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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The systematics, palaeobiology and palaeoecology of Kambara taraina sp. nov. from the Eocene Rundle Formation, Queensland

Buchanan, Lucas Allen January 2009 (has links)
A recently excavated bonebed in the Kerosene Creek Member of the Eocene Rundle Formation has yielded an abundance of crocodilian material. Fossils representing nearly all osteological elements, both cranial and postcranial, have been recovered and described. The described cranial remains are clearly indicative of a new species, Kambara taraina. This new species belongs to the earliest known genus of an endemic Australasian group, the Mekosuchinae, a group which radiated in Australasia during the mid to late Cenozoic and utilized various morphologies to exploit a range of ecologic niches. The early Cenozoic remains poorly known with respect to vertebrates and so this discovery of a new Eocene form is significant, showcasing a large sample of well-preserved material. Cranial material reveals functional divergence among the species of early mekosuchines, reflecting subtle partitioning of feeding strategies. The enlarged insertion area in the caudoventral part of the surangular suggests an increase in adductor mass resulting in a greater bite force. Bite marks in a large chelid plastron, attributable to K. taraina, support this inference. K. taraina is further distinguished from other Kambara species by the possession of a fully interlocking dentition and a decreased number of alveoli. Analysis of the postcranial anatomy suggests an overall generalist crocodilian body plan. However, aspects of the tarsal elements suggest that K. taraina may have been more adept at either terrestrial or shallow water ‘bottom-walking’ locomotion than other generalist aquatic crocodilians. Due to the completeness and size of the sample, description of the Kerosene Creek Member postcranial elements provides a standard reference text for mekosuchine postcranial anatomy, setting a precedent for consideration of postcranial anatomy in a field where little previous work has been done. Functional morphologic analyses of both the cranium and postcranium of K. taraina along with its palaeoenvironmental context suggest that this crocodile fed foraged along the shallow lake margins, operating as an opportunistic ambush predator. Macroscopic and radiographic analyses have revealed pathologic deformities in some elements demonstrating the presence of infection, neoplasm, and fractures that likely resulted from intraspecific fighting in K. taraina. A severely deformed left humerus has been shown to have suffered chronic osteomyelitis, a condition that, although well-documented in the fossil record, has not been previously reported for Australasian fossil crocodiles. A left fibula possesses evidence of neoplastic growth, tentatively attributed to a vascular tumour. The legion is expansile, exhibiting cortical thinning and formed coarse trabeculae in the medullary cavity. This is the first report of neoplasm in a fossil crocodilian from the southern hemisphere, and the first report of a bony vascular tumour in a crocodile. Thorough description of nearly all osteological elements has allowed a comprehensive scoring of K. taraina for cladistic analysis. Preliminary analyses supported the allocation of Mekosuchinae to within Crocodylidae. However, resolution was insufficient to determine taxon relationships within Mekosuchinae and requires a far more thorough analysis. This preliminary analysis demonstrates the inadequacy of current mekosuchine phylogenetics and the necessity for greater attention to be given to the lack of transparency in published cladistic analyses.
2

An Application of Sequence Stratigraphy in Modelling Oil Yield Distribution: The Stuart Oil Shale Deposit, Queensland, Australia

Pope, Graham John January 2005 (has links)
The Stuart Oil Shale Deposit is a major oil shale resource located near Gladstone on the central Queensland coast. It contains an estimated 3.0 billion barrels of oil in place in 5.6 billion tonnes of shale. Commissioning of a plant capable of producing 4,500 barrels per day has recently commenced. The shale is preserved in Tertiary age sediments of The Narrows Beds in the southern part of The Narrows Graben. The oil shale sequence consists of repetitive cycles composed of oil shale, claystone and lesser carbonaceous oil shale in the 400 metre thick Rundle Formation. The formation is the main oil-shale bearing unit in the preserved half-graben sequence up to 1,000 metres thick. Previous studies on the lacustrine sedimentology of the Rundle Oil Shale Deposit in the northern part of The Narrows Graben have recognised eight facies that exhibit unique and recognisable cycles. The cycles and sequence for the Kerosene Creek Member of the Rundle Formation is correlatable between the Rundle and Stuart deposits. The nature of these facies and the cycles is reviewed in some detail. In conjunction with the principles of sequence stratigraphy, the ideal oil shale cycle is described as the equivalent of a parasequence within a lacustrine system. The lacustrine parasequence is bounded by lacustrine flooding surfaces. The organic material in the oil shale consists of both Type I (algal dominated) and Type III (higher plant matter dominated) kerogen. Where Type I kerogen dominate, oil yields greater than about 100 litres per tonne are common. In contrast where Type III kerogens are dominant, yields above 100 litres per tonne are rare. The variation in oil yield is described for the Stuart lacustrine system. The variation is consequent on the balance between production, preservation and degradation of the kerogen in the parasequences within systems tracts. A system for the recognition of oil shale deposition in terms of lacustrine systems tracts is established based on oil yield assay parameters and the assay oil specific gravity. The oil yield and oil specific gravity variation within the Rundle Formation is modelled by member and the nature and distribution of oil yield quality parameters in terms of the contribution of organic and inorganic source material are described. The presence of significant oil yield (greater than 50 litres per tonne) is dependent on the dominance of lacustrine transitional systems tracts and to a lesser extent, lacustrine highstand systems tracts within the parasequence sets deposited in a balanced lake system in a generally warm wet climate during the middle to late Tertiary.

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