The SKX 1084 hominin patella from Swartkrans Member 2, South Africa : An integrated analysis of its outer morphology and inner structure
- Authors: Cazenave, Marine , Oettlé, Anna , Thackeray, John Francis , Nakatsukasa, Masato , De Beer, Frikkie , Hoffman, Jakobus , Macchiarelli, Roberto
- Date: 2019
- Subjects: Fossil hominins , Knee joint , Cortical bone
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/401171 , uj:33514 , Citation: Cazenave, M. et al. 2019. The SKX 1084 hominin patella from Swartkrans Member 2, South Africa : An integrated analysis of its outer morphology and inner structure. C. R. Palevol, 18:223–235. https://doi.org/10.1016/j.crpv.2018.06.002
- Description: Abstract: SKX 1084 is an isolated partial patella from Swartkrans Member 2, South Africa, attributed to a small-bodied Paranthropus robustus. This study provides complementary information on its outer conformation and, for the first time for a fossil hominin patella, documents its inner structure in the perspective of adding biomechanically-related evidence to clar- ify its identity. We used X-ray micro-tomography to investigate SKX 1084 and to extract homologous information from a sample of 12 recent human, one Neanderthal, and two adult Pan, patellae. We used geometric morphometrics to compare the outer equatorial contours. In SKX 1084, we identified two cancellous bony spots suitable for textural assess- ment (trabecular bone volume fraction, trabecular thickness, degree of anisotropy), and two related virtual slices for measuring the maximum cortico-trabecular thickness (CTT) of the articular surface. SKX 1084 shows a more complex articular shape than that for Pan, but still simpler than typical in Homo sapiens. At all sites, its CTT is thinner compared to Pan and approaches the condition in humans. This is also true for the expanded volume of the cancellous network. However, at both investigated spots, SKX 1084 is systematically intermediate between Homo and Pan for trabecular bone volume fraction and trabecular thickness, a pattern already shown in previous analyses on other Paranthropus postcranial remains...
- Full Text:
Microfocus X-ray tomography as a method for characterising macro-fractures on quartz backed tools
- Authors: Pargeter, Justin , Bam, Lunga , De Beer, Frikkie , Lombard, Marlize
- Date: 2017
- Subjects: Hunting weaponry , Micro-XCT scanning , Quartz
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/260555 , uj:27439 , Citation: Pargeter, J. et al. 2017. Microfocus X-ray tomography as a method for characterising macro-fractures on quartz backed tools. South African Archaeological Bulletin 72 (206): 148–155, 2017.
- Description: Abstract: Here we present the first assessment of microfocus X-ray tomography (micro-XCT) as an analytical technique to generate data about macro-fractures on small quartz backed tools similar to those currently held to represent the oldest known evidence for bow hunting. Our experimental results are derived from 21 replicated quartz backed tools randomly selected from a population (n=218) that were broken in a controlled hunting context. We used 3D data obtained from micro-XCT scans to identify macro-fractures and to derive more accurate measurements for these fractures. Our results demonstrate that the micro-XCT technique overcomes reflected-light challenges associated with analysing quartz through conventional macro-fracture approache s. We were able to increase the total observed macrofracture sample by 33% compared with conventional approaches using a hand-lens. Whereas macro-fracture data could be refined, the additionally gained data did not change interpretations obtained from a conventional macro-fracture analysis. It did, however, marginally change the degree of significance in differences between the different applications. During this study, we also detected micro-fracture features, such as possible fracture wings and microscopic linear impact traces (MILTs).With further studies, the morphometric traits of these micro-fracture features could be useful for distinguishing between ancient weapon-delivery systems.
- Full Text:
Life on a Mesoarchean marine shelf – insights from the world’s oldest known granular iron formation
- Authors: Smith, Albertus J. B. , Beukes, Nicolas J. , Gutzmer, Jens , Johnson, Clark M. , Czaja, Andrew D. , Nhleko, Noah , De Beer, Frikkie , Hoffman, Jakobus W. , Awramik, Stanley M.
- Date: 2020
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/464407 , uj:41488 , Citation: Smith, A.J.B. et al. 2020. Life on a Mesoarchean marine shelf – insights from the world’s oldest known granular iron formation. , DOI: https://doi.org/10.1038/s41598-020-66805-0
- Description: Abstract: The Nconga Formation of the Mesoarchean (~2.96–2.84 Ga) Mozaan Group of the Pongola Supergroup of southern Africa contains the world’s oldest known granular iron formation. Three dimensional reconstructions of the granules using micro-focus X-ray computed tomography reveal that these granules are microstromatolites coated by magnetite and calcite, and can therefore be classified as oncoids. The reconstructions also show damage to the granule coatings caused by sedimentary transport during formation of the granules and eventual deposition as density currents. The detailed, three dimensional morphology of the granules in conjunction with previously published geochemical and isotope data indicate a biogenic origin for iron precipitation around chert granules on the shallow shelf of one of the oldest supracratonic environments on Earth almost three billion years ago. It broadens our understanding of biologically-mediated iron precipitation during the Archean by illustrating that it took place on the shallow marine shelf coevally with deeper water, below-wave base iron precipitation in micritic iron formations.
- Full Text:
Life on a Mesoarchean marine shelf – insights from the world’s oldest known granular iron formation
- Authors: Smith, Albertus J. B. , Beukes, Nicolas J. , Gutzmer, Jens , Johnson, Clark M. , Czaja, Andrew D. , Nhleko, Noah , De Beer, Frikkie , Hoffman, Jakobus W. , Awramik, Stanley M.
- Date: 2020
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/464408 , uj:41489 , Citation: Smith, A.J.B. et al. 2020. Life on a Mesoarchean marine shelf – insights from the world’s oldest known granular iron formation. , DOI: https://doi.org/10.1038/s41598-020-66805-0
- Description: Abstract: The Nconga Formation of the Mesoarchean (~2.96–2.84 Ga) Mozaan Group of the Pongola Supergroup of southern Africa contains the world’s oldest known granular iron formation. Three dimensional reconstructions of the granules using micro-focus X-ray computed tomography reveal that these granules are microstromatolites coated by magnetite and calcite, and can therefore be classified as oncoids. The reconstructions also show damage to the granule coatings caused by sedimentary transport during formation of the granules and eventual deposition as density currents. The detailed, three dimensional morphology of the granules in conjunction with previously published geochemical and isotope data indicate a biogenic origin for iron precipitation around chert granules on the shallow shelf of one of the oldest supracratonic environments on Earth almost three billion years ago. It broadens our understanding of biologically-mediated iron precipitation during the Archean by illustrating that it took place on the shallow marine shelf coevally with deeper water, below-wave base iron precipitation in micritic iron formations.
- Full Text: