1 10 3 https://theses.otagogeology.org.nz/files/original/b3cf838895176024488220d13cddfe59.pdf 5f60902f6f1a140ff88d8342ced07b99 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Author last name Last name of the Author Boessenecker Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student Fordyce, R.E. Abstract The Abstract for this thesis The early evolution of toothless baleen whales (Chaeomysticeti) remains elusive despite a robust record of Eocene-Oligocene archaeocetes and toothed mysticetes. Eomysticetids, a group of archaic longirostrine toothless baleen whales fill in a crucial morphological gap between well-known toothed mysticetes and more modernized Neogene Mysticeti. Eomysticetids have been reported from South Carolina, USA, and Japan. Problematic fossils from New Zealand including "Mauicetus" lophocephalus Marples, 1956 and "Mauicetus" waitakiensis Marples, 1956, have been proposed as southern hemisphere eomysticetids. The fragmentary nature of this material has hampered interpretation of the relationships of these species. A large new collection of Eomysticetidae from the Oligocene Kokoamu Greensand and Otekaike Limestone of New Zealand permits reassessment of the skeletal anatomy, functional morphology, ontogeny, monophyly, and phylogenetic relationships of the family. This collection includes significant specimens including skulls, tympanoperiotics, mandibles, and postcrania of juveniles and adults. Discovery of new material similar to the "Mauicetus" of Marples permits referral of these species to the new genera Tohoraata and Tokarahia, recombined as Tohoraata waitakiensis and Tokarahia lophocephalus. More complete material of similar species Tohoraata raekohao and Tokarahia lophocephalus indicates that the two species of Tohoraata are stratigraphically separated whereas both species of Tokarahia were contemporaneous. The new genus and species Waharoa ruwhenua is represented by an ontogenetic series of skeletons that highlight the elongation of the palate during ontogeny; other morphofunctional aspects of the feeding apparatus suggest right whale-like skim feeding. The new genus and species Matapa waihao is the oldest and most archaic eomysticetid from New Zealand, indicating the presence of the family in the Southern Hemisphere by the earliest Chattian. Fragmentary specimens indicate the survival of eomysticetids to the Oligo-Miocene boundary or perhaps into the earliest Miocene, and the possible occurrence of the Japanese eomysticetid Yamatocetus in the Southern Hemisphere. Cladistic analysis confirms placement of the family Eomysticetidae as sister to crown Mysticeti. Eomysticetidae is for the first time recognized as being monophyletic; cladistic results indicate inclusion of Micromysticetus rothauseni. The Eomysticetidae were a specialized, worldwide, diverse, and short-lived Oligocene radiation of the earliest toothless mysticetes OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/5742">http://hdl.handle.net/10523/5742</a> OURArchvive access level Abstract Only Department The department where the student is studying primarily. Geology Thesis description Number of pages, maps, CDs, etc. xv, 431 pages A4 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Identifier An unambiguous reference to the resource within a given context 2015Boessenecker Creator An entity primarily responsible for making the resource Boessenecker, Robert W. (Bobby) Date A point or period of time associated with an event in the lifecycle of the resource 2015 Title A name given to the resource Anatomy, ontogeny, functional morphology, taphonomy, and phylogenetic relationships of archaic toothless mysticetes (Eomysticetidae) from the Oligocene of New Zealand Subject The topic of the resource Paleontology Baleen baleen whales Cetacea Eomysticetidae Evolution Functional Morphology Morph Mysticeti New Zealand Oligocene Ontogeny Paleontology phylogeny Taphonomy https://theses.otagogeology.org.nz/files/original/0b8bbde5209bd8ffb746b113ae637705.pdf d088af4f1cc96361ca75bfa659111da1 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Author last name Last name of the Author Cross Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student Prior, D.J. Abstract The Abstract for this thesis Ductile shear zones localise tectonic stresses and accommodate plate motions in the middle to lower crust and mantle, and control the strength of much of the Earth. Despite a common assumption that ductile shear zones deform under nominally steady-state conditions, changes in stress and strain rate are anticipated during shear zone formation and localisation, and in mid-crustal shear zones which are periodically loaded from above by earthquakes. Here, the microstructural response to changes in stress and strain rate is explored with particular emphasis on the evolution of grain size, crystallographic fabric and dominant deformation mechanism. A broad range of techniques have been applied, including electron backscatter diffraction (EBSD), titanium-in-quartz (TitaniQ) thermobarometry, numerical modelling of grain size evolution and Griggs apparatus experimentation. For context, quartzofeldspathic mylonites of the Alpine Fault zone (AFZ) of New Zealand have been studied and are used to relate numerical and laboratory studies to nature. During shear around rigid garnet porphyroclasts, quartz in the AFZ mylonites undergoes grain size reduction by dynamic recrystallisation in response to increasing stresses and strain rates adjacent to a porphyroclast. Meanwhile, quartz [c]-axes reveal increasing amounts of slip on rhomb <a> and prism <a> planes. These results are replicated in the laboratory by shear of quartz around alumina piston asperities, during which prism<a>slip becomes dominant and resistant to subsequent replacement as stresses reduce. Recrystallised quartz grain sizes in the AFZ mylonites are consistent with differential stresses of ~50 MPa, which are well replicated by finite element models using quartz rheological data. Quartz deformation in the AFZ mylonites ceased at around 500_C, as recorded by the preservation of grain boundary migration microstructures and titanium-in-quartz concentrations, which appear well equilibrated due to rapid grain boundary migration during deformation. Rates of grain size increase downshear of garnet porphyroclasts far exceed laboratory-measured rates of static annealing. This discrepancy probably reflects the additional contribution of internal strain-energy driven grain boundary migration to surface-energy driven grain growth, enhancing grain growth rates in favourably oriented grains at the expense and ‘elimination’ of unfavourably oriented grains. In experiments simulating rapid strain rate changes analogous to mid-crustal seismic stress cycling, plagioclase aggregates undergo rapid dynamic recrystallisation during a strain rate increase, and are remain weakened long after strain rates and stresses return to ambient levels. The longevity and degree of mechanical weakening depend on the rate of grain growth to re-establish steady-state conditions, and the dominant deformation mechanism. If dislocation creep is dominant throughout a strain rate perturbation, no mechanical weakening is observed. However, if grain size sensitive processes of diffusion creep and grain boundary sliding dominate, mechanical weakening is achieved. Grain size reduction in response to a stress increase is inferred to cause weakening of a crystallographic fabric through enhanced grain boundary sliding, though fabric weakening appears slow. In numerical models of grain growth during a postseismic stress and strain rate drop, rapid rates of grain growth are required to re-establish microstructural steady-state conditions on timescales equivalent to typical earthquake recurrence intervals. Despite this, dynamic grain growth rates calculated for natural AFZ quartz are sufficiently rapid to allow at least a partial return to steady-state during a typical 300-year AFZ interseismic period. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/5608">http://hdl.handle.net/10523/5608</a> OURArchvive access level Open Access Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Alpine Fault Zone Thesis description Number of pages, maps, CDs, etc. 249 pages A4 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Identifier An unambiguous reference to the resource within a given context 2015Cross Creator An entity primarily responsible for making the resource Cross, Andrew James Date A point or period of time associated with an event in the lifecycle of the resource 2015 Title A name given to the resource Microstructural evolution under non-steady state deformation in mid-crustal ductile shear zones Subject The topic of the resource Structural Geology Microstructure Alpine CPO deformation dynamic EBSD Evolution Fault grain growth microstructural quartz recrystallisation zone https://theses.otagogeology.org.nz/files/original/f6d90d51663a5b4305103648a4dbaf2f.pdf 1e396a41743c7317b70c8a2de7e15562 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Author last name Last name of the Author Loch Santos da silva Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student Fordyce, R.E. Kieser, J.A. Abstract The Abstract for this thesis Cetaceans are unusual mammals that have modified their morphological, physiological and behavioural systems to an aquatic existence. Access to new food sources and ecological niches may have been the trigger for this transition. The skull and feeding apparatus underwent drastic changes from the typical mammalian bauplan. Odontocetes show marked craniofacial changes associated with the ability to echolocate together with the development of elongated rostra and jaws bearing a large, yet simplified dentition. The teeth of odontocete s are peculiar when compared to most mammals, as monophyodonty, homodonty and polydonty are the trend for the group. Teeth have long been used to elucidate aspects of the ecology, functional morphology and systematics of fossil and recent mammal species. The aim of this research was to investigate the morphology, structure and biomechanics of odontocete teeth, in an effort to explore the functional implications and the evolution of the cetacean feeding apparatus. The multidisciplinary approach used here involved morphological description and basic morphometric measurements, as well as more refined techniques such as scanning electron microscopy, nanoindentation testing, geochemical analyses and micro-CT. The focus was in the Delphinida and Platanistoidea, to characterize a formerly speciose clade (Platanistoidea) versus an extant diverse clade (Delphinida). Some archaeocetes and early odontocetes were also analyzed. Results show that there was a high degree of morphological experimentation during the evolution of cetaceans, presumably to explore diverse niches and food sources. A more plastic configuration of the feeding apparatus in delphinoids may have been among the key aspects for the present diversity of the group when compared to a more fixed and conserved morphology in platanistoids and relict extant inioids. The morphological adaptation to an aquatic lifestyle was also reflected in the ultrastructure and mechanical properties of dental tissues in odontocetes. In early cetaceans, enamel was more complex and organized in Hunter-Schreger bands, which suggested a biomechanical adaptation related to food processing. Conversely, most living delphinoids showed a simpler radial or even prismless enamel structure. The lack of occlusion and food processing in most extant Delphinida was also reflected in the hardness and elastic modulus values for dolphin enamel and dentine, which were relatively lower than other mammals. Chemical analyses of odontocete enamel and dentine revealed a conserved tooth chemistry as in many other mammals, with calcium and phosphate being the main components, and minor elements such as magnesium, chlorine, sodium and fluoride. Chemical differences between enamel and dentine evoked different proportions of mineral versus organic content. While Microcomputed tomography was demonstrably useful as a non-destructive method for morphological analysis of extant teeth, it was less so in fossil teeth due to diagenetic alteration. Finally, massive levels of dental erosion, a process resulting in loss of enamel and dentine caused by acid demineralization, was reported and described for some extant delphinids. The multidisciplinary approach of this research allowed a broader characterization of the evolutionary changes and constraints in the structure of the teeth and feeding apparatus of odontocetes, contributing to the understanding of their functional morphology, general biology and evolution. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/4269">http://hdl.handle.net/10523/4269</a> OURArchvive access level Abstract Only Department The department where the student is studying primarily. Geology Thesis description Number of pages, maps, CDs, etc. 216 pages Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Identifier An unambiguous reference to the resource within a given context 2013Loch_Santos_da_silva Creator An entity primarily responsible for making the resource Loch Santos da silva, Carolina Date A point or period of time associated with an event in the lifecycle of the resource 2013 Title A name given to the resource Morphology, structure and evolution of teeth in fossil and modern odontocetes (Cetacea) Subject The topic of the resource Paleontology Cetacea Dolphins Evolution geochemistry Teeth Ultrastructure