Wits Evolutionary Studies Institute (ESI)

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End date: 2019

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    Discovering Hominins - Application of Medical Computed Tomography (CT) to Fossil-Bearing Rocks from the Site of Malapa, South Africa.
    (Public Library of Science, 2015-12-18) Smilg, J.S.; Berger, L.R.; Smilg, Jacqueline S.
    In the South African context, computed tomography (CT) has been used applied to individually prepared fossils and small rocks containing fossils, but has not been utilized on large breccia blocks as a means of discovering fossils, and particularly fossil hominins. Previous attempts at CT imaging of rocks from other South African sites for this purpose yielded disappointing results. For this study, 109 fossil- bearing rocks from the site of Malapa, South Africa were scanned with medical CT prior to manual preparation. The resultant images were assessed for accuracy of fossil identification and characterization against the standard of manual preparation. The accurate identification of fossils, including those of early hominins, that were not visible on the surface of individual blocks, is shown to be possible. The discovery of unexpected fossils is reduced, thus lowering the potential that fossils could be damaged through accidental encounter during routine preparation, or even entirely missed. This study should significantly change the way fossil discovery, recovery and preparation is done in the South African context and has potential for application in other palaeontological situations. Medical CT imaging is shown to be reliable, readily available, cost effective and accurate in finding fossils within matrix conglomerates. Improvements in CT equipment and in CT image quality are such that medical CT is now a viable imaging modality for this palaeontological application.
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    (DURASPACE, 2005-08-17) Diol, Joe
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    Pleistocene vertebrate trace fossils of Robberg Nature Reserve
    (Evolutionary Studies Institute, 2019-12) Helm, Charles W.; Cawthra, Hayley C.; Hattingh, Rudolph; Hattingh, Sinèad; McCrea, Richard T.; Thesen, Guy H. H.
    More than 140 Late Pleistocene trace fossil sites have been identified in aeolianites and lithified foreshore deposits along a 350 kilometre stretch of the Cape south coast in South Africa. Robberg Nature Reserve lies within this area and contains a zone of concentration of such tracksites, which complement the Pleistocene vertebrate body fossil record and assist in shedding light on the palaeoenvironment and palaeoecology of the Palaeo-Agulhas Plain. Ichnofossil sites unique to or of special significance within Robberg Nature Reserve include a substantial palaeosurface exposure that allows an estimate of track density, the best-preserved rhinoceros trackway identified to date, very well preserved artiodactyl tracks in the formof natural casts, small equid tracks, large elephant transmitted tracks, and well preserved sub-surface golden mole burrows with a burrow chamber. Aeolianite layers at Robberg have recently been dated to Marine Isotope Stage (MIS) 3. Samples that we have obtained for dating from the main palaeosurface underlie these dated layers and are anticipated to contribute to the understanding of the Pleistocene geology of the Robberg Peninsula. The protected status of the area lends itself to conservation, replication, interpretation and education initiatives.
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    A comparison of hominin teeth from Lincoln Cave Sterkfontein L63 and Dinaledi Chamber South Africa
    (Academy of Science of South Africa, 2019-05) Brophy, J.K.; Irish, J.; Churchill, S.E.; de Ruiter, D.J.; Hawks, J.; Berger, L.
    Prior to the recovery of Homo naledi from the Dinaledi Chamber of the Rising Star Cave system, the Middle Pleistocene fossil record in Africa was particularly sparse. With the large sample size now available from Dinaledi, the opportunity exists to reassess taxonomically ambiguous teeth unearthed at the nearby site of Sterkfontein. Teeth recovered from Lincoln Cave South and area L/63 at Sterkfontein have been considered ‘most probably Homo ergaster’ and ‘perhaps Archaic Homo sapiens’, respectively. Given the similarities shared between Lincoln Cave, area L/63, and the Dinaledi Chamber with regard to climatic/geologic depositional context and age, two teeth from the former sites, StW 592 and StW 585 respectively, were compared with corresponding tooth types of H. naledi from the Dinaledi Chamber. The results of our study indicate that the Lincoln Cave and area L/63 teeth are morphologically inconsistent with the variation recognised in the H. naledi teeth. Significance: • The similar age and climatic/geologic depositional and post-depositional circumstances at Lincoln Cave South, area L/63 at Sterkfontein and the Dinaledi Chamber, Rising Star raise the possibility that these fossils might represent the same species. • The teeth StW 592 and StW 585 are not consistent with the variation evident in the known H. naledisample. • The results of the study do not add to the question of the existence of at least two species of the genus Homo living in close proximity to each other in South Africa at approximately the same time.
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    The Younger Dryas interval at Wonderkrater (South Africa) in the context of a platinum anomaly
    (Evolutionary Studies Institute, 2019-10-02) Thackeray, J. Francis; Scott, Louis; Pieterse, P
    Wonderkrater in the Limpopo Province in South Africa is a late Quaternary archaeological site with peat deposits extending back more than 30 000 years before the present. Palaeoclimatic indices based on multivariate analysis of pollen spectra reflect a decline in temperature identifiable with the Younger Dryas (YD). A prominent spike in platinum is documented in aWonderkrater sample (5614) with a mean date of 12 744 cal yr BP using a Bayesian model, preceding the onset of the YD cooling event. The YD platinum spike at Wonderkrater is the first to be observed in Africa in the southern hemisphere, supplementing new discoveries from Patagonia in South America, in addition to more than 25 sites with such platinum anomalies in the northern hemisphere. The observations from South Africa serve to strengthen ongoing assessments of the controversial YD Impact Hypothesis, whereby it is proposed that a meteorite or cometary impact contributed to a decline in temperature, associated inter alia with dispersion of atmospheric dust, mammalian extinctions and cultural changes.
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    Cranial morphology and phylogenetic relationship of the enigmatic dinocephalian Styracocephalus platyrhynchus from the Karoo Supergroup, South Africa
    (Evolutionary Studies Institute, 2019-09) Fraser-King, Simon W.; Benoit, Julien; Day, Michael O.; Rubidge, Bruces S.
    Styracocephalus platyrhynchus is an unusual dinocephalian therapsid, known only from a handful of specimens from the Tapinocephalus Assemblage Zone of South Africa. It has had a chequered taxonomic history, largely because it is characterized by cranial pachyostosis and the presence of horn-like structures that project posteriorly from the temporal region; these features are found in the clades Burnetiamorpha and Dinocephalia. Its affinities have been further obfuscated by a lack of well-preserved material. This paper presents a description of a well-preserved skull referable to Styracocephalus from the western Karoo Basin and provides a revised generic diagnosis for the genus. This study – incorporating comparative anatomy,CT scanning, and cladistic analysis – reveals new character information that was not evident from pre-existing Styracocephalus material, and incorporates this into a new phylogenetic analysis. Our analysis recovers Styracocephalidae as a well-supported, monotypic family within Tapinocephalia, which is characterized by: prominent pachyostotic nasal and supraorbital bosses; two posteriorly projecting crest-like protuberances comprising contributions by the postorbital, squamosal and tabular bones; weak lingual heels on the incisor and postcanine dentition present with a moderate upper and lower canine. As Styracocephalus is restricted to the upper part of the Tapinocephalus Assemblage Zone, it may be a useful biostratigraphic index taxon in future.
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    Systematic experiments to quantitatively assess image quality for CT scans of a Karoo tetrapod fossil
    (Evolutionary Studies Institute, 2019-08) Tshibalanganda, Muofhe; du Plessis, Anton; Le Roux, Stephan G.; Taylor, Wendy L.; Smith, Roger M. H.; Browning, Claire
    Over the past decade non-destructive, three-dimensional visualization and analysis of fossils using X-ray tomography has greatly advanced palaeontological studies worldwide. Micro-computed tomography (microCT) is now accepted as best practice in palaeontological studies to augment the anatomical description of newly discovered fossils. Despite advances in laboratory microCT hardware, software and skills of users, there is a lack of clear methodologies for scanning and analysing fossils. Here we report on a systematic and detailed study of the quantitative effects of the variation of different microCT scanning parameters on the image quality of an unprepared fossilized Karoo tetrapod skull and parts of the postcrania. Results indicate that voltage variations do not increase the contrast for the bone as one would expect, and the best image quality solution is found using high frame averaging and high X-ray flux (current). Although this study was limited to one specimen, the results may find a practical use for future studies involving similar fossils.
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    First occurrence of the dicynodont Digalodon (Therapsida, Anomodontia) from the Lopingian upper Madumabisa Mudstone Formation, Luangwa Basin, Zambia
    (Evolutionary Studies Institute, 2019-04) Angielczyk, Kenneth D.
    Digalodon is a rare emydopoid dicynodont first described from upper Permian rocks in the Karoo Basin of South Africa. During fieldwork in the upper Madumabisa Mudstone Formation of the Luangwa Basin (Zambia) in 2014, a small dicynodont skull was discovered that conforms very well to the recently revised diagnosis of Digalodon rubidgei, although some minor differences between the Zambian and South African specimens are apparent. The Zambian occurrence of Digalodon expands the known geographic range of the genus, which was previously limited to a small set of localities in the vicinity of the town of Graaff-Reinet (Eastern Cape). Based on historical specimens, Digalodon is thought to have a comparatively short stratigraphic range in the Balfour Formation that spans the boundary between the Cistecephalus and Daptocephalus assemblage zones. This observation may allow refinement of biostratigraphic correlations between the Karoo and Luangwa Basins, but discovery of more precisely-provenanced specimens in the Karoo is needed to fully assess Digalodon’s biostratigraphic utility.
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    Postcranial osteology of the neotype specimen of Massospondylus carinatus Owen, 1854 (Dinosauria: Sauropodomorpha) from the upper Elliot formation of South Africa
    (Evolutionary Studies Institute, 2019-04) Barrett, Paul M.; Chapelle, Kimberley E.J.; Staunton, Casey K.; Botha, Jennifer; Choiniere, Jonah N.
    Massospondylus carinatus Owen, 1854, from the earliest Jurassic upper Elliot Formation of South Africa, was one of the first dinosaurs to be described from Gondwana. It has been incorporated into numerous phylogenetic, palaeobiological and biostratigraphic analyses, is often viewed as an exemplar for understanding sauropodomorph anatomy and is a key taxon in studies of early dinosaur evolution. Since its initial description, numerous specimens have been referred to this species, ranging from isolated postcranial elements to complete skeletons with three-dimensional skulls. In addition,M. carinatus has been identified in areas outside of the main Karoo Basin. Surprisingly, however, there have been few attempts to define the taxon rigorously, so that the basis for many of these referrals is weak, undermining the utility of this abundant material. Here, we provide the first detailed postcranial description of the neotype specimen ofM. carinatus, use it as a basis for diagnosing the species on the basis of cranial, axial and appendicular characters, demonstrate that it represents an adult individual on the basis of osteohistology, and discuss ways in which these data can assist in providing a better understanding of Karoo-aged African dinosaur faunas.
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    A fossil chrysochlorid skull in the Ditsong National Museum of Natural History: Robert Broom’s missing specimen unearthed?
    (Evolutionary Studies Institute, 2019-04) Mason, Matthew J.; Bennett, Nigel C.; Pickford, Martin
    An unlabelled, fossilized skull of a golden mole from the Ditsong National Museum of Natural History, Pretoria, was examined through micro-computed tomography. Reconstructions show that the species in question has alveoli for nine teeth in each upper jaw, although only six teeth in total remain. The skull resembles those of the extant chrysochlorids Amblysomus and Calcochloris, which also have nine teeth, but in most respects it is closer to Amblysomus. The ear region, examined in detail, also proved to be very similar to that of Amblysomus. Damage to the teeth and palate are consistent with the brief descriptions of a fossil golden mole skull first mentioned by Robert Broom in 1948. This specimen, dating from the Plio-Pleistocene and provisionally identified as Proamblysomus antiquus, subsequently went missing. We argue that the skull described here is Broom’s lost specimen, but whether this fossil species really deserves generic distinction from extant groups remains unclear.