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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.
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Showing 101 to 110 of 110 (0.045 seconds)| 101 |
Late Devonian (Famennian) brachiopods of the West Range Limestone and the Pilot Shale of Eastern NevadaMayer, Paul S. 30 August 1994 (has links)
Graduation date: 1995
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Macro- and microfossils from the Upper Cretaceous sedimentary rocks of Hornby Island, British Columbia, CanadaMcLachlan, Sandy Melvin Stuart 22 August 2017 (has links)
Heteromorph ammonites and dinoflagellate cysts from the Upper Cretaceous Northumberland Formation on Hornby Island, British Columbia, Canada are examined. The collection and preparation of new material has enabled the recognition of eleven species of which only three have been reported from the locality. Of these taxa represented from three heteromorph ammonite families in the study area, five are new occurrences and three are new to science. This expansion of the Hornby Island ammonite fauna is presented alongside a pioneering taxonomic survey of dinoflagellate cysts from the same rocks. Together, these macro- and microfossils reinforce a late Campanian age for the Northumberland Formation with the upper extent of the section approaching the Campanian-Maastrichtian boundary (CMB) interval. The palaeoecology
and evolutionary relationships of these heteromorph ammonoids are considered with new insights into their ontogenetic development and neritic palaeoenvironmental circumstances. The dinoflagellate cysts and associated terrestrial palynomorphs have also allowed for enhanced palaeoenvironmental reconstruction and depositional setting inference. The scope of the studied material, and the presence of key index taxa, enables refined biostratigraphy and a stronger basis for correlation of the Hornby Island succession with neighboring coeval biotic provinces. / Graduate / 2018-08-10
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Micropaleontology and Isotope Stratigraphy of the Upper Aptian to Lower Cenomanian (~114-98 Ma) In ODP Site 763, Exmouth Plateau, NW AustraliaAlibrahim, Ali 13 July 2016 (has links)
The biostratigraphy and isotope stratigraphy of the upper Aptian to lower Cenomanian interval including oceanic anoxic events OAE1b, 1c and 1d are investigated in ODP Site 763, drilled on the Exmouth Plateau offshore northwest Australia. Benthic foraminifera suggest that Site 763 was situated in outer neritic to upper bathyal water depths (~150-600 m). OAEs of the Atlantic basin and Tethys are typically associated with organic carbon-rich black shales and δ13C excursions. However, OAEs at this high latitude site correlate with ocean acidification and/or pyrite formation under anoxic conditions rather than black shales. Ocean acidification maybe responsible for sporadic low abundances of planktic foraminifera compared to radiolarians and benthic foraminifera associated with increased volcanogenic CO2 production during the formation of the Southern and Central Kerguelen Plateaus. Sea surface temperature may have cooled to 11°C in the late Aptian but increased gradually during the Albian. The Aptian/Albian boundary is placed at a negative carbon isotope excursion associated with the lowest occurrence of Microhedbergella renilaevis, typically found within the Niveau Kilian black shale of OAE1b. Third-order sea level cycles, particularly in the middle Albian, produced cyclic changes in the abundance of inoceramid prisms that increased during inferred times of falling sea level. The late Albian OAE1c and OAE1d coincide with horizons of intense pyritization and the absence of all biocomponents suggesting the development of euxinia. Warm Tethyan waters reached the Exmouth Plateau during the latest Albian based on the presence of thermocline dwelling keeled planktic foraminifera including Planomalina buxtorfi.
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A Tale of Two Species: Black-tailed and White-tailed Prairie Dog Biogeography from the Last Interglacial to 2070Bledsoe, April Dawn 01 May 2020 (has links)
Ecological niche models (ENMs) were created for White-tailed and Black-tailed prairie dogs and projected into the Last Interglacial (LI), the Last Glacial Maximum (LGM), and mid-Holocene (mid-H) to discern possible past suitable habitat for both species. Additionally, ENMs were projected into the future year 2070 representative concentration pathways (RCPs) 2.6 and 8.5 to discern how climate change may affect future habitat suitability. Kernel density estimations, minimum convex polygons, and median distribution centers of White-tailed and Black-tailed occurrence records were examined between time-periods to discern the effects of anthropogenic westward expansion on both species’ distributions. Current ENMs were constructed from commonly used bioclimatic variables and non-traditional variables (including EPA level III Ecoregions) for White-tailed and Black-tailed prairie dogs for variable comparison performance in ENMs. Results indicate that both species respond to climate change and each occupy distinct ecological niches. Biogeographical changes coincident with westward expansion remain unknown.
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The Hydrostatics and Hydrodynamics of Prominent Heteromorph Ammonoid Morphotypes and the Functional Morphology of Ammonitic SeptaPeterman, David Joseph 21 May 2020 (has links)
No description available.
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Neogene Palynology of the Gray Fossil Site, Tennessee, USA: Floristic Implications.Ochoa-Lozano, Diana 01 August 2011 (has links) (PDF)
In order to understand Mio-Pliocene floristic characteristics of the southern Appalachian Mountains, 47 palynological samples from six different testing-pits across the Gray Fossil Site (GFS) were analyzed. The site exhibits a low pollen yield resulting from basic pH levels, drought, and fire events occurring during deposition. The palynofloral assemblage has a low to moderate diversity, and it is largely dominated by Quercus-Carya-Pinus (~90% of the palynoflora). The reported presence of Pterocarya grains supports a Late Neogene age for the lacustrine sediments. Comparison with modern pollen-based floras suggests that: (1) the Mio-Pliocene Oak-Hickory-Pine association varied in structure between a woodland to woodland/savanna, depending on the intensity and frequency of drought, fire events and herbivory, (2) pits show different structure of the co-dominant genera, which indicate alternating composition of the vegetation, and (3) in term of modern vegetation, the GFS flora corresponds well with the Mesophytic Forest region.
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Phylogeny, Diversification, and Extinction Selectivity in Camerate CrinoidsCole, Selina R. 10 August 2017 (has links)
No description available.
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An Analysis of the Morrison Formation’s Terrestrial Faunal Diversity Across Disparate Environments of Deposition, Including the Aaron Scott Site Dinosaur Quarry in Central UtahEsker, Donald Anton 16 April 2009 (has links)
No description available.
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A historical perspective on recent landscape transformation: integrating palaeoecological, documentary and contemporary evidence for former vegetation patterns and dynamics in the Fleurieu Peninsula, South AustraliaBickford, Sophia Anastasia. January 2001 (has links) (PDF)
Includes bibliographical references (p. 301-319). Palaeoecological records, documented historical records and remnant vegetation were investigated in order to construct a multi-scaled history of vegetation pattern and change in the Fleurieu Peninsula, South Australia over the last c. 8000 years. Aims to better understand post-European landscape transformation and address the inherently historical components of the problems of regional biodiversity loss, land sustainability and the cumulative contribution to global climatic change.
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A historical perspective on recent landscape transformation: integrating palaeoecological, documentary and contemporary evidence for former vegetation patterns and dynamics in the Fleurieu Peninsula, South Australia / Sophia Anastasia Bickford.Bickford, Sophia Anastasia January 2001 (has links)
Includes bibliographical references (p. 301-319). / xx, 319, [30] leaves : ill. (some col.), maps ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Palaeoecological records, documented historical records and remnant vegetation were investigated in order to construct a multi-scaled history of vegetation pattern and change in the Fleurieu Peninsula, South Australia over the last c. 8000 years. Aims to better understand post-European landscape transformation and address the inherently historical components of the problems of regional biodiversity loss, land sustainability and the cumulative contribution to global climatic change. / Thesis (Ph.D.)--University of Adelaide, Dept. of Geographical and Environmental Studies, 2001
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