3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item Palynology of a coal seam in Karoo deposits of Botswana and correlation with southern African coal-bearing strata(2010-12-02) Barbolini, NatashaA significant amount of palynological work has been done on southern African coal seams in the Ecca Group, but as yet there is little consensus on how these areas relate to each other. This study investigated the palynology of a coal seam from Mmamantswe (Mmamabula area), Botswana, approximately 70 km north-east of Gaborone. A total of 124 samples were taken from two borehole cores and subjected to acid preparation, oxidation and acetolysis. Coal samples were found to be barren of palynomorphs. Fifty carbonaceous mudstones and siltstone samples yielded twenty-two productive samples. A thermal alteration index of 3.0-3.5 was assigned for the sediments. Palynomorph diversity was high, with 64 genera and 90 species present, dominated by trilete and alete spores. This indicates a parent flora of mostly lower order lycopods, sphenophytes and ferns. Non-taeniate bisaccate and monosaccate pollens were scarce, and striates extremely rare (only two species), suggesting an autochthonous origin for the coal swamp. The Mmamantswe core was sub-divided into five microfloral assemblage zones. A transition from monosaccate dominance in the lower part of the core, to equal numbers of monosaccates and non-taeniate bisaccates in the upper part of the core, was seen. As the Mmamantswe palynoflora possesses elements of both the Late Carboniferous glacial floras and the mid-Permian coal floras, it is thought to represent a cross-over assemblage dating to soon after the Permo-Carboniferous boundary (Sakmarian and Early Artinskian). The Mmamantswe assemblage can be correlated with Assemblage Zones II and III of Falcon (1975a); Biozones B and C of MacRae (1988); and Zones 1, 2 and 3 of Anderson (1977) but does not fit well into any existing biozonation. The Mmamantswe palynoflora was most similar to that of Milorgfjella, Dronning Maud Land, Antarctica (Larrson et al. 1990) and the No. 2 Seam, Witbank, South Africa (Falcon 1989). Taphonomic controls on palynomorph preservation suggest that future studies should also attempt to focus on Permian sediments not containing coal, as microfloral assemblages from coal seams tend to be autochthonous, and subject to local climatic influences. Accordingly they are not as useful for inter-basinal correlation across Gondwana.Item A taxonomic revision of the genus Procolophon and the phylogenetic relationships of Procolophonoid reptiles(2008-03-18T08:54:02Z) Martinez, Juan Carlos CisnerosABSTRACT This study presents a taxonomic revision of some procolophonoid parareptiles and a detailed, global analysis of procolophonid intrarelationships. The poorly known genus Candelaria, from the Middle Triassic of Brazil, is identified on the basis of new material as an owenettid, rather than a procolophonid as previously thought. Thus, Candelaria represents the youngest owenettid and the first member of this group from South America. The cranium of Candelaria is also remarkable for having temporal fenestrae, and the significance of this character within the Parareptilia is discussed. Based on a comprehensive review of specimens referred to different Procolophon species, it is proposed that only the type species, Procolophon trigoniceps, is valid. Thus, Procolophon specimens from Brazil, South Africa, and Antarctica are all referable to P. trigoniceps. Consequently, P. trigoniceps has one of the broadest known geographic ranges among Triassic tetrapod species. A comprehensive cladistic analysis of procolophonids more firmly resolves the relationships within that group. The analysis reveals that Procolophoninae and Leptopleuroninae are valid monophyletic groups, whereas Spondylolestinae is paraphyletic. The species formerly assigned to the genus ‘Thelegnathus’ from the Middle Triassic of South Africa, and those assigned to ‘Eumetabolodon’ from the Lower-Middle Triassic of China, are paraphyletic. The poorly known Spondylolestes from the Dicynodon Assemblage Zone of South Africa is considered valid and possibly represents the only Permian procolophonid in Gondwana. A new species, Kitchingnathus untabeni, is identified in the Lystrosaurus Assemblage Zone of South Africa. It is a basal member of the Procolophonidae and co-occurs with Procolophon in the Upper Katberg Formation. The new taxon is characterized by the presence of a large number of thin, bicuspid teeth. Character optimisation indicates that bicuspid teeth were acquired independently in K. untabeni, and hence originated twice during procolophonid evolution. A review of procolophonid records worldwide reveals a fossil hiatus for members of this group in the Ladinian and most of the Carnian.