Palaeontologia africana

Now showing 1 - 3 of 3

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.
Preservation and interpretation of pollen in hyaena coprolites: taphonomic observations from Spain and southern Africa
(Bernard Price Institute for Palaeontological Research, 2003) Scott, Louis; Fernandez-Jalvo, Yolanda; Carrion, Jose; Brink, James
A survey of palynological research on hyaena coprolites from 10 fossil sites in southern Africa and 4 from Spain shows that coprolites from 10 out of the 14 sites contained fossil pollen. Pollen-bearing coprolites are generally richer in pollen than the surrounding sediments. Provisionally it seems that the sites with poor or no pollen in coprolites are relatively old or have been exposed to wet and dry moisture fluctuations, namely Makapansgat, Gran Dolina, Redcliff Cave and Erfkroon. This suggests that conditions during their long histories eventually destroyed pollen through oxidation associated with regular saturation of sediments. The composition of pollen spectra and preservation of pollen grains from coprolites is compared with that in fresh hyaena dung. SEM studies suggest that pollen grains in fresh dung and in fossil coprolites if preserved under suitable cave conditions, are generally well preserved with little damage. The damage traits require further systematic investigation in order to assess their taphonomic significance but selective destruction of pollen through ingestion, if any, seems to be light. Of particular interest to palaeoenvironmental studies is the observation that pollen assemblages preserved in hyaena dung are likely to provide relatively unbiased characterizations of vegetation representative of the wide surroundings in which the hyaenas were active. This implies that where pollen was relatively wellpreserved in coprolites, it can provide palaeoenvironmental information extending beyond the immediate environs of the site in which they were found. Any possible bias introduced through behaviour-related pollen trapping is, however, difficult to exclude.
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.

Palaeontologia africana

Browse

Filters

Settings

Sort By

Results per page

Search Results