Volume 48 December 2013

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https://wiredspace.wits.ac.za/handle/10539/13307

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    Letter from the Editor
    (2013-12-18) Choiniere, Jonah N
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    Fluctuations in Miocene climate and sea levels along the southwestern South African coast: inferences from biogeochemistry, palynology and sedimentology
    (Evolutionary Studies Institute, University of the Witwatersrand, 2013-12-18) Sciscio, Lara; Neumann, Frank H.; Roberts, Dave; Tsikos, Harilaos; Scott, Louis; Bamford, Marion
    The largest deposit of excellently preserved Mio-Pliocene vertebrate faunas in South Africa is located at the well known Langebaanweg (LBW) site along South Africa’s west coast in the southwestern Cape. This research deals with a core (BH2) drilled at Langebaanweg ‘E’ Quarry, which captures Miocene fluvial deposits that unconformably underlie the Mio-Pliocene deposits. The aim of the study is to constrain fluctuations in climate and ecosystems in the region during the Miocene, using a combination of sedimentology, palynology, and biogeochemistry. The latter is a novel application and includes bulk C and N isotope measurements as well as branched GDGT (glycerol dialkyl glycerol tetraether) membrane lipid compositions of the organic fraction of the core. The mean annual temperature (MAT) at time of deposition and ambient pH values were calculated using the Methylation index of Branched Tetraethers (MBT) and Cyclization ratio of Branched Tetraethers (CBT) proxies. The core samples analysed spanned a depth interval of 17–33 m and had MATs ranging between 12.4°C and 26.6°C and pH range from 4.4 to 6.4. Furthermore, samples showed a low variance and light d13C distribution (from –25.52‰ to –24.27‰) and overall low C/N ratios. Palynological investigation supplemented earlier similar studies, reaffirming alternating sequences of tropical and subtropical elements including wetland taxa and complementing calculated MAT results. Pollen results from the lowermost subsection indicated a species-rich tropical/subtropical Podocarpus dominated forest with MATs at 16.2°C. The pollen-bearing middle subsection shows initially subhumid conditions, with MATs between 15.4 and 26.6°C, similar to the bottom of the section with high Podocarpaceae percentages, low Restionaceae and aquatics. Above this, local taxa, e.g. Restionaceae and algae increase, and a marine influence is indicated by abundant dinoflagellates. The uppermost subsection from a depth of 7.20–7.60 m shows similar conditions (with little marine influence) to that of the lower part of the middle subsection II. Biochemical and sedimentological data are not available for the uppermost subsection. The results suggest that regional Miocene climate showed high amplitude fluctuations (possibly driven by orbital forcing as seen in marine cores), underscoring the potential of biogeochemistry for unravelling past climates and ecosystems.
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    Cretaceous faunas from Zululand and Natal, South Africa. Texasia cricki Spath, 1921 (Cephalopoda: Ammonoidea) an early Santonian marker fossil from the Mzamba Formation of the Eastern Cape Province
    (Evolutionary Studies Institute, University of the Witwatersrand, 2013-12-18) Kennedy, William James; Klinger, Herbert Christian
    The type material of ‘Gen. nov. (Muniericeras?)’ cricki Spath, 1921, from the Santonian part of the Mzamba Formation , Eastern Cape Province, is revised, and referred to Texasia Reeside, 1932, of which Lehmaniceras Collignon, 1966 is a subjective junior synonym. Lehmaniceras sornayi, L. acutum, L. macer, L. pingue, L. ultimum and possibly L. gracile of Collignon, 1966, originally described from Madagascar, are further synonyms, as is Barroisiceras umzambiensis van Hoepen, 1968, which is based on a single specimen from Mzamba. The species occurs in the lower part of the Zone of Texanites hourcqi in Madagascar, confirmed here as lower, rather than middle, Santonian.
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    Mustelid and viverrid remains from the Pleistocene site of Cooper’s D, Gauteng, South Africa
    (2013-12-18) O'Regan, Hannah J.; Cohen, Brigette F.; Steininger, Christine M.
    Fossil mustelids and viverrids are rare in the African Pleistocene fossil record. The careful examination of sieved sediments from the well-dated Cooper’s D locality in Gauteng has revealed six new mustelid and viverrid specimens. These represent three uncommon genera – two mustelids, Propoecilogale bolti and Mellivora capensis, and a viverrid, Civettictis cf. civetta. We describe and figure these six specimens here. Cooper’sD is only the fourth African locality at which P. bolti has been identified, and it is the first of the Witwatersrand sites to contain remains of the African civet.
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    Charting the fossils of the Great Karoo: a history of tetrapod biostratigraphy in the Lower Beaufort Group, South Africa
    (Evolutionary Studies Institute, University of the Witwatersrand, 2013-12-18) Day, Mike
    The interest in the fossil remains of the Beaufort Group and their stratigraphic significance goes back as far as the earliest geological studies in South Africa in the early 19th century. By the 1890s, the understanding of fossil distributions in the sedimentary rocks of the Karoo allowed the formulation of the first tetrapod biostratigraphic subdivisions. Since the beginning of the 20th century, the highest resolution subdivisions of the mostly undifferentiated fluvial sediments of the Beaufort Group have been biostratigraphic. More recent biostratigraphic studies in the Lower Beaufort Group have been crucial in understanding terrestrial ecological change in the Middle and Late Permian, and continue to be a leading area of research in South Africa palaeontology.
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    Cranial morphology and taxonomy of South African Tapinocephalidae (Therapsida: Dinocephalia): the case of Avenantia and Riebeeckosaurus
    (Evolutionary Studies Institute, University of the Witwatersrand, 2013-12-18) Guven, Saniye; Rubidge, Bruce S.; Abdala, Fernando
    Tapinocephalid dinocephalians comprise a large component of Middle Permian herbivorous tetrapod biodiversity and are significantly abundant in the Karoo rocks of SouthAfrica. In order to understand the effect of the alleged Middle Permian extinction in the terrestrial record of amniotes a clear understanding of the taxonomic diversity of this group is essential. The tapinocephalids Avenantia kruisvleiensis and Riebeeckosaurus longirostris have in the past been distinguished by a set of characters, including differences in the snout length which was previously interpreted as a key diagnostic character. Further preparation of the material attributed to these species shows that the purported distinguishing characters, such as snout length, low intertemporal crest, and surface thickening of the parietal represent postmortem deformation (including distortion and weathering) or can be interpreted as individual or ontogenetic variation. Accordingly A. kruisvleiensis is synonimized with R. longirostris.