3. Electronic Theses and Dissertations (ETDs)

Now showing 1 - 4 of 4

Virtual reconstruction and description of the lower face definition of STW498- a Sterkfontein: australopithecus
(2019) Reddy, Shani
On the 30th of September 1988, a team directed by Alun Hughes and Phillip Tobias excavated portions of a skull of an Australopithecus (StW 498) from square P/41 at Sterkfontein Member 4. The fossil was found at a depth of 17’9” to 19’9” ft below datum. StW 498 consists of cranial vault fragments, relatively complete left and right maxillae, and relatively complete left and right mandibles. While the mandibular and maxillary dentition is complete, the right mandible and right maxilla are fragmentary and anatomically displaced. Because of its fragile condition, a physical reconstruction was not advisable. The primary purpose of this research was to virtually reconstruct StW 498 using high resolution image data acquired from microCT scanning and to describe the morphology of the specimen. The reconstruction of StW 498 provided a valuable opportunity to conduct quantitative analyses and qualitative observations in order to place it within a framework of hominid cranio-dental variation, focusing in particular on Australopithecus africanus, Australopithecus prometheus and Paranthropus robustus. Based on the internal morphology and size of the dental arcade, StW 498 is a young adolescent male. The specimen exhibits dental pathology, specifically crowding of the maxillary dentition which resulted in the atypical eruption and position of the left maxillary canine. However, contra to the suggestion by Schwartz and Tattersall (2005), the right lower canine reflects taphonomic disruption of the intact anatomy rather than an eruptive anomaly. The results of this research indicate that StW 498 is morphologically more similar to specimens attributed to A. prometheus, such as MLD 9, StW 252, and StW 573, than A. africanus and P. robustus. Keywords: Australopithecus, Sterkfontein, Virtual reconstruction
Fossilised dermal tissue associated with Australopithecus sediba
(2017) Keeling, Rachelle
The near-complete Plio-Pleistocene-aged Australopithecus sediba hominin specimens from the Malapa site, South Africa were analysed to determine whether soft tissue in the form of fossilised skin might have been preserved. The taphonomic condition of the fossils suggests rapid burial, lack of predation, but with some insect damage, making the preservation environment at Malapa exceptional. Any potential soft tissue found with the hominins, represented by Malapa Hominid 1 (MH1) and Malapa Hominid 2 (MH2), was valuable to examine because such preservation is unrecognised in the early hominin record. Two primary specimens were analysed – a sample associated closely with the cranium of MH1 and a specimen associated with the mandible of MH2. A multidisciplinary approach that combined morphological techniques (optical coherence tomography, three-dimensional laser scans, micro-CT scans and light microscopy) in association with molecular imaging (Raman spectroscopy and Fourier Transform Infrared) was used to investigate whether original organics might be recovered. A null hypothesis was formulated and based on the findings from the six non-destructive techniques it was rejected. Soft tissue had seemingly been preserved, in a fossilised form, with the Malapa hominin samples based on the findings from the six non-destructive techniques.
Shape and size variability in lower second molars of extant hominoids and extinct hominin species with particular reference to modern homo sapiens and its potential for use as an analogue species in the context of fossil hominin dental variability comparisons
(2018) Dykes, Susan Jane
Teeth make up the bulk of hominin fossil material and are useful in taxonomic assessments. In this thesis, discriminant function, principal components and randomised CV analyses on large samples of lower second molars (n=778) from five extant reference species, both sexually dimorphic and non-dimorphic, provide estimates of ranges of size-shape variability to be expected within a single species. However, there is evidence that diet-driven tooth-size reduction and cusp simplification has expanded the ranges of shape and size variability of Homo sapiens in some populations, in areas exposed to soft, undemanding diets since the transition to agriculture and increased use of cooking, food processing and ceramics from about 12500 years ago. Molar size and shape changes are less evident in communities retaining a hunter-gatherer subsistence strategy, requiring strong dentognathic structures with robust teeth to masticate harder, tougher foodstuffs. These factors, driving divergent variability in tooth size and shape, are unique to modern humans. Using a novel mathematically-based landmarking methodology, developed to allow the inclusion of severely worn teeth, intra-species size-shape variability was assessed from 63 lower M2s representing nine African Plio-Pleistocene species. The first hypotheses tested in this thesis address the question of which extant hominoid species might be suitable for use as analogue species for comparisons with fossil hominin molars, and whether uniquely modern-human anomalous size-shape variability exhibited by lower second molars might disqualify modern Homo sapiens for such analyses. Secondly, where lower second molar size-versus-shape variability ratios measured for fossil species do not match those of either a sexually dimorphic or a non-dimorphic extant species, evaluations are made as to whether samples attributed to single hominin species might actually represent specimens from more than one species present in the relevant assemblages, whether sexual dimorphism may have been greater in fossil species than in extant species, and whether some individual specimens attributed to any fossil species might be misclassified. Results of the analyses indicate that uniquely human subsistence strategy divergences are identifiable in the size-shape variability of lower second molars. Furthermore, specimens representing Australopithecus afarensis, Australopithecus africanus and Paranthropus robustus in this study exhibit very high variability and may indicate the presence of more than one species in their respective assemblages.
The field of human evolution within evolutionary biology and anthropology: historical and epistemological analyses since inception
(2013-08-28) Delisle, Richard G

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