pinnacle Point, Mossel Bay, and contains both Received 9 September 2010 archeological deposits, as well as fossil micromammal accumulations. Micromammals were analyzed from Received in revised form 14 January 2011 facies accumulated close to the transition from MIS (Marine Isotope Stage) 6 to MIS 5, between 130±9 and Accepted 19 January 2011 120±7 ka. The taphonomy of the assemblages indicates that the majority of micromammals became Available online 25 January 2011 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 Keywords: Pinnacle Point the available micromammal population and the fossil micromammal assemblages they produce are Micromammal comparable when tracing palaeoenvironmental change. The fossil assemblages suggest that the period Palaeoenvironment during which the micromammals accumulated was warm and wet, and that the vegetation within the Taphonomy hunting range of the owls accumulating the micromammal assemblages was relatively dense. There is, Diversity however, some evidence that at the time of deposition of the older assemblages, conditions were colder, Middle Stone Age 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,aswellasbymultivariateanalysis.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,wasacommon 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. © 2011 Elsevier B.V. All rights reserved. 1. Introduction rainwater, resulting in alkaline conditions in the sediments, and speleothem and tufa formation in the caves (Bar-Matthews et al., This paper presents a palaeoenvironmental analysis of micro- 2010). The result is that most of the sites at Pinnacle Point have mammal assemblages recovered from Cave 9C at Pinnacle Point, south excellent preservation of faunal material. PP9 currently presents coast, Western Cape Province, South Africa. PP9 is a large sea cave many excellent roosting spots, and many bird species live there today. complex formed in quartzite of the Table Mountain Sandstone Group PP9 consists of a number of smaller separate cavities named PP9A- (TMS) that outcrops along the southern Cape coast. The TMS in this E(Fig. 1). PP9A contains a deep, virtually sterile, dune in-fill and was area is capped by calcretes and calcareous sands that buffer the partially excavated in 2000 (Marean et al., 2004). No access to PP9D and E is available due to their location up near the roof of the PP9A cavity. PP9B was excavated in 2006 and is located to the left (south) of the PP9A cavern. It is a small, tube-like deposit in-filled with eroded ⁎ Corresponding author. Tel.: +27 21 4813877; fax: +27 21 4813983. raised beach deposits, MSA occupation horizons, and a capping of E-mail address: [email protected] (T. Matthews). sterile dune sand. PP9B was found to contain only 2 murid mandibles 0031-0182/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.palaeo.2011.01.014 214 T. Matthews et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 302 (2011) 213–229 mals includes the murids (mice and rats), bathyergids (mole rats), soricids (shrews), macroscelids (elephant shrews) and Chiroptera (bats). The Pinnacle Point micromammal assemblages are being studied in order to trace palaeoenvironmental change over a time period which includes global glacial and inter-glacial cycles. This is of particular interest as little information is available on glacial South African micromammal populations, and the Pinnacle Point cave sites present a unique opportunity to study the reaction of micromammal taxa to extensive climatic and environmental change over time in a particular area. Another MSA cave site at Pinnacle Point, PP13B, lies some 300 m to the south of PP9 and an analysis of the micromammals from horizons dating to specific non-continuous time periods during MIS 6and5(Jacobs, 2010; Marean et al., 2010) has been published (Matthews et al., 2009). There is some overlap in the younger time periods represented by PP13B and PP9 which provides an oppor- tunity to cross-check environmental information from the two cave sites. 2. Materials In November 2005, prior to the controlled excavation of PP9C, a surface collection was taken of a dense, surface micromammal accumulation situated towards the rear of the cave. This collection is referred to as Surface Scraping 2005, and abbreviated as ‘SS:2005’, in this paper. Several species found in this horizon suggest that much of the micromammal material is modern, although there may have been some mixing with the underlying fossil horizons. Five excavation squares were made in the PP9C sediments in October 2006. Individual ‘Stratigraphic Units’ (StratUnits) were initially identified during excavation based on color and consistency of the deposit. StratUnits were later grouped into larger ‘Stratigraphic Fig. 1. The Pinnacle Point caves PP9A, PP9B and PP9C. Aggregates’ (StratAggs, similar to “layers”), which reflected a homogeneous set of formation processes of roughly the same time period. The micromammals were grouped into StratAggs for the and an incisor (see Appendix B) and will not be reported on any purpose of analysis. further in this paper. Directly above PP9B is PP9C which was also The stratigraphy and ages of the various StratAggs are shown in excavated in 2006 and contains a complex series of geological Table 1, and the abbreviations used in this paper for these are shown deposits and MSA occupations that will be described in detail in in brackets following the full name of each aggregate. The two Rear another paper. The entrance to PP9C involves accessing a 10 m rock Tunnel Entrance (RTE) StratAggs, OYCS and BYDS, as well as the two face from PP9A and fixed ropes were used for excavation and Rear of Rear Tunnel (RTR) StratAggs, BYSS and BYCS, are contiguous sampling of this cave. PP9C consists of a ‘front cavity’ that leads to the with one another. The age of the PP9C deposits relative to those of mouth of the larger PP9A cavern and a ‘rear tunnel’ that is accessed by the Pinnacle Point sites PP13B and PP5-6 (which is being excavated crawling through a small hole in the rear of the front cavity. This currently), and some other south coast sites, are summarized in constriction is due to the infill of the mouth of the tunnel with Fig. 2. sediment, which contains dense micromammal accumulations. The Excavation of the RTE area was made in the entrance to the rear constriction leads through to a ~5 m long tunnel that contains tunnel of PP9C, slightly beyond the sediment infill constriction. Its speleothem, ancient eroded calcified deposits, and a dune containing deposits have been dated to 126±9 and 120±7 ka, using optically micromammal deposits, which range in depth from 1.1 m at the stimulated luminescence (OSL) dating of individual sand-sized grains entrance, to 0.3 m at the rear of the tunnel. of quartz (Jacobs and Roberts, 2007). Both ages are statistically The excavations at PP9 form part of research being carried out by the South African Coast Paleoclimate, Paleoenvironment, Paleoecol- ogy, Paleoanthropology project (SACP4) which is currently underway in the Mossel Bay area. The project involves the study of a number of archeological sites in the Pinnacle Point area dating to the Middle Table 1 Stratigraphy and dating of PP9C. Stone Age (MSA) which are being excavated in order to study the response of early human behavior to climate change. The majority of StratAggs OSL ages these sites contain micromammal accumulations (Matthews et al., PP9C-SS:2005 Undated 2009), the greater part of which appear to have been accumulated by Barn or Spotted eagle owls via the deposition, and then disaggregation PP9C-RTE Olive Yellow Cave Sand (OYCS) 120±7 ka over time, of regurgitated pellets. Small mammals have small home Brown Yellow Dune Sand (BYDS) 126±9 ka ranges, do not undertake seasonal migrations, and many have precise habitat requirements.