A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg 1994. / This thesis presents an :investigation into the functional morphology and form of the skeletal elements of" the shoulder girdle of extant h0111inoids and extinct hO)ll.inids\~hich inhabited the Afr:i.c~n continent during the Late pliocene and Elarly \Ii Ii \Ii, ill Partic'l.l.lcu: emphasis is placed o\~\the \' i\. form of the scapula, clavicle and humerus. \Ii variation in the bony, arthrological and 41.yoloQif\;Lcal I" anatomy' Of this region in extant hominoids is I Pleistocene. examined. In light of biomechaniq~l models II reSUlting from this work, the bony,;anatomy of u hominid shoulder girdle elements examined and i. .1 r;:I~t>. ssil .1,1 . " biomechanical interpretations are made. The fossil shoulder girdle elements exan\ine~ in this study are grouped into four species samples. The first sample (Australopithecus a.:friCaIlUS) comprises Pliocene ,fossils from sterkfontein, South Africa. 'rhe second sampJ.e (A. afarelJ.si.s) i.s comprised of fossilo front Hadar, Ethiopia. The third (Homo habilis) and, fourth (ii. boisei) samples comprise fossils from C'lduvai GorgeI Ta:nzania, Koobi For~ll, Ke!nya and t.ne omo Valley ~ Ethiopia. When the t!;ossil homi.ndd. remains are scrt.ed into specf.ea, jl~heI:;houlder g;l.rdle elements InelYd:>e used to const.zuct; and contrast specd.es specijSiq '1· . ) bitOmechar1,ic::aml odelS of th~ shoulder. Th~~se models e:>fltP10re differernoes in form amon~,r.;tj;ossil hominid. species that may'be reJ,ated to dii.:;eetenc;:.es in behaviour. The models may also be appU.ed to the :~......,..~ interpretation of systemat.ic relationShips amongst early hominids. In o:(.~ierto construct models of early homi:p,ids it is first necessary to establish the,movement, myology and oste0logy of the extant hominoid shoulder. Chapters 4,5 and 6 sUl'l.1Il1ar~n,$eew data and available in,formation concel:"ning shoulder girdle mo.Jementand form. Chapter 7 presents detailed C';escriptiQns Of the fossil hominid ma.terial (u:::::19) available for study. 'rhis descriptive information, in conibination with all of the information derived from Chapters 4 through 6, is then used to inte1.pret, compaxe and contrast the fu.nctional morphology Of the shoulder girdle elements of each species of early hotninid. pa:q:ticuJ.ar emphasis is placed .on those features that cart be. directly related to specific :functiOl'l~ Model.s ,,.l the functional morphology of each of t1Je four species are then created. comparisons are made between indJ.vidual Shoulder girdle elements 'cg,fthe different homj.nid spacd.es as well as between the interpreted total morphology of each species' shoulder girdle. The study concludes that the functional m~>l':phologyof the shoulder girdle Qf A. afriaanus is unique ~unorJ.gstknown hominoic1~mode'l.s in that it poasesaes shoul<;ier girdle mo;t,'ph.oo.)gy adapted to bobh suspen ory behaviour and bipE~d;;d~i.srn. TIte suspensory adaptations are :Lndi9ated by the overall ape ..like morphology of the humeri, claviculae and heCid.of the scapulae, whilst bipedalism is mainly (J G indicated. by a broad, human-like inf.Ell:'ior'an9,'].eof " = the scapula. Several' RpparentlY prim.itive featu:r:es" are present in,..the A. africanus Ejcapl,1la,incl~dirtg a 0i,? ..... . _ .. '. \ shortened scapular 'n~ck, that ind:l.Cate'-\poss~ple ancestry f.roma quadru:pedal form. ~p.e functi<:>tJ.al. morphology of the A. afarens.ts shoulder is founa .to be more diffi.cult to interpret d'.le to poor f(i:; ,pre.~ervationt but the hypothesised znodel'~does not diffe):: substantially from th~t constructed for A. _c,~) . ..' .', 1) (; a£ricanus. The few robust aURtra.lopithecine,.,(A. boi.se:1) sho~~der girdle elements appear to possess ~,.. similar morpJ;lologi.esto A. a.:falyrnsis and )1- africanus. There ara .no'l:.SUfi:'lc:tently well preServedoH. habili.s shoulder girdle elements preserved to 'makemeffilningfulinterpreta.tions about the functional morphology of this, specie~:' .' n the lack of comparable elements amongst the two (I 1arger samples (...21.. a:faJ;'ensi.s and ,fl. arr:J;canus) I .it '..':::/ is not knownwhether the features found to be apparently unique to either species are useful as n taxonomic indicators.

Swartkrans Cave, famous for abundant hominin fossils of P. robustus and the site where the first evidence of the co-existence of two hominin species was recovered, has yielded a wealth of information on early hominin behaviour. In 2005 a new program of research and excavation began at the site, and its results form the central part of this thesis. This study has focused on the early Pleistocene Member 1 deposits which include an Earlier Stone Age industry and the late Pleistocene Member 4 Middle Stone Age deposits. The thesis has four areas of focus. First the new work has resulted in clarification and new interpretations for the formation of the hominin rich Hanging Remnant deposit of Member 1, which lacks stone tools. This extensive calcified conglomerate which spans most of the north wall of the cave is now seen as a non-homogenous unit that represents material entering from at least four avens. However, this study also established that the newly exposed central portion of the Hanging Remnant and the hominin fossil-rich northwest corner infill worked by Robert Broom in the 1940s derived from the same depositional episode. Secondly, the new excavations in the Lower Bank of Member 1 have resulted in an enlargement of the previously ambiguous Earlier Stone Age assemblage. Analysis of this new assemblage, in conjunction with recently released dating results, has now confirmed that the artefacts belong to the Oldowan Industrial Complex. Thirdly, new excavations in the Member 4 deposit have resulted in the recovery of over 3,200 Middle Stone Age (MSA) stone tools and a clearer understanding of their context. The stone tool-bearing deposits of Member 4 are now understood to derive from a surface colluvium, rather than a cave infill. This MSA assemblage consists of a high number of retouched pieces that are dominated by steep-sided scrapers and denticulated scrapers with a near-absence of points. The technology of a variety of core types suggests a superior understanding of raw material flaking qualities by the tool makers. The limited types of formal tools suggest that the site was used for one or more specific activities, rather than for a range of activities by the tool makers. Fourthly, excavation of the deposits underlying the Member 4 colluvium has resulted in the discovery of two previously unknown hominin-bearing deposits. It is now established that what was originally called Member 4 is composed of three distinct deposits. The lowest of these is an east extension of the Member 1 Lower Bank (LB East Extension), which has yielded P. robustus fossils. This is overlain by a large talus cone (TCD), which also has yielded P. robustus fossils. The latter is capped by flowstone dated to ~110,000 years, followed by the MSA-tool bearing colluvium.

M.Sc. (Geology) / The Cradle of Humankind is a 47 000 hectare demarcated area with over three dozen fossil-bearing cave sites well known for the preservation of fossil evidence of early hominin taxa such as Australopithecus Africanus, Australopithecus Sediba, Paranthropus Robustus and Early Homo. As a result, a database of precise and accurate chronological data for fossil-bearing cave deposits of the Cradle of Humankind (similar to that for East African fossil sites) is very important, but developing one has proven extremely challenging. The main challenge is that the fossil-bearing deposits at the cradle are mainly complex breccias with a chaotic, localized stratigraphy and no association to any volcanic ash beds, unlike the East African deposits which are lacustrine and fluviatile deposits interbedded with volcanic ash layers. However, substantial success has been obtained recently through the combination of U-Pb dating of CaCO₃ speleothems and palaeomagnetic dating (magnetostratigraphy) after many attempts and unconvincing results from techniques such as biostratigraphic correlations, electron spin resonance on teeth and cosmogenic burial dating of the sediments. The problem with U-Pb dating of CaCO₃ speleothems is that this requires samples that are extremely clean (i.e. detrital-free) and have an appreciable U content (close to 1 ppm), and such material is at many sites not available...