Le taxon du Pléistocène inférieur Paranthropus robustus, dont l'holotype est le spécimen TM 1517, a été défini en 1938 par le paléontologue R. Broom suite à la découverte d'éléments crâniens et postcrâniens sur le site de Kromdraai, Gauteng, en Afrique du Sud. Depuis, d'autres sites sud-africains ont contribué à l'extension de son hypodigme et fourni la preuve de sa contemporanéité à l'échelle macro-régionale avec des représentants des taxons Australopithecus et Homo. L'identification des hominines étant principalement basée sur l'analyse de la variation morphologique des éléments cranio-dentaires, un enjeu majeur dans l'étude des assemblages fossiles des sites sud-africains concerne donc l'identification et l'attribution taxinomique de restes isolés et/ou fragmentaires du squelette axial et appendiculaire non associés à des éléments cranio-dentaires. Il en résulte que plusieurs aspects fonctionnels et paléobiologiques du squelette postcrânien de P. robustus restent à préciser. Au moyen de la microtomographie à rayons X, de l'imagerie virtuelle et d'analyses quantitatives en deux-trois dimensions, nous avons entrepris un projet de recherche visant à explorer, extraire et les patrons d'organisation endostructurale de spécimens fossiles communément, ou préliminairement, attribués à P. robustus. Sur une base comparative, nous visons à (i) identifier quelques caractéristiques osseuses endostructurales propres à ce taxon, qui pourraient fournir un cadre de référence pour l'attribution de spécimens fossiles isolés; (ii) déconstruire l'environnement biomécanique ayant façonné l'arrangement de l'os cortical et trabéculaire au niveau des articulations du coude, de la hanche et du genou; (iii) évaluer le degré de variation et, dans la mesure du possible, les différences liées au sexe et à l'âge. L'échantillon étudié comprend quatre huméri distaux (TM 1517g, SK 24600, SKX 10924, SKX 34805), cinq fémurs proximaux (SK 82, SK 97, SK 3121, SKW 19, SWT1/LB-2), une patella (SKX 1084), des éléments additionnels échantillonnant l'assemblage TM 1517 (l'ulna proximale TM 1517e, la phalange distale d'hallux TM 1517k) et deux ilia (TM 1605, SK 50) provenant des sites de Kromdraai et Swartkrans. [...] / The Early Pleistocene taxon Paranthropus robustus, represented by the holotype TM 1517, was established in 1938 by the paleontologist R. Broom following the discovery of craniodental and postcranial remains at the cave site of Kromdraai, in Gauteng, South Africa. Since, other Southern African sites have contributed to the extension of its hypodigm, providing evidence for its chronological overlap in the macro-region with representatives of the taxa Australopithecus and Homo. As species identification in the hominin fossil record is commonly based on the comparative assessment of craniodental anatomy and morphological variation, the rarity in the hominin-bearing South African cave assemblages of unambiguously associated craniodental and postcranial remains usually complicates the task of identifying isolated and fragmentary elements from the axial and the appendicular skeleton. Consequently, different functionally- and paleobiologically-related aspects of the P. robustus postcranial skeleton remain poorly known. By means of techniques of high resolution X-ray micro-tomography and virtual imaging coupled with two-three-dimensional quantitative analyses, in this research project we explored, extracted and assessed the patterns of endostructural organisation in some fossil specimens commonly, or tentatively, attributed to P. robustus. On comparative ground, we aim at (i) identifying some endostructural bony features characteristic of this taxon, if any, thus tentatively providing a reference framework for the attribution of isolated fossil specimens; (ii) deconstructing the biomechanical (loading) environment having shaped the cortical and cancellous bone arrangement at the elbow, the hip, and the knee joints; (iii) assessing variation and, whenever possible, sex- and age-related differences. The investigated sample consists of four distal humeri (TM 1517g, SK 24600, SKX 10924, SKX 34805), five proximal femora (SK 82, SK 97, SK 3121, SKW 19, SWT1/LB-2), a patella (SKX 1084), some additional elements from the assemblage labelled TM 1517 (the proximal ulna TM 1517e, the distal hallucial phalanx TM 1517k), and two ilia (TM 1605, SK 50) from the sites of Kromdraai and Swartkrans. [...]

M.Phil. (Anthropology) / The primary aim of this study was to undertake the description and analysis of the manual and pedal hominin phalanges from Drimolen, South Africa. The specimens were contextualized by examining their counterparts in a series of extant and extinct specimens. As Drimolen preserves the remains of both Paranthropus robustus and early Homo, it provides an opportunity to contribute to our understanding of morphological variation and differences between these taxa, as well as providing an important first step in conceptualizing their evolutionary history and palaeobiology. The first section focused on the manual and pedal phalanges, while the second focused exclusively on the first metatarsal. Numerous studies have analyzed Plio-Pleistocene manual and pedal phalanges to evaluate tool-related behaviours and locomotion in early hominins. In this dissertation nine phalanges were described and analyzed for the first time. The manual specimens consist of one proximal (DNH 9), two proximal pollical (DNH 116 and DNH 119), four intermediates (DNH 48, DNH 63, DNH 65 and DNH 66) and one distal pollical phalanx (DNH 13). There is currently only one pedal proximal phalanx (DNH 117). As at Swartkrans, assignment of postcranial elements was hampered by the fact that two hominin species have been found at the site, namely Paranthropus robustus and early Homo. To analyze the specimens, multivariate statistics (PCA and CVA) were conducted on the specimens using raw and size-adjusted data. This was done within the context of a large extinct and extant dataset to compare size and shape data. In general, PCA and CVA yielded similar results but only the raw data was useful in discriminating between taxa. There was poor discrimination in the analyses based upon size-adjusted data because of the huge degree of overlap between fossil and extant taxa. Consequently, results were not diagnostic and it wasn’t possible to assign specimens confidently to either Paranthropus or Homo. This was exacerbated by the isolated nature of the remains, the presence of two hominin taxa and taxonomic uncertainties of several Swartkrans phalanges. Despite these difficulties, these specimens do provide insight into the degree of morphological variation present in the phalanges from the Plio-Pleistocene of South Africa. The second section described the fragmentary first metatarsal and quantified it by using laser scanning and calculating the curvature of the proximal articular surface. Univariate statistics were then calculated in order to examine the degree of curvature between each of the extant taxa and whether these differences were statistically significant. Finally, a simple bivariate plot was generated using the curvature results which showed that this joint surface was most curved in chimpanzees and western gorillas, moderately curved in eastern gorillas, and flattened in modern humans and baboons. Highly curved joint surfaces in this region suggest a more mobile hallux, whereas flattened surfaces suggest reduced joint mobility. The fossil specimens SK 1813, STW 573, STW 595 and OH-8 all grouped closely with modern humans; A.L. 333-54 and SKX 5017 grouped with chimpanzees, while DNH 115 grouped with eastern gorillas. Overall, these results indicate that SKX 5017 was the most curved of the South African specimens and is attributed to Paranthropus (Susman, 1988). It grouped closely with DNH 115 which suggested that climbing activities may have continued to play an important role in the behavioral repertoire of these individuals during the Plio-Pleistocene.

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