Heritage Cases

Project Title: Life history of tortoises from archaeological or open-air sites of South Africa: implications for paleobiology, palaeoecology, and palaeobiogeography Name of the Applicant: Mohd Shafi Bhat, Post-Doctoral Fellow, Department of Biological Sciences, University of Cape Town, South Africa. <shafialig@gmail.com> Project Supervisor: Prof. Anusuya Chinsamy-Turan, Department of Biological Sciences, University of Cape Town, South Africa. <anusuya.chinsamy-turan@uct.ac.za> Summary Tortoises are crepuscular reptiles of the family Testudinidae (Batsch, 1788), which mostly comprises terrestrial forms. Testudinids are known from all sub-polar continents except Antarctica and Australia and occupy a wide range of habitats varying from rain forests in the Southeast Asia and South America, to the deserts of North America and Africa (Le et al., 2006). In South Africa, the bones of tortoises, almost all the terrestrial angulate Chersina angulata and very occasionally the water tortoise Pelomedusa sp., are extremely common in archaeological and paleontological sites from the near coastal regions of the southwestern Cape (Avery et al., 2004). Tortoises were probably used by humans at these sites as a source of meat as well as for making use of the shells (Parkington et al, 1992; Thompson and Henshilwood, 2014). These excavated assemblages range from the late Pliocene at Langebaanweg, through a number of highly significant Pleistocene rock shelters, including Diepkloof, to the immediately precolonial San and Khoi sites of the terminal Holocene (Thompson and Henshilwood, 2014). Because of this ubiquity, tortoises have the potential to reflect some of the key events in human evolution and to contribute to a better understanding of past diets and environments. Rationale Current archaeological analyses of tortoise remains focus on quantifying relative abundances through time, measurement of the distal humerus breadth as a proxy for animal size and very tentative estimates of age at death from surface morphologies of the carapace. It is clear that an ability to understand tortoise bone growth and then to apply what we can learn from modern comparative animals to the massive prehistoric collections available, would dramatically enhance our capacity to reconstruct ancient patterns of seasonal resource use and settlement of humans. Histological studies aimed at linking histological events to age and seasonality will allow us to describe with fair accuracy the nature and impacts of tortoise exploitation across different sites and through a lengthy time span. It is likely this will have implications for the evolution of human economic activity in the Cape, a key area for the emergence of modern people. Skeletochronology (e.g. Chinsamy-Turan 2005 and references therein) determined through histological analysis can be used to give a better age estimate, and season of death of the tortoises found at archaeological sites, but it can also demonstrate the response of individual tortoises to environmental influences and constraints within their lifetimes. Tortoise assemblages have been excavated from: Elandsfontein, Duinefontein, Hoedjiespunt, Diepkloof, Elands Bay Cave, Ysterfontein, Faraoskop, Klipfonteinrand and many Holocene sites in South Africa. These localities are scattered across the Fynbos landscape from the coastline to the margins of the Karoo and form a time space framework for understanding the changing ecology of human settlement. Aims and Objectives The aims of this study would be 1. Identification, description and taxonomical cataloguing of collected fossils resulting in assessing their phylogenetic perspectives. 2. Examination of their palaeobiology based on functional morphology and bone histology to deduce diet, growth strategies and lifestyle adaptations. Methodology The project will encompass detailed osteological description and comparative analysis with published material and those housed in different museums/institutions. An attempt will be made for global correlation based on faunal similarity. From each archaeological site, different sized femora, humeri and tibia will be selected (as a proxy for ontogenetic age) as limb bones are in abundance. Thin-sections of these bones will be prepared by using cutting and grinding technique as suggested by Chinsamy and Raath (1992). Before sectioning, these will be embedded in epoxy resin (Chinsamy and Raath, 1992; Chinsamy-Turan, 2005), and grinded and polished using carborundum (silicon carbide) powder or discs of various grit sizes (600–1200 μm). The bone surface will subsequently cleaned with 0.5 μm α-alumina (Al2O3) and the polished surface will be mounted on glass slides, and then thin sectioned to about 45 μm. The thin section obtained will again be ground down to a thickness of 30–35 μm. Final polishing of the specimen will be performed by 0.5 μm α-alumina liquid. The thin sections will examined under a polarizing petrographic microscope for detailed histological study and photographs will be taken by a mounted camera. Research outcome: From examination of the gross anatomy of the fossil tortoises, we will: -describe and taxonomically identify these tortoises -obtain some indication of size variation From the thin sections we will identify histological characteristics to:- -undertake a skeletochronological assessment of the bones -assess age structure of bones selected by early humans -determine the season of death of the tortoise -deduce information about early human foraging behavior The acquired information will be published in national and international literature through peer-reviewed journals and conferences.