Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 20 for “"tetrapod"”.
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Hair Bundles of a Jawless Vertebrate Employ Tetrapod-Like Tuned Mechanical Amplification
<p>In the hearing and balance organs of tetrapod vertebrates, mechanical signals are transduced by an elegant organelle called the hair bundle. Deflections of this structure apply forces to mechanically gated ion channels. Hair bundles are not passive receivers of stimuli, but are instead active …
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Tetrapod phylogeny as inferred from 18S and 28S ribosomal-RNA sequence comparisons
The superclass Tetrapoda consists of several well defined monophyletic taxa: Anura, Urodela, Gymnophiona, Testudinata, Squamata, Rhychocephalia, Crocodilia, Aves and Mammalia. The relationships among these groups, however, is controversial. Neither paleontological evidence nor morphological, …
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Breakwater Enhancement: Redesign Tetrapod Structures for Resilient Coastal Environments and Marine Ecosystem Rehabilitation
… innovative and sustainable solutions. Tetrapod structures, while effective in coastal defense, suffer from their drawbacks, including substantial carbon emissions from concrete usage, limited mobility and deployability due to their massiveness, scalability challenges in fabrication, and …
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The Effects Of Vertebral Morphology And Composition On Stem-Tetrapod Intervertebral Joint Functional Behavior
… years, these terrestrial vertebrates (i.e., tetrapods) would diversify into profoundly different habitats and even re-invade aquatic environments. Among the changes associated with the water-to-land transition was the evolution of multipartite and complex vertebral forms, only one of which …
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Human networks of tetrapod translocations in the Western Cape, South Africa: trends and potential impacts on biodiversity
Global trends show an increase in wildlife trade associated with the process of globalisation and increased international trade. In addition, biodiversity managers are increasingly turning to species translocations to achieve conservation goals. These human induced movements of wildlife have a …
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Ichnology and sedimentology of large tetrapod burrows in the latest Early Triassic Katberg Formation, south-eastern main Karoo Basin, South Africa
Trace fossils in the form of large (~11 cm diameter and up to 2 m in length) burrows were studied at three localities in the Early Triassic Katberg Formation in the south-eastern and central parts of the main Karoo Basin, Eastern Cape, South Africa. The most interesting site, Hobbs Hill, northwest …
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A Community-Scale Perspective on the Diversification of Tetrapod Ecology and Botanical Turnover based on the Pennsylvanian of the Maritimes Basin, Atlantic Canada
… Ma), as the ecological roles of terrestrial tetrapods rapidly diversified. At a global scale, the expansion of tetrapod ecology occurred roughly in concert with major disruption in plant community composition, leading some to propose a causal link between the two phenomena. My dissertation …
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Rise of present-day tetrapods in the paleotropics of Late Triassic equatorial Pangaea: new insights from microvertebrate data
… radiation and reorganization of continental tetrapod diversity following the end-Permian Extinction, including an assemblage of diverse forms that do not survive the end-Triassic (herein termed the 'endemic Triassic fauna', =ETF), as well as the earliest fossil representatives of all major …
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A Comparison of Limb Development of the Salamanders Plethodon Cinereus and Ambystoma Mexicanum
Tetrapod limbs exhibit a wide variety of developmental variation. Amphibians alone display a fair amount this variation. Here, the development of both limb pairs in the species Plethodon cinereus and Ambystoma mexicanum are compared. Using histology and microCT on embryonic and juvenile specimens, …
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Differential gene expression analysis reveals functional roles of cryptic orange-pigmented organ in the colorless head kidney of Antarctic icefishes
… tissue cells – the teleost homolog of the tetrapod adrenal cortex but are normally dispersed among the teleost head kidney tissue. Transcription of many cytochrome P450 enzymes participating in steroidogenesis were upregulated, potentially leading to greater levels of ROS and peroxidation …
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The Pareiasaur Elginia from Elgin, north east Scotland, and the late Permian extinction event
… of marine invertebrates and non-marine tetrapods is examined. Fauna!, lithostratigraphical and geochemical data indicate that the mass extinction was a prolonged, gradual event, and was not initiated or accelerated by a catastrophic mechanism. The cause of the greatest ever reduction in …
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Investigating the Patterns of Convergence in Pectoral Girdle Reduction During the Evolution of Limblessness in Lerista (Scincidae)
Over 30 tetrapod groups have evolved a snake-like, elongate, limbless body plan. Studies of the patterns of limb reduction have revealed a close relationship between the reduction of the limbs and body elongation; however, the loss of the skeletal elements that support the limb, the pectoral …
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Complex evolution of mitochondrial genomes: lessons from salamanders
… have the lowest metabolic requirements among tetrapods, experience weaker purifying selection on protein-coding sequences than do frogs, a comparable amphibian clade with higher metabolic rates. In contrast, there is no evidence for weaker selection against mitochondrial genome expansion in …
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The influence of developmental patterns on vertebrate evolution, with the evolution of the sacrum and pelvis as a case study
… time. The pelvic complex plays a central role in tetrapod locomotion with the exception of taxa lacking hindlimbs (e.g., whales, snakes, caecilians). This complex, composed of the pelvic girdle (ilia, ischia, and pubes) and the sacrum (vertebrae articulated with the ilia via sacral ribs) is in …
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The role of MK2/TTP pathway in regulating early development and innate immunity in zebrafish
… requirement for MK2 arose after the division of tetrapod and teleost lineages. The role of mk2a and its gene duplicate mk2b in regulating immune response has not been previously studied in zebrafish. I developed zebrafish as a model infection system for infection by multiple species of Candida, …
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CHARACTERIZATION OF THE EUKARYOTIC TRANSLATION INITIATION FACTOR 4E (eIF4E) FAMILY MEMBERS IN THE ZEBRAFISH (Danio rerio)
… of mRNA recruitment. It has been retained in tetrapods, but lost in higher teleosts. eIF4E-1C, appears to have retained function as a prototypical initiation factor. A duplication of Class II eIF4Es occurred prior to the emergence of the tetrapod branch, becoming eIF4E-2A and -2B. The genes …
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Evaluation of tridactyl theropod tracks in southern Africa: quantitative morphometric analysis across the Triassic–Jurassic boundary
… Group) of main Karoo Basin, host a diverse tetrapod osteological and ichnite record. Due to an absence of high resolution radioisotopic age determinations, the exact stratigraphic placement of the TJB remains unknown. Although diverse ichnofossils attributed to Saurischians and …
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Assessing sources of variation in amphibian skin thickness: ecological and evolutionary implications
… of the body and provides many functions. Among tetrapod vertebrates, amphibian skin is semi-permeable and responsible for a greater proportion of water absorption and gas exchange. Myriad factors affect the physiological performance of amphibian skin. Morphological traits linked with amphibian …
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The development and evolution of vertebrate oxygen-sensing cells
… (ray-finned bony fish) and frog (anamniote tetrapod) are not neural crest-derived, and hence are not homologous to carotid body glomus cells. Genetic lineage-tracing in mouse and neural fold grafts in chick also confirmed that serotonin-positive neuroendocrine cells in the lung are not …
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Electrostatically-driven self-assembly of polyelectrolytes and colloidal tetrapods
… second theme is the self-assembly of colloidal tetrapods using Monte Carlo simulation. The third theme is the new techniques that needed to be devised in order to perform this work. Chapter 2 presents an extensive exploration of the free-energy landscapes governing the interaction between two …