Dissertations / Theses: 'Fossil bone'

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Turner-Walker, Gordon Howard. "The characterisation of fossil bone." Thesis, Durham University, 1993. http://etheses.dur.ac.uk/5700/.

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This research presents a multi-disciplinary approach to the analysis of ancient bones, in which many different chemical and physical analytical techniques were applied to a relatively small sample of human and animal bones from different depositional environments. The results of these analyses indicate that the principle mechanisms responsible for diagenetic alteration of buried bones are chemical hydrolysis of bone collagen and microscopic tunnelling by saprophytic micro-organisms. These mechanisms, either independently or together, result in an increase in the porosity of the bone at a microscopic scale from a value of approximately 20 percent in fresh bone up to as much as 65 percent in some archaeological bones. There is no evidence that the hydrolysis of collagen in buried bones directly affects the mineral component of bone, although the breaking of the intimate association between the collagen molecules and the bone apatite crystallites exposes the crystallites to potential dissolution and recrystallization by percolating ground water. Disruption of the collagen-apatite bond has been recognised in optical microscopy of thin sections by loss of the characteristic birefringence seen in unaltered bone when viewed in polarised light. The birefringence in histologically normal bone results from the strongly anisotropic orientation of the bone mineral crystallites imposed by their association with the highly organised collagen fibrils. Loss of birefringence as a result of diagenetic activity is attributed to a randomising of the orientation of crystallites after hydrolytic degradation of the collagen molecule. With progressive loss of collagen the relative calcium and phosphorus contents of fossil bones have been found to increase in proportions close to those of stoichiometrically correct hydroxyapatite. Microscopic and mineralogical studies have suggested that changes in the crystallinity of buried bones may be attributed to the presence of well-ordered crystals of hydroxyapatite in the pore structures of the bones and that these derive from dissolution and re-precipitation of the original bone apatite. However the elemental and isotopic composition of these re-precipitated apatites may not reflect that of the original bio mineral due to the incorporation of strontium, uranium fluoride etc. from the environment. Dissolution of bone mineral can, in most cases, be associated with the action of micro-organisms, many of which are known to favour low pHs and secrete organic acids as a by-product of their metabolism. Although micro-organisms isolated from buried bones produce collagen degrading enzymes (collagenases) these enzymes are too large to enter the spaces between the bone apatite crystallites and are therefore unable to attack the collagenous matrix of undegraded bone. Before micro-organisms can utilise bone collagen, the bone matrix must first be demineralized to expose the collagen fibrils or the collagen must be degraded by hydrolysis into shorter lengths that then escape via disrupted regions of the surrounding crystallites. Analysis of the strengths of modem and fossil bones has demonstrated a near logarithmic relationship between tensile strength and porosity. In addition, plots of strength vs porosity and strength vs nitrogen content are bimodal, indicating that two mechanisms are involved in the degradation of fossil bones. The microscopic and chemical analyses suggest that these mechanisms are chain scissioning of collagen and tunnelling by micro-organisms. Microscopic studies show that surface adsorption of 'humic acids' and metal ions are responsible for the colouration of fossil bones. Analysis of the total lipid extract of fossil bones contain cholesterol and cholesterol degradation products. Fossil cholesterol represents a potentially important and unique resource for palaeodietary studies. Conversely, this research has demonstrated that studies of ancient DNA are compounded by inhibition by compounds from the soil and contamination by modem DNA. Fossil bones in anoxic or wateriogged soils are readily colonised by sulphate-reducing bacteria and these bacteria are responsible for the deposition of iron sulphide in the form of pyrite framboids in pore spaces in the bone. On exposure to atmospheric oxygen, these pyrite framboids oxidise to sulphuric acid which in turn attacks bone apatite, resulting in the formation of vivianite (Fe(_3)(PO(_4))(_2).8H(_2)O) and gypsum (CaSO(_4).2H(_2)O). Crystallization and hydration of these minerals frequently disrupt the physical integrity of the bone specimens. Finally this research indicates potential regimes for the conservation of fossil bone specimens together with the archaeological or environmental evidence preserved within them.

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Murer, Fredrik Kristoffer. "X-ray Diffraction Computed Tomography of a Fossil Bone Sample." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23618.

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A fossil bone sample, a humerus (”upper arm”) of a prehistoric fish, Eusthenopteron Foordi, has been studied using a combination of X-ray diffraction, computed tomography and synchrotron radiation. The technique has in this thesis been called X-ray diffraction computed tomography. It has been attempted to obtain three-dimensional tomographic images of sample regions containing different minerals, as well as to determine crystallite orientation properties of the different minerals.The sample has been found to consist of hydroxylapatite, barite, calcite, quartz and pyrite. Three-dimensional tomographic images of the four first minerals have been made using the filtered backprojection algorithm. Image artifacts were reduced by combining recorded intensity from several Bragg peaks and by combining data from two separate tomographic measurements of the sample.A fraction of the hydroxylapatite crystallites appear to have a preferredorientation. The direction of this preferred orientation has been deter-mined for some regions close to the sample edge.

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Quam, Rolf Michael. "Temporal bone anatomy and the evolution of acoustic capacities in fossil humans." Diss., Online access via UMI:, 2006.

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Marín, Moratalla Miren Nekane. "Reconstructing life history traits from bone histology in extant and fossil ruminants." Doctoral thesis, Universitat Autònoma de Barcelona, 2014. http://hdl.handle.net/10803/285623.

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El estudio de las life histories es de vital importancia porque proporciona evidencias sobre las condiciones ecológicas, biodiversidad, demografía, vulnerabilidad y otros muchos aspectos de la biología de las especies. La histología ósea es utilizada como herramienta para reconstruir las life histories de vertebrados, analizando el tejido óseo primario o contando el número de marcas de crecimiento (esqueletocronología). Sin embargo, se ha considerado que los endotermos, al contrario que en ectotermos, muestran un crecimiento óseo no cíclico, invalidando la histología ósea para inferir las life histories de mamíferos. El objetivo general de esta tesis es proporcionar las bases de la histología ósea en mamíferos para inferir estrategias de life history. Los objetivos concretos son: i) analizar la fiabilidad de la esqueletocronología ósea en mamíferos, ii) explorar la asociación entre las características del tejido óseo y el ambiente, fisiología, ontogenia y life history y, iii) reconstruir las características de life history en mamíferos fósiles y actuales para obtener datos sobre la evolución de las life histories y biología de la conservación. Se han analizado 274 láminas transversales de hueso de 225 individuos pertenecientes a lirones actuales (Gliridae) y rumiantes actuales y fósiles (Bovidae, Cervidae, Moschidae y Tragulidae). Se han llevado a cabo tanto análisis cualitativos como cuantitativos. Los análisis cualitativos el tejido óseo primario muestran que, en los estadios tempranos de la ontogenia, los rumiantes forman un tejido fibrolamellar (FLC), mientras que los lirones depositan generalmente un tejido parallel fibered bone (PFB). Cuando son adultos, tanto lirones como rumiantes depositan un hueso lamelar denso (External Fundamental System, EFS). Los resultados también muestran que los Lines of Arrested Growth (LAGs) están presentes de forma universal en los mamíferos analizados. Los LAGs están presentes tanto en el tejido de formación rápido (FLC) así como el tejido de formación lento (EFS). El número de líneas de crecimiento en el hueso concuerda con la edad de los animales, proporcionando la evidencia de la periodicidad anual de los LAGs en estos mamíferos. El fémur es el hueso más conservador para aplicar la esqueletocronología ya que registra el mayor número de LAGs. La remodelación y reabsorción ósea puede eliminar o enmascarar los primeros LAGs depositados durante la ontogenia. Esta investigación muestra que el crecimiento óseo se detiene durante el periodo adverso (pocos recursos), acoplado con la variación fisiológica estacional. Estos resultados apoyan que la parada de crecimiento forma parte de una estrategia termometabólica de conservación energética. Además, este trabajo muestra que las características vasculares y celulares del tejido óseo primario sufre una importante variación ontogenética asociada al descenso de la tasa de crecimiento al acercarse la madurez. La densidad vascular y celular decrece mientras que la proporción de canales longitudinales en relación a los circulares incrementa a lo largo de la ontogenia hasta alcanzar la madurez, lo cual podría estar relacionado con la madurez fisiológica. El cambio más significativo durante la ontogenia ocurre durante la transición entre el FLC o PFB a EFS, lo cual está relacionado con la madurez reproductiva. Este trabajo evidencia que esta transición registra el trade-off entre crecimiento y reproducción en rumiantes. De acuerdo con estos hallazgos, la edad de madurez reproductiva puede determinarse contando el número de ciclos de crecimiento antes del EFS. Los resultados comparando las características histológicas cuantitativas entre bóvidos sugiere que los parámetros vasculares y celulares están relacionados con la masa corporal y el metabolismo. De esta forma, el hueso FLC de grandes bóvidos tiende a mostrar más canales circulares (lo cual estaría reflejando mayores tasas de deposición de hueso perióstico) y menores densidades celulares (lo cual estaría reflejando una menor tasa metabólica específica de masa) que los pequeños.
Bone histology is a widely used tool to reconstruct vertebrate life histories, either by analysing primary bone tissue or by counting the number of growth marks (skeletochronology). However, it has long been considered that endotherms, unlike ectotherms, display a continuous or noncyclical bone growth, disabling bone histology for life history inferences in mammals. The general purpose of the research presented in this PhD Thesis is to challenge this statement, contributing to the foundations of mammalian bone histology as a tool for inferences on life history strategies. A sample of 274 bone cross-sections from 225 individuals belonging to extant dormice (Gliridae) and extant and fossil ruminants (Bovidae, Cervidae, Moschidae and Tragulidae) have been analysed under polarized and transmitted light microscopy. The results show that Lines of Arrested Growth (LAGs) are universally present in both mammalian groups analysed in this work. These growth marks are present throughout both, the fast-growing bone tissue deposited during growing period (fibrolamellar bone, FLC or parallel fibered bone, PFB) as well as the slow-growing dense lamellar tissue deposited during the adulthood (External Fundamental System, EFS). The number of rest lines in cortical bones fits well with chronological age of the animals, providing evidence of the annual periodicity of bone growth marks in these mammals. The femur is clearly the most reliable bone for skeletochronology analyses because it records the greatest number of LAGs. Despite this, bone remodelling and resorption can potentially delete or obscure the earliest ontogenetic record, especially in large ruminants. This research further indicates that bone growth is arrested during the energetically challenging period (low resource supply), coupled with physiological seasonal variation. These findings provide support that growth arrest forms part of a thermometabolic strategy for energy conservation. Moreover, this work shows that vascular and cellular features of primary bone tissue undergo strong ontogenetic variation associated with a decrease on growth rate as maturity approaches in mammals. Specifically, vascular and cellular densities decrease whereas the proportion of longitudinal canals in relation to circular ones increases throughout ontogeny until reach maturity, which may be related to physiological maturity. However, the most significant change along ontogeny occurs during the transition between the main primary tissues, from FLC/PFB to EFS, which is related to reproductive maturity. This work provides evidence that this transition reliable records the trade-off between growth and reproduction in ruminants. According to these findings, the age at reproductive maturity can be determined by counting the number of growth cycles within the fast growing tissue before the EFS. The result of comparing histological quantitative features between bovids suggests that vascular and cellular parameters are related to body mass and metabolism rather than to extrinsic factors, such as climate. Accordingly, the FLC bone of larger bovids tends to show more circular canals canals (which may reflect higher rates of periosteal bone deposition) and lower cellular densities (which may reflect lower mass-specific metabolic rate according to Kleiber’s law) than the smaller ones. Finally, the findings on fossil species provide evidence that bone histology is a valuable tool to explore evolutionary trends in mammalian life histories. Moreover, the results of bone histology to get some life history traits in endangered mammals highlight its usefulness on the field of conservation biology. To conclude, the findings of this work provide evidence that, in mammals, bone growth is mainly regulated by endogenous rates and synchronized with seasonal resource availability. The evidence of cyclical bone growth debunks the classical assumption that homeothermic endotherms grow continuously until they attain maturity, providing a clear support to the usefulness of bone histology to reconstruct life history traits in extinct and extant mammals.

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Fortier-Dubois, Étienne. "Late Devonian vertebrates from Siberia: a synchrotron microtomography study of bone bed material." Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-281633.

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This is an investigation of new vertebrate fossil material from the Late Devonian locality of Ivanovka, Uryup River, Siberia. This bone bed material, circa 375 million years in age, represents a unique opportunity to fill a gap in our understanding of Late Devonian diversity, biogeography, and vertebrate evolution: Siberia, at the time, was an independent continent, and yet its fauna remains virtually unknown in comparison with the other paleocontinents, Euramerica and Gondwana. Using synchrotron microtomographic scanning, a non-destructive technique that has never, to our knowledge, been applied to bone bed material, we obtained 3D image stacks that were then modelled to yield triangle meshes representing the bones in three dimensions. These meshes could then be identified, described, and interpreted. Many of the discovered bones belong to the poorly known genus Megistolepis Obruchev 1955, potentially allowing a radical increase in knowledge regarding this taxon. Other material includes lungfish and possible fragments of limbed tetrapods, though the evidence of the latter is scarce. A discussion of the advantages and disadvantages of synchrotron microtomography for the study of bone bed material concludes the paper.

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Klinken, G. J. van. "Dating and dietary reconstruction by isotopic analysis of amino acids in fossil bone collagen-with special reference to the Caribbean." Amsterdam : Fondation for Scientific Research in the Caribbean Region, 1991. http://catalog.hathitrust.org/api/volumes/oclc/26955816.html.

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Holland, Andrew D. "Examining the taphonomic challenges to the 3D digitisation of fragmented bone." Thesis, University of Bradford, 2017. http://hdl.handle.net/10454/15180.

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The utilisation of 3D digitisation and visualisation has grown considerably since 2008 and is becoming an increasingly useful tool for the digital documentation and metric analysis of archaeological artefacts and skeletal remains. It provides public access to rare and fragile specimens of palaeontological and palaeopathological importance whilst reducing the physical impact on these remains. Research in engineering and computer vision provides some insight into the impact of surface properties such as colour, specularity, reflectance and shape on the quality of the recorded 3D image, but within the archaeological and palaeontological disciplines comparable work has not yet been developed. If archaeology and anthropology are to provide long term reliable data from archaeological and palaeontological specimens in a way that doesn’t require repeated re-digitisation, we need to understand the impacts that the taphonomic histories of such samples have on our ability to 3D record them. Understanding the relationship of these taphonomic histories and the surface and optical properties will promote informed choices about the suitability of recording techniques. This thesis considers the taphonomic processes that affect the preservation of bone over archaeological, forensic and palaeontological timescales and the effect this has on the quality of 3D digital models. The digital refit of fragmentary bone samples is considered in relation to the effect of taphonomic alterations to bone. Conclusions regarding the key taphonomic factors and 3D digital model quality are drawn and areas of further work are identified.

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Bulygina, E. "A comparative study of frontal bone morphology of Late Pleistocene fossil hominins from the territory of the former Soviet Union." Thesis, University College London (University of London), 2007. http://discovery.ucl.ac.uk/1444562/.

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The major aim of the present work is to provide a re-assessment of the morphological and taxonomic affinities of several adult and juvenile fossils from the territory of the former Soviet Union that retain frontal bones. Nine fossils were analysed and compared with a sample of Late Pleistocene hominins and recent modern populations. Analytical techniques included traditional inter-landmark measurements, as well as a geometric morphometric toolkit for the 3D surfaces. The following patterns were found in the comparative sample: 1) the best differentiation in the frontal bone morphology exists between the 'modern' and 'archaic' groups of hominins, where the former is composed of recent and Upper Palaeolithic modem humans, and the latter incorporates Neanderthals and early modern humans from Africa and West Asia 2) Upper Palaeolithic humans from central and eastern Europe differ significantly from the pooled sample of the nine recent modern human populations 3) the morphology of the complete frontal bone discriminates between hominin groups better than the supraorbital relief 4) recent modern humans and Neanderthals display diverging growth trajectories in the shape of the frontal bone differences already exist at the earliest age stages represented here (2.5 years in Neanderthals) and increase towards adulthood. Within the above framework, all Sungir' fossils align with the recent modern human morphological variation. In contrast, the fossil frontal from Podkumok, North Caucasus, is associated with the Upper Palaeolithic sample of fossils. Satanay, Khvalynsk and Skhodnya frontal bones have an ambiguous morphological associations generally aligning with the modem morphology but demonstrating particular combination of features that sometimes make them closer to the 'archaic' fossils in the sample. The Teshik-Tash child is found to be similar to Neanderthals in the frontal bone morphology. However, it shows lesser degree of the development of the 'classical' Neanderthal morphology and deviates towards the early modern humans. The Starosel'e child did not demonstrate any affiliation with the 'archaic' morphological pattern in its frontal bone.

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Gerwitz, Andrew. "Evaluating potential growth strategies using bone histology in Pleistocene-Holocene Odocoileus virginianus (Mammalia) from Florida." Kent State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=kent1470322817.

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Iliopoulos, George. "The Giraffidae (Mammalia, Artiodactyla) and the study of the histology and chemistry of fossil mammal bone from the Late Miocene of Kerassia (Euboea Island, Greece)." Thesis, University of Leicester, 2003. http://hdl.handle.net/2381/35044.

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A taphonomic investigation of Late Miocene mammal bones and teeth and a taxonomic study of the abundant and diverse giraffid material from Kerassia, Greece, were undertaken. The material was collected from seven different sites near Kerassia, where at least two fossiliferous horizons occur. Microbial action caused extensive destruction in almost all the examined specimens of bone and teeth tissues from both horizons. Despite this, and contrary to the established ideas, bioeroded tissues survived to become fossils, preserving their histological and bioerosion features. The diameters of the microtunnels (150-600 nm) in the destructive foci indicate that the invading microorganisms were bacteria. Recrystallization of the apatite crystallites in the foci of damaged tissues occurred immediately after the end of bacterial activity, restraining later diagenetic recrystallization. This process is responsible for differences in the chemistry of the three structural areas of the bioeroded tissues, the undamaged areas, the foci and the rims of the foci. X-ray diffraction mineralogical analyses showed that fossil bone and dentine consist of carbonate fluorapatite and enamel consists of carbonate hydroxyapatite. The crystallinity of the fossil tissues is not age dependent but rather reflects the type of the hard tissue and the conditions of the local burial environment. To date, five different species of giraffes have been determined in Kerassia. Four species were found in the lower horizon, Palaeotragus rouenii, Palaeotragus sp., Samotherium major and Helladotherium duvernoyi and four species were found in the upper horizon Palaeotragus rouenii, Samotherium major, Helladotherium duvernoyi and Bohlinia attica. Finally, this study shows that a seasonal Mediterranean type, relatively temperate to warm and moist climate, can be inferred for the MN12 (Middle Turolian) of the Kerassia region.

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南, 雅代, Masayo Minami, 俊夫中村, and Toshio Nakamura. "骨化石試料に対する信頼度の高い<14>^C年代, 炭素同位体比測定の試み." 名古屋大学年代測定資料研究センター天然放射性元素測定小委員会, 1997. http://hdl.handle.net/2237/13350.

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HIRATA, Kazuaki, Tomohito NAGAOKA, Toshio NAKAMURA, Masayo MINAMI, Ken SAKATA, 和明平田, 朋人長岡, 俊夫中村, 雅代南, and 健. 坂田. "アミノ酸組成ならびに14C年代に関する同一古人骨の部位による比較." 名古屋大学年代測定資料研究センター, 2012. http://hdl.handle.net/2237/18162.

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Dibenedetto, Joseph Nicholas. "Paleoclimatological implications of fossil tortoise bones." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2008. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.

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Aufort, Julie. "Fossilisation des apatites biologiques : approche cristallochimique et applications géochimiques." Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS484.

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Les fragments de squelettes de vertébrés préservés sous forme de fossiles fournissent des informations paléo-environnementales uniques via leur composition isotopique et leur teneur en éléments traces. Toutefois la validité de ces informations dépend crucialement de la préservation de l’enregistrement géochimique biogénique au cours de la fossilisation. Ce travail a pour objectif de comprendre comment s’effectue l’acquisition de l’information géochimique puis sa préservation en étudiant les propriétés de fractionnement isotopique de l’apatite, constituant inorganique majeur des os et dents de vertébrés, et les mécanismes de transformations cristallochimiques impliqués par la fossilisation. Celles-ci sont sondées à l’échelle atomique à l’aide des spectroscopies ATR-FTIR et RMN du solide, leur interprétation s’appuyant sur la modélisation des spectres ATR-FTIR et le calcul ab initio (DFT) des propriétés de fractionnement isotopique à l’équilibre de l’apatite. Les transformations à l’échelle atomique observées suite à l’altération d’os actuel en solution aqueuse attestent d’un processus de dissolution partielle de l’apatite biogénique et de formation de fluor- ou hydroxy- apatite carbonatée secondaire à la surface des cristallites, selon la présence ou non de fluor en solution. Ces résultats ont ensuite été appliqués à l’étude de la transformation d’os fossiles issus des environnements karstiques de Bolt’s Farm dans le Berceau de l’Humanité (Afrique du Sud) et des environnements fluvio-lacustres volcano-sédimentaires des collines Tugen dans la vallée du Rift Grégory (Kenya). La formation de fluorapatite carbonatée est systématiquement observée, de l’hydroxyapatite carbonatée est également formée dans les fossiles de Bolt’s Farm moins fluorés, soulignant ainsi le potentiel des ossements fossiles à révéler les conditions précoces de fossilisation. Un degré maximal de transformation, aussi bien des os fossiles que des os actuels altérés, est observé à environ 60 % d’apatite secondaire, suggérant l’idée d’un rôle protecteur de cette phase contre la dissolution totale de l’apatite primaire
Chemical and stable isotope compositions of fossil remains of vertebrates provide unique palaeo-environmental information. However, its reliability depends on the preservation of the biogenic geochemical record during the fossilisation process. This work aims to undersand how the geochemical record is acquired and preserved by studying the isotopic fractionation properties of apatite, the main inorganic constituent of vertebrates bones and teeth, and the crystal-chemical transformations occuring during fossilisation. These transformations are probed at the atomic scale using ATR-FTIR and solid-state NMR spectroscopies and their interpretation is supported by the modelling of ATR-FTIR spectra and DFT calculations of theoretical equilibrium isotopic fractionation properties. Atomic scale transformations of bones altered in aqueous solutions consist of partial dissolution of the biogenic apatite and formation of secondary carbonated fluor- or hydroxy- apatite, depending on the presence or absence of fluoride in the solution. These results were then applied to the study of the transformation of fossil bones from the karstic environments of Bolt’s Farm cave system (Cradle of Humankind, South Africa) and from the fluvio-lacustrine environments of the Tugen Hills (Gregory Rift, Kenya). Systematic formation of secondary carbonated fluorapatite is observed, as well as formation of secondary carbonated hydroxyapatite in the less fluorinated Bolt’s Farm fossils, highlighting the potentiality of fossil bones to record local physical-chemical conditions prevailing in fossilisation environments. The ~ 60 % maximum fraction of secondary apatite observed in fossils and modern bones altered under controlled conditions suggests it has a protective role against further dissolution of the primary apatite

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Brassey, Charlotte. "Biomechanical modelling of long bones and body mass estimation in modern and fossil species." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/biomechanical-modelling-of-long-bones-and-body-mass-estimation-in-modern-and-fossil-species(112da3ec-eb91-4d2e-bde1-64ed5d8b2299).html.

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The thesis presented herein utilizes a variety of methods to address the biomechanical function of vertebrate hind limb bones in both modern and fossil species. In an innovative application of beam theory, the maximum force a long bone is capable of withstanding before yield is calculated under a variety of simplified loading conditions for a phylogenetically diverse sample of modern birds and mammals. In doing so, new insights are gained into the combined role of limb bone geometry and load vector in achieving mass-invariant safety factors under static loading. In particular, the avian femur is found to scale with sufficient allometry such that no postural modification is required to maintain constant safety factors across several orders of magnitude in body mass. In a methodological study, two techniques for estimating stress (simple beam theory and finite element analysis, FEA) are compared across a sample of morphologically diverse long bones. The extent to which stress estimates derived from the two modelling techniques diverge is found to correlate to aspects of the underlying bone morphology such as shaft curvature and cross-sectional asymmetry, and important recommendations are made regarding the appropriate application of both methods to skeletal material. A novel ’convex hull’ volumetric mass prediction technique for fossil birds is applied to two species of extinct moa (Dinornithiformes) from New Zealand. The resulting mass estimates are incorporated into a FEA study of the femora and tibiotarsi of modern ratites and moa. The ’stout southern’ moa (Pachyornis australis) is confirmed as possessing extremely robust limbs, whilst the ’terrible robust’ moa (Dinornis robustus) is found to possess equally, if not less, robust limb bones than those of modern ratites. The results are subsequently interpreted in the context of moa habitat range and shared ancestry. Finally the convex hull mass estimation technique is extended to modern primates, and the scaling of body mass with convex hull volume is compared across birds, primates and non-primate mammals. The allometric scaling of convex hull volume in birds and primates is considered in light of interspecific variation in muscle volume, body fat and integumentary structures, and is particularly relevant to those reconstructing the soft-tissue architecture of fossil species.

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Giles, Sam. "How to build a bony vertebrate in evolutionary time." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:1df4ba59-c709-4e3c-99c0-b49d1132743f.

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Jawed vertebrates (gnathostomes) account for over 99% of living vertebrate diversity, with origins that stretch back nearly half a billion years, and comprise two groups: Osteichthyes (fishes and land-dwelling vertebrates) and Chondrichthyes (sharks, rays and chimaeras). Osteichthyans are the dominant clade, with at least 60,000 species approximately evenly divided between two clades: the Actinopterygii and the Sarcopterygii. However, our understanding of early osteichthyan evolution is skewed in favour of sarcopterygians, leaving the origin of nearly half of all vertebrate diversity critically understudied. Furthermore, recent upheavals in the early gnathostome tree have destabilised relationships amongst fossil taxa and eroded our understanding of primitive anatomical conditions of key groups. Central to understanding early gnathostome evolution is the braincase, an anatomically complex structure that provides a wealth of morphological characters. However, braincases rarely fossilise, and their position inside the skull makes them difficult to attain. X-ray tomography allows a comprehensive description of the internal and external anatomy of fossils, including the braincase. This thesis sets out to target phylogenetically pivotal taxa and incorporate new anatomical data in building up a picture of character evolution in early jawed vertebrates. In particular, I target the gnathostome stem, describing a new taxon that helps bridge the morphological gap between placoderms and crown gnathostomes, allowing a more comprehensive understanding of both dermal and endoskeletal evolution. I also focus on early actinopterygians, describing the endoskeleton of the first members of the group in order to understand primitive anatomical conditions. I then investigate actinopterygian braincase anatomy in the context of a revised phylogenetic analysis, illuminating the early evolution of the actinopterygians. Finally, I present a synthetic review of braincase anatomy across the early gnathostome tree. These results provide a more accurate picture of braincase evolution across gnathostomes and actinopterygians, clarifying our understanding of their evolution while revealing new information about when key innovations arose in the brains of the very first ray-finned fishes.

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Hieronymus, Tobin L. "Osteological Correlates of Cephalic Skin Structures in Amniota: Documenting the Evolution of Display and Feeding Structures with Fossil Data." Ohio : Ohio University, 2009. http://www.ohiolink.edu/etd/view.cgi?ohiou1237491191.

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Wong, Shu-hing Louise. "Replicating mesenchymal cells in the glenoid fossa in response to mandibular advancement." Click to view the E-thesis via HKUTO, 2002. http://sunzi.lib.hku.hk/hkuto/record/B31973140.

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黃淑興 and Shu-hing Louise Wong. "Replicating mesenchymal cells in the glenoid fossa in response to mandibular advancement." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31973140.

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Pereira, Marcos Alexandre da Franca. "Descompressão dos segmentos timpânico e labiríntico do nervo facial via fossa craniana média." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/5/5143/tde-02052016-090526/.

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Introdução: A paralisia facial periférica caracteriza-se pela interrupção, definitiva ou temporária, do funcionamento da musculatura facial. Decorre de lesão ou mau funcionamento das fibras do nervo facial. É uma enfermidade que causa enorme impacto estético e funcional. O topodiagnóstico e o tratamento da paralisia facial periférica pode requer abordagem médica e fonoaudiológica; ser exclusivamente medicamentoso ou associado à terapia de reabilitação, ou ainda, medicamentoso e cirúrgico, seguido da reabilitação da mímica facial. A via FCM tem sido usada para a descompressão do NF quando a audição precisa ser preservada. Esse acesso pode ser realizado de forma isolada, ou combinado à via transmastóidea. Objetivo: Descrever uma técnica inovadora para a descompressão do nervo facial via fossa craniana média que permite a exposição direta dos segmentos labiríntico e timpânico do nervo facial, com a preservação da função da orelha interna. Métodos: Vinte cabeças extraídas de cadáveres adultos de ambos os gêneros, sem sinais de malformação, traumatismo, doença ou manipulação cirúrgica prévia foram usados neste estudo. Os pontos de referência utilizados foram a artéria meníngea média, o nevo petroso superficial maior, a eminência arqueada, o seio petroso superior, e o plano meatal seguido no ápice petroso a partir da sua porção mais anterior e medial. Foi feita a dissecação do plano meatal, com visualização do meato acústico interno, seguido no ápice petroso a partir da sua porção mais anterior e medial até a região do gânglio geniculado. Foi aberto o tégmen timpânico e identificada a porção timpânica do nervo facial. A dissecação seguiu no sentido retrógrado da porção timpânica do nervo facial em direção ao gânglio geniculado, até a sua porção labiríntica. A aracnoide do meato acústico interno era aberta, e depois de identificado o nervo facial, a bainha deste nervo era aberta em extensão exposta. Resultados: As distâncias médias, entre o canal semicircular lateral e a porção média do cabo do martelo eram similares em ambos os lados (4,0mm±0,5mm). As distâncias médias, da porção timpânica do nervo facial até metade do cabo do martelo foram determinadas e resultaram em 2,0mm ± 0,44mm, e em 2,2mm ± 0,48mm para os lados direito e esquerdo, respectivamente. O segmento timpânico do nervo facial apresentou, em média, comprimento total de 11mm ± 0,67mm para o lado direito, e 11,5mm±0,60mm para o esquerdo. Os comprimentos longitudinais da janela óssea confeccionada no tégmen timpânico foram, em média, 16,8mm±1,67mm para o lado direito, e 16,8mm ± 1,20mm para o lado esquerdo. Já os comprimentos transversais da janela óssea confeccionada no tégmen timpânico foram, em média, 5,5mm ± 1,20mm e 5,0mm ± 1,75mm para os lados direito e esquerdo, respectivamente. O valor médio da área elíptica formada pelos comprimentos longitudinal e transversal da janela óssea confeccionada no tégmen timpânico foram 72,5mm2 ± 22,5mm2 à direita, e 65,9mm2 ± 30,3mm2 à esquerda. Conclusão: A técnica proposta pode ser utilizada para a cirurgia de descompressão do nervo facial via fossa craniana média, pois permite acesso aos segmentos timpânico, labiríntico e metal desse nervo, sem impor risco à audição. Pela possibilidade de acessar a porção timpânica do nervo, sem a necessidade da abertura da mastoide, o procedimento permite que se reduza o tempo cirúrgico e os riscos aos pacientes
Background: Peripheral facial palsy is characterized by the permanent or temporary interruption of the functioning of the facial muscles. The middle cranial fossa (MCF) approach has been used for the decompression of the facial nerve (FN) when hearing needs to be preserved. In this work, we describe an innovative technique for the decompression of the FN through the MCF approach that allows the direct exposure of the labyrinthine and entire tympanic segment of the FN, with the preservation of inner ear function. Methods: Twenty cadavers heads were used in this study. The reference landmarks used were the middle meningeal artery, the greater superficial petrosal nerve, the arcuate eminence, the inferior petrosal sinus and the meatal plane following the petrous apex from its most anterior and medial portion. Results: The tympanic segment of the FN presented, on average, a total length of 11 ± 0.67mm to the right, and 11.5 ± 0.60mm to the left. The longitudinal lengths of bone window in the tegmen tympani were 16.8±1.67mm to the right, and 16.8 ± 1.20mm to the left. The cross-sectional lengths of the bone window in the tegmen tympani were 5.5 ± 1.20mm and 5.0±1.75mm to the right and left sides, respectively. The average value of elliptical area formed by the longitudinal and transversal lengths of the bone window made in the tegmen tympani were 72.5 ± 22.5mm2 to the right, and 65.9 ± 30.3mm2 to the left. Conclusion: The proposed technique can be used for the surgical decompression of the tympanic, labyrinthine and meatal segments of the FN through the MCF, without imposing a risk to hearing, in addition to reducing the surgical time and the risk to patients

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Lizzo, Giulia. "Towards comparative epigenomics in hominids : a study of DNA methylation detection in ancient human and chimp bones." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC180.

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Les modifications épigénétiques sont des modulateurs importants de l'expression des gènes qui peuvent être associés à des changements phénotypiques et utilisés pour suivre l'évolution des éléments cis-régulateurs. Parmi les différents types de marqueurs épigénétiques, la méthylation de l'ADN est conservée dans le temps et peut être mesurée dans des échantillons anciens. Nous visons à réaliser une étude comparative approfondie de l'évolution de la méthylation de l'ADN dans les tissus minéralisés de la lignée des hominidés. Nous établissons ainsi des cartes de méthylation évolutives de référence en utilisant des échantillons post-mortem d'os humains et de chimpanzés, datés jusqu'à 110 ans, pour s'assurer qu'ils ont subi des transformations diagénétiques suffisantes pour imiter la situation taphonomique rencontrée dans les os anciens. En outre, cette étude inclut différents types d'os afin de réduire le bruit dû à la variabilité inter-osseuse. Différentes approches de cartographie de la méthylation ont été utilisées pour identifier celles qui conviennent le mieux à ces échantillons. Le séquençage au bisulfite des génomes entiers (BS) ou la représentation réduite BS (RRBS) ne sont pas appropriés pour les échantillons anciens en raison de la présence fréquente d'un excès important d'ADN environnemental. Nous avons donc exploré à la fois du BS ciblée par Bisulfite Patch-PCR, et une méthode haut-débit d'enrichissement de la fraction méthylée (MBD-seq). Les deux techniques nécessitent des adaptations aux caractéristiques des échantillons anciens, y compris une faible quantité d'ADN endogène, une contamination élevée de l'ADN environnemental et une fragmentation de l'ADN. Les résultats obtenus illustrent les forces et les inconvénients des stratégies choisies pour les échantillons anciens
Epigenetic modifications are important modulators of gene expression that can be associated to phenotypic changes and used to track the evolution of cis-regulatory elements. Among the different types of epigenetic marker, DNA methylation is conserved over time and can be measured in ancient samples. We aim at performing an in-depth comparative study of the evolution of DNA methylation patterns in mineralized tissues of the hominine lineage. We are thus establishing reference evolutionary methylation maps using post-mortem samples of human and chimpanzee bones up to 110 years old, to ensure that they have experienced sufficient diagenetic transformations to mimic the taphonomic situation encountered in ancient bones. Furthermore, this study includes different types of bones in order to reduce noise due to inter-bone variability. Different methylation mapping approaches were used to identify those best suited to such samples. Whole genome bisulfite sequencing (BS) or reduced representation BS (RRBS) are not suitable for ancient samples due to the frequent presence of a vast excess of environmental DNA. We thus explored both high-throughput targeted BS using Bisulfite Patch-PCR, and a methylation-based enrichment method (MBD-seq). Both techniques require adaptations to ancient sample characteristics, including low quantity of endogenous DNA, high environmental DNA contamination and DNA fragmentation. The results obtained illustrate strengths and drawbacks of the chosen strategies for ancient samples

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Santos, Fábio Pires. "Avaliação por tomografia computadorizada da correspondência entre a eminência arqueada e o canal semicircular superior." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/164380.

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O objetivo deste estudo é avaliar a correspondência anatômica entre a eminência arqueada e o canal semicircular superior na superfície da fossa craniana média. Este estudo transversal descritivo foi realizado em um hospital terciário. Setenta e cinco pacientes consecutivos (150 lados), submetidos à tomografia computadorizada de alta resolução dos ossos temporais, foram analisados por dois autores. Para cada exame, a relação anatômica entre a eminência arqueada e o canal semicircular superior foi classificada como coincidente ou não coincidente. Distâncias entre os parâmetros anatômicos de maior utilidade na cirurgia da fossa média e prevalência de deiscência do canal semicircular superior também foram estudadas. A eminência arqueada foi coincidente com o canal semicircular superior em apenas 31.3% dos casos. Não foi possível identificar a eminência arqueada em 33 exames (22.0%). Deiscência do canal semicircular superior foi encontrada em cinco casos (3.3%). Poucos milímetros separaram a cóclea do canal semicircular superior. As medidas secundárias foram caracterizadas por ampla variabilidade. A eminência arqueada não se sobrepõe sistematicamente ao canal semicircular superior e não deve ser usada rotineiramente como uma referência para a localização dessa estrutura.
The objective of this study is to evaluate the anatomical coincidence between the arcuate eminence and the superior semicircular canal at the middle cranial fossa surface. This crosssectional descriptive study was performed at a tertiary hospital. Seventy-five consecutive patients (150 sides) who underwent bilateral high-resolution temporal bone computed tomography scans were analyzed by two authors. In each scan, the anatomical relationship between the arcuate eminence and the superior semicircular canal was classified as coincident or non-coincident. Distances between the most applicable anatomical landmarks for middle cranial fossa surgery and the prevalence of superior semicircular canal dehiscence were also studied. The arcuate eminence matched the semicircular canal in only 31.3% of cases. It was impossible to identify the arcuate eminence in 33 scans (22.0%). Semicircular canal dehiscence was found in 5 cases (3.3%). A few millimeters separated the cochea from SSC; secondary measurements were characterized by broad variability. The arcuate eminence does not systematically overlie the superior semicircular canal and should not be routinely used as a reference for reaching this structure in the context of middle fossa surgery.

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Bittencourt, Aline Gomes. "Referências anatômicas ao giro basal da cóclea no assoalho da fossa craniana média para o implante coclear." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/5/5143/tde-05082014-151655/.

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Introdução: A técnica clássica para o implante coclear é realizada por meio de mastoidectomia seguida de timpanotomia posterior. O acesso pela fossa craniana média provou ser uma alternativa valiosa, embora seja usada para o implante coclear, ainda sem normatização. Objetivo: Descrever um novo acesso pela fossa craniana média que expõe o giro basal da cóclea para o implante coclear. Métodos: Estudo anatômico de ossos temporais. Foram dissecados 50 ossos temporais. A cocleostomia foi realizada mediante um acesso via fossa craniana média, na porção mais superficial do giro basal da cóclea, usando o plano meatal e seio petroso superior como as principais referências anatômicas. Foi determinada a distância entre os pontos de referência, o ângulo entre o plano meatal e a cocleostomia, e a distância entre esta estrutura e a janela redonda. Foi realizada tomografia computadorizada em 5 dos ossos temporais utilizados neste estudo. Resultados: Em todos os 50 ossos temporais, apenas a porção mais superficial do giro basal da cóclea foi aberta e tanto as escalas timpânica como a vestibular foram visualizadas. As distâncias médias ± DP, menores e maiores, entre a cocleostomia e o plano meatal foram estimadas em 2,48±0,88mm e 3,11±0,86mm, respectivamente. A distância média da cocleostomia até a janela redonda foi de 8,38±1,96mm, e daquela até o seio petroso superior 9,19±1,59mm. As distâncias médias, menores e maiores, entre a cocleostomia e o eixo longo do plano meatal a partir da sua porção mais proximal foram estimadas em 6,63±1,38mm e 8,2±1,43mm, respectivamente. O valor médio do ângulo entre a cocleostomia e o plano meatal foi igual a 22,54±7,400. As tomografias computadorizadas demonstraram a inserção do feixe de eletrodos por meio do giro basal da cóclea até o seu ápice em todas as peças submetidas a este exame. Conclusão: A técnica proposta para identificar o giro basal da cóclea é simples e confiável. Igualmente, permite a visualização da escala timpânica e a inserção do feixe de eletrodos do implante coclear através desta câmara
Introduction: The classic technique for cochlear implantation uses mastoidectomy followed by posterior tympanotomy. The middle cranial fossa approach has proved to be a valuable alternative for cochlear implantation, although the standardization of this technique is still needed. Objectives: To describe a novel approach through the middle cranial fossa for exposing the cochlear basal turn for cochlear implantation. Materials And Methods: Anatomical temporal bone study. Fifty temporal bones were dissected. A cochleostomy was performed via a middle fossa approach on the most superficial part of the cochlear basal turn, using the meatal plane and superior petrous sinus as the main landmarks. The distance between the landmarks, the angle between the cochleostomy and the meatal plane, and the distance between this structure and the round window were measured. A computed tomography was performed on 5 of the studied temporal bones. Results: In all 50 temporal bones, only the superficial portion of the cochlear basal turn was uncovered. The cochlear exposure allowed both the scala tympani and vestibule to be exposed. The mean ± SD minor and major distances between the cochleostomy and the meatal plane were estimated to be 2.48±0.88mm and 3.11±0.86mm, respectively. The mean distance from the cochleostomy to the round window was 8.38±1.96mm, and that to the superior petrosal sinus was 9.19±1.59mm. The mean minor and major distances between the cochleostomy and the long axis of the meatal plane from its most proximal portion were estimated to be 6.63±1.38mm and 8.29±1.43mm, respectively. The mean angle between the cochleostomy and the meatal plane was 22.54±7.400. The computed tomography of all 5 temporal bones demonstrated the insertion of the implant array from the cochlear basal turn towards its apex. Conclusion: The proposed technique for identifying the cochlear basal turn is simple and trustworthy. Additionally, it enables visualization of the scala tympani, facilitating the insertion of the cochlear implant array through this chamber

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Magre, Rosich Marc. "Design of tailor-made chiral ligand libraries for C-X bond forming reactions. Study of the key intermediates by NMR and DFT." Doctoral thesis, Universitat Rovira i Virgili, 2016. http://hdl.handle.net/10803/396081.

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El desenvolupament de metodologies per a l’obtenció de compostos enantiomèricament purs ha incrementat en les últimes dècades, ja que aquests productes quirals tenen un gran impacte en la societat actual perquè són la base de fàrmacs, insecticides, perfums i productes naturals, entre altres. La catàlisi asimètrica en la que el catalitzador està basat en un centre metàl·lic i un lligand coordinat al metall ha estat la tècnica més emprada en els últims anys. Aquests complexos organometàl·lics ofereixen propietats molt concretes, com per exemple la seva gran selectivitat en els processos enantioselectius i altes activitats per a reaccions específiques. La modificació del lligand serà clau per a poder obtenir grans nivells de selectivitat i altes activitats; per això els lligands han de ser modulables, la qual cosa permetria poder realitzar canvis estructurals del lligand i poder estudiar la seva influencia en la reacció, i així saber l’estructura idònia del lligand que aporti millors resultats en la catàlisi asimètrica. En aquest context, aquesta tesi doctoral es basa en la síntesi de diferents lligands quirals fosfit-nitrogen i la seva aplicació en diferents reaccions enantioselectives catalitzades per metall. Més concretament,s'ha treballat en la substitució al·lílica asimètrica catalitzada per pal·ladi, la descarboxilació protonativa d'a-aryl oxindoles catalitzada per pal·ladi, la hidrogenació asimètrica d'olefines poc funcionalitzades catalitzada per iridi, la hidroboració asimètrica d'olefines catalitzada per iridi i la addició enantioselectiva de compostos organoaluminats a aldehids catalitzada per níquel.
El desarrollo de metodologías para la obtención de compuestos enantioméricamente puros ha incrementado durante las últimas décadas, debido a la importancia de estos productos quirales en la sociedad actual, ya que son la base de fármacos, insecticidas y perfumes, entre otros. La catálisis asimétrica en la que el catalizador está basado en un centro metálico i un ligando coordinado al metal, ha sido la técnica más usada en los últimos años. Estos complejos organometálicos ofrecen unas propiedades concretas, como por ejemplo su gran selectividad y elevada actividad. La modificación del ligando será clave para la obtención de elevados niveles de selectividad y actividad. Estos ligandos han de ser altamente modulables, lo que permitiría realizar cambios estructurales y así poder estudiar su influencia en la reacción. En este contexto, esta tesis doctoral se basa en la síntesis de ligandos quirales fosfito-nitrogeno y su aplicación en diferentes reacciones enantioselectivas catalizadas por metal. Más concretamente, se ha trabajado en la sustitución alílica asimétrica catalizada por paladio; la descarboxilación protonativa de alfa aril onxindolas catalizada por paladio, la hidrogenación asimétrica de olefinas poco funcionalizadas catalizada por iridio, la hidroboración asimétrica catalizada por iridio y la adición enantioselectiva de compuestos trialquilaluminio a aldehídos, catalizada por níque
Fine chemicals and natural product chemistry rely on enantiomerically pure compounds. The growing demand on these compounds has stimulated the research for efficient asymmetric processes, which provided high activity and selectivity with minimum energy consumption and minimum generation of byproducts. In drugs and also in natural product chemistry, one enantiomer has the desired properties whereas the opposite enantiomer is either inactive or has undesirable side-effects. The discovery of synthetic routes for obtaining enantiomerically pure compounds is therefore one of the most pursued goals in chemistry. Particularly, asymmetric catalysis is one of the most attractive approach because it can provide very high reactivity and selectivity. Usually, with this strategy, a transition-metal complex containing a chiral ligand catalyzes the transformation of a prochiral substrate to one enantiomer as major product. To reach high levels of reactivity and selectivity, several reaction parameters need to be optimized. For example, the design of a chiral ligand is perhaps one of the most crucial step. In this context, this thesis focuses on the development of new chiral ligand libraries, the synthesis of new chiral catalyst and their application in the Pd-catalyzed asymmetric allylic substitution, Pd-catalyzed decarboxylative protonation of oxindoles, Ir-catalyzed asymmetric hydrogenation, Ir-catalyzed asymmetric hydroboration and Ni-1,2-addition of organoaluminum to aldehydes.

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Guennouni, Khalid El. "Les lapins du Pléistocène moyen et supérieur de quelques sites préhistoriques de l'Europe méditerranéenne : Terra-Amata, Orgnac 3, Baume Bonne, grotte du Lazaret, grotte du Boquete de Zafarraya, Arma delle Manie : étude paléontologique, taphonomique et archéozoologique." Paris, Muséum national d'histoire naturelle, 2001. https://tel.archives-ouvertes.fr/tel-00494185.

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Ce travail consiste en une analyse paléontologique, archéozoologique et taphonomique des lapins de six sites de l'Europe méditeranéenne datant du Pléistocène moyen supérieur : Terra-Amata, Orgnac 3, Baume Bonne, Lazaret, Zafarraya, Arma delle Manie. L'étude paléontologique des lapins de ces sites et la confrontation de nos données avec ceux d'autres populations fossiles, nous ont amenés, à l'instar des résultats récents sur les populations actuelles de lapins, à délaisser la subdivision des cortèges fossiles en sous-espèces et opter pour la distinction de deux populations, l'une de grande taille l'autre de petite taille. La variation cyclique de la taille que nous avons mise en évidence lors de l'étude paléontologique, est peut-être liée aux variations climatiques enregistrées au cours de ces périodes du Quaternaire. L'étude de la relation entre la taille des lapins et certains facteurs climatiques (température, précipitations et gel) estimés par la méthode de "Semi-quantification des paléoclimats", montre une forte corrélation entre la taille des lapins et les précipitations. Cette relation a également été observée chez les lapins actuels. L'étude archéozoologique des lapins de Terra-Amata, Orgnac 3, Lazaret, Zafarraya, Arma delle Manie, montre qu'avant le Paléolithique supérieur, la consommation humaine des léporidés est très sommaire. Cette consommation a été mise en évidence dans les sites du Paléolithique inférieur de Terrra-Amata, d'Orgnac 3 et du Lazaret. L'étude taphonomique détaillée de ces cinq populations met le plus souvent en évidence une origine mixte de ces accumulations : aussi bien les rapaces que les carnivores ont contribué à la formation de ces assemblages fossiles de lapins

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Aguiar, Soraia Monique Fiorati. "Avaliação in vitro de propriedades mecânicas, químicas e antimicrobianas de um selante de fossas e fissuras isento de bisfenol A." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/58/58135/tde-30082010-082800/.

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Tendo em vista o importante papel desempenhado pelos selantes de fossas e fissuras na prevenção da cárie dental, o objetivo do presente estudo foi avaliar in vitro propriedades mecânicas, químicas e ntimicrobianas do selante isento de bisfenol A Embrace Wetbond™. Para os testes de resistência ao cisalhamento e microinfiltração foram selecionados 135 terceiros molares hígidos, extraídos de humanos, divididos aleatoriamente em 6 grupos: (I) selante Fluroshield® sem contaminação; (II) selante Embrace Wetbond™ sem contaminação; (III) selante Fluroshield® contaminado com saliva; (IV) selante Embrace Wetbond™ contaminado com saliva; (V) selante Fluroshield® contaminado com água; e (VI) selante Embrace Wetbond™ contaminado com água. No estudo de resistência ao cisalhamento os dentes foram seccionados no sentido vestíbulo-lingual, a porção radicular removida e as superfícies mesiais e distais foram embebidas em resina de poliéster. Após o condicionamento do esmalte, foi aplicado o selante com o auxílio de uma matriz de Teflon®. Os espécimes foram termociclados e submetidos ao teste de resistência ao cisalhamento com uma velocidade de 0,5mm/min e célula de carga de 50kgf. Os resultados foram comparados empregando a análise de variância (ANOVA) e pós-teste de Tukey. No estudo de microinfiltração, após o condicionamento do esmalte foi aplicado o selante. Os dentes foram termociclados, selados na região da câmara pulpar com resina composta, isolados, imersos em solução de rodamina B a 0,2%, incluídos em resina acrílica, seccionados, lixados, montados em lâminas, identificados e analisados em microscópio óptico para quantificação da microinfiltração. Os resultados foram comparados empregando o teste de Kruskal-Wallis e o pós-teste de Dunn. No estudo de liberação de fluoreto por meio de água aquecida e saliva artificial foram selecionados dois selantes resinosos contendo fluoreto (Embrace Wetbond™ e Fluroshield®), uma resina composta micro-híbrida (FiltekTM Z-250) e um cimento de ionômero de vidro (Vidrion R). As determinações de fluoreto foram realizadas por potenciometria direta, utilizando o eletrodo seletivo combinado de fluoreto. Para o teste de liberação de fluoreto em saliva artificial foram confeccionados 8 corpos de prova de cada material , os quais foram armazenados em tubos plásticos contendo saliva artificial, substituída diariamente. Após 15 dias, foi avaliada a quantidade de fluoreto liberado nas soluções. Os valores obtidos em mV foram convertidos em ppm (μg/ml). Os resultados foram comparados empregando a análise de variância (ANOVA) e o pós-teste de Tukey. No estudo da atividade antimicrobiana, efetuado por meio do teste de difusão em ágar pelo método do poço, foram selecionados dois selantes resinosos contendo fluoreto (Embrace Wetbond™ e Fluroshield®), um cimento de ionômero de vidro (Vidrion R), solução de digluconato de clorexidina a 1% e soro fisiológico. Foram utilizadas cepas de S. mutans (ATCC 25175 e cepa de campo), na densidade de 1-2 da escala de McFarland. Após o período de incubação, a zona de inibição do crescimento microbiano foi mensurada. Os resultados foram comparados empregando a análise de variância ANOVA e o pós-teste de Bonferroni. O nível de significância em todas as análises estatísticas foi de 5%. No estudo da dosagem de bisfenol A foram selecionados dois selantes resinosos (Embrace Wetbond™ e Fluroshield®), dispensados em recipientes contendo 3ml de metanol. Após homogeneização e filtragem, os extratos foram analisados utilizando um espectrômetro de massas por cromatografia gasosa. Foram realizados testes com as fórmulas moleculares do bisfenol A (C15H16O2) e do Bis-GMA (C29H36O8). Com base nos resultados obtidos pôde-se concluir que o selante Embrace Wetbond™ apresentou resistência ao cisalhamento próxima do mínimo aceitável e alta microinfiltração, quando utilizado de acordo com as indicações do fabricante, em condições de contaminação com umidade. Por outro lado, esse selante apresentou elevada liberação de fluoreto, tanto em água aquecida quanto em saliva artificial, apresentou elevada atividade antimicrobiana e não apresentou liberação de bisfenol A e de Bis- GMA.
Considering the important role of pit-and-fissure sealants on the prevention of dental caries, the purpose of this study was to evaluate in vitro the mechanical, chemical and antimicrobial properties of the bisphenol A-free pit-and-fissure sealant Embrace Wetbond™. For the shear bond strength and microleakage tests, 135 sound human third molars were selected and randomly assigned to 6 groups: (I) Fluroshield® sealant without contamination; (II) sealant Embrace Wetbond™ without contamination; (III) Fluroshield® sealant contaminated with saliva; (IV) Embrace Wetbond™ sealant contaminated with saliva; (V) Fluroshield® sealant contaminated with water; and (VI) Embrace Wetbond™ sealant contaminated with water. For the shear bond strength test, the teeth were sectioned in a buccolingual direction, the root portion was removed and the mesial and distal surfaces were embedded in polyester resin. The sealant was applied to the acid-etched enamel with the aid of Teflon® matrix. The specimens were thermocycled and subjected to a shearing force at a crosshead speed of 0.5mm/min with a 50kgf load cell. Data were analyzed statistically by analysis of variance (ANOVA) and Tukeys post-test. For the microleakage assay, after acid etching of enamel, the teeth were thermocycled, the pulp chamber was sealed with composite resin, and the teeth were rendered waterproof, immersed in 0.2% B rhodamine solution, embedded in acrylic resin, sectioned, ground, mounted on glass slides, identified and analyzed with an optical microscope for quantification of microleakage. The results were compared by the Kruskal-Wallis and Dunns post-test. Two fluoride-containing resin sealants (Embrace Wetbond™ and Fluroshield®), a microhybrid composite resin (FiltekTM Z-250) and a glass ionomer cement (Vidrion R) were selected for the fluoride release test in heated water and artificial saliva. Fluoride measurements were performed with a direct potentiometry using a fluoride ion selective electrode. For the test in saliva artificial, 8 specimens of each material were fabricated and stored in plastic tubes containing artificial saliva, which as daily renewed. The amount of fluoride released in the solutions after 15 days was analyzed, and the the values obtained in mV were converted into PPM (μg/mL). The results were compared by ANOVA and Tukeys post-test. Two fluoride-containing resin sealants (Embrace Wetbond™ and Fluroshield®), a glass ionomer cement (Vidrion R), 1% chlorhexidine digluconate solution and saline were selected for the analysis of the antimicrobial activity using the agar-well diffusion assay. Suspensions of S. mutans strains (ATCC 25175 and field strain) with density equivalent to the 1-2 McFarland scale were used. After incubation, the zones of microbial growth inhibition were measured. The results were compared by ANOVA and Bonferroni post-test. A significance level of 5% was set for all statistical analyses. For the analysis of bisphenol A dosage, two resin sealants (Embrace Wetbond™ and Fluroshield®) were delivered in receptacles containing 3ml of methanol. After homogenization and filtering, the extracts were analyzed under gas chromatography-mass spectroscopy and tests were performed with the molecular formulas of bisphenol A (C15H16O2) and Bis-GMA (C29H36O8). Based on the obtained results, it may be concluded that the sealant Embrace Wetbond™ presented shear bond strength near of the minimum acceptable and great microleakage when used according to the manufacturers instructions under moisture contamination conditions. On the other hand, this sealant presented high fluoride release in both heated water and artificial saliva, showed high activity antimicrobial and did not present release of bisphenol A or Bis-GMA.

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Lesser, Juan Carlos Cisneros. "Avaliação do trauma intracoclear causado pela inserção do feixe de eletrodos do implante coclear via fossa média em ossos temporais." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/5/5143/tde-03052017-152606/.

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Introdução: O acesso pela via da fossa craniana média para colocação do implante coclear provou ser uma alternativa valiosa em pacientes com otite média crônica e cavidades de mastoidectomia instáveis, cócleas parcialmente ossificadas e em alguns casos de displasia do ouvido interno. Até hoje não existem pesquisas que descrevam se a inserção do feixe de eletrodos pela via da fossa média pode ser feita com um mínimo de traumatismo intracoclear, comparável ao observado nas inserções pela janela redonda. Objetivo: Avaliar o trauma intracoclear com dois modelos distintos de implante quando o feixe de eletrodos é inserido por cocleostomia na fossa craniana média em ossos temporais. Método: 20 ossos temporais retirados antes de 24 horas pós-óbito, foram implantados através do local da cocleostomia no giro basal da cóclea identificado no assoalho da fossa cerebral média. Dez peças receberam um implante reto e dez um pré-curvado, e foram fixadas em resina epóxi. Foi realizada tomografia computadorizada para determinar a colocação adequada do feixe eletrodos, profundidade de inserção e a distância entre a janela redonda e a cocleostomia. Por último, as peças foram polidas em série, tingidas e visualizadas por estereomicroscópio para avaliar a posição do feixe e trauma intracoclear. Resultados: A tomografia mostrou um posicionamento intracoclear do feixe de eletrodos nas 20 peças. No grupo dos implantes retos a média de eletrodos inserido foi 12,3 (10 a 14) e dos pré-curvados 15,1 (14 a 16) com uma diferença significativa (U=78, p=0,0001). A mediana de profundidade de inserção foi maior para o eletrodo pré-curvado (14,5mm) que para o reto (12,5mm) com diferenças estatisticamente significativas (U = 66, p = 0,021). Só uma das 20 inserções foi atraumática e 70% tiveram graus de trauma altos (grau 3 ou 4). Não foram observadas diferenças significativas do grau de trauma entre os dois tipos de feixes nem quando as inserções foram no sentido da janela redonda, comparado com o sentido do giro médio. Conclusões: A técnica cirúrgica utilizada permitiu a inserção do feixe de eletrodos na cóclea em todas as peças, porém sem garantir uma inserção na escala timpânica e com alto risco de trauma nas microestruturas da cóclea
Introduction: In recent years, a middle fossa approach has been described for the insertion of cochlear implants, and it proved to be a reliable alternative for implantation in patients with chronic supurative otitis media, unstable mastoid cavities with recurrent otorrhea, partially ossified cochlea and in some cases of inner ear dysplasia. Until now, no research has been done to describe if this approach allows for anatomic preservation and non-traumatic insertions comparable to those through the round window. Objective: To evaluate cochlear trauma when the cochlear implant electrode is inserted through a middle fossa approach by means of histologic and imaging studies in temporal bones. Methods: 20 temporal bones retrieved before 24 hours after death were implanted through a middle cranial fossa cochleostomy in the basal turn of the cochlea. Ten received a straight electrode and 10 a perimodiolar electrode. After reducing the bone size with preservation of the inner ear structures, the temporal bones were fixed, dehydrated and embedded in an epoxy resin. CT scans were performed to determine if an adequate direction of insertion was attained, the depth of insertion and the distance between the cochleostomy and the round window. At last, the samples were polished by micro-grinding technique and microscopically visualized to evaluate intracochlear trauma. Results: The CT-scan showed an adequate intracoclear position of the electrode in all the samples. In the straight electrode group the average number of inserted electrodes was 12.3 (10 to 14) against 15.1 (14- 16) for the perimodiolar (U=78, p=0.0001). The median depth of insertion was significantly larger for the perimodiolar electrode group (14.4mm vs. 12.5mm U=66, p = 0.021). Only one atraumatic insertion was achieved and 70% of the samples had important trauma (grades 3 and 4). No differences were identified for the trauma grades between the two groups of electrodes. Also, there were no differences in trauma if the cochlear implants were inserted in the direction of the basal turn of the cochlea or in the direction of the middle and apical turns. Conclusions: The surgical technique that was used allowed for a proper intracochlear insertion of the electrodes in all 20 temporal bones but it does not guarantee a correct scala tympani position and carries high trauma risk for the intracochlear microstructures

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Mazuela, Aragón Javier. "Design and screening of biaryl phosphite-based ligand libraries for asymmetric reduction and c-c and c-x bond forming reactions." Doctoral thesis, Universitat Rovira i Virgili, 2012. http://hdl.handle.net/10803/96665.

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Durant els últims anys, els compostos fosfit han demostrat ser lligands eficients en diverses reaccions catalitzades por metalls de transició. En aquest context, hem desemvolupat diverses lligandoteques fosfit per la seva aplicació en reaccions per obtenit productes enantiomericament purs. Més concretament hem estudiat: (a) La síntesis i aplicació de 9 lligandoteques fosfit-nitrogen en l’hidrogenació d’olefines mínimament funcionalizades catalitzada per iridi i les reaccions de substitució al•lílica i Heck catalitzades per pal•ladi. Aquests lligands s’han dissenyat mitjançant variacions sistemàtiques de diversos paràmetres del lligand. En tots els casos s’han obtingut activitats i selectivitats excel•lents (ee’s superiors als 99%) per un ampli rang de substrats. Els resultats competeixen favorablement amb els publicats prèviament en la bibliografia. (b) L’aplicació de diversos tipus de lligandoteques fosfit en la hidrofomilació de vinilarens, olefines heterocícliques i enol esters terminals catalitzada per rodi obtenint resultats prometedors (ee’ de fins el 76%).
During the last years, phosphite-containing compounds have proved to be efficient ligands for several metal-catalyzed transformations. In this context, we have developed several phosphite-containing ligand libraries for their application in reactions leading to enantiomerically pure products. More concretely we have studied: (a) the synthesis and screening of 9 phosphite-nitrogen ligand libraries in the Ir-catalyzed hydrogenation of minimally functionalized olefins, Pd-catalyzed allylic substitution and Heck reactions. These ligand libraries have been designed by systematic modification of several ligand parameters. In all cases excellent activities, regio- and enantioselectivities (ee’s up to >99%) have been obtained for a broad range of substrates. These results compete favorably with those reported previously in the literature. (b) the screening of several types of phosphite containing ligand libraries in the Rh-catalyzed hydroformylation of vinylarenes, heterocyclic olefins and 1,1’-terminal enol esters obtaining promising results (ee’s up to 76%).

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Borràs, Noguera Carlota. "Sustainable and cost-effective development of chiral metal-catalysts for C-H and C-X bond forming reactions." Doctoral thesis, Universitat Rovira i Virgili, 2018. http://hdl.handle.net/10803/664741.

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L’obtenció de compostos enantiomèricament purs ha esdevingut una necessitat que ha conduit a un important progrés en la catàlisi asimètrica, principalment usant compostos organometàl•lics quirals. Entre les diferents estratègies en l’optimització dels catal•litzadors per aconseguir elevades selectivitats i activitats, el disseny i correcta selecció de lligands quirals, modificant-ne les seves propietats és fonamental i la més utilitzada. Que un lligand sigui fàcil de sintetitzar a partir de compostos de partida accessibles i que aquests lligands siguin estables i fàcils de manipular, tenen un elevat interès en la industria. En aquest context, el principal objectiu d’aquesta tesi és la síntesi de diferents famílies de lligands quirals, acomplint els requisits prèviament esmentats, i la seva posterior aplicació a diverses reaccions asimètriques d’elevat interès industrial: hidrogenació d’olefines funcionalitzades i no funcionalitzades catalitzada per Rh i Ir, hidrogenació de cetones catalitzada per Ir, reaccions de substitució al•lílica catalitzades per Pd i reaccions de substitució propargílica catalitzada per Cu. S’han sintetitzat diverses famílies fosfit/fosfinit-tioèter/selenoèter, carbè-tioèter, amino-fosfit/fosfinit/fosfina, i varies famílies de lligands tridentats.
La obtención de compuestos enantioméricamente puros se ha convertido una necesidad que ha conducido a un importante progreso en la catálisis asimétrica, principalmente usando compuestos organometalicos quirales. Entre las diferentes estrategias en la optimización de los catalizadores para conseguir elevadas selectividades y actividades, el diseño y la correcta selección de ligandos quirales, modificando sus propiedades es fundamental y la más utilizada. Que un ligando sea fácil de sintetizar a partir de compuestos de partida accesibles y que estos ligandos sean estables y fáciles de manipular, tienen un elevado interés en la industria. En este contexto, el principal objetivo de esta tesis es la síntesis de distintas familias de ligandos quirales, cumpliendo con los requisitos previamente mencionados, y su posterior aplicación en distintas reacciones asimétricas de alto interés industrial: hidrogenación de alquenos funcionalizados y no funcionalizados catalizados por Rh y Ir, hidrogenación de cetonas catalizada por Ir, reacciones de substitución alílica catalizada por Pd y reacciones de substitución propargílica catalizada por Cu. Se han sintetizado diferentes familias de ligandos Fosfito/fosfinito-tioéter/selenoéter, carbeno-tioéter, amino-fosfito/fosfinito/fosfina, y varias familias de ligandos tridentados.
The obtaining of enantiomerically pure compounds has become a need that led to an important progress in asymmetric catalysis, mainly using organometallic chiral compounds. Among different strategies to optimize catalysts in order to obtain high selectivities and activities, the design and the correct selection of chiral ligands, modifying their properties, is fundamental and the most used strategy. Ligands easy to synthesize from readily accessible starting material and stable and easy to manipulate ligands, have a high interest in the industry. In this context, the main objective of this thesis is the synthesis of different chiral ligand families, according to the previously mentioned requirements, and their application in different asymmetric reactions with high industrial interest: Rh- and Ir-catalyzed hydrogenation of functionalized and minimally functionalized olefins; Ir-catalyzed hydrogenation of simple ketones; Pd-catalyzed asymmetric substitution of allylic acetates and Cu-catalyzed propargylic substitution. There have been synthesized different phosphite/phosphinite-thioether/selenoether, carbene-thioether, amino-phosphite/phosphinite/phosphine and various tridentated ligand families.

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Paunescu, Alexandra-Cristina. "Les rongeurs du Pléistocène inférieur et moyen de trois grottes du sud-est de la France (Vallonnet, Caune de l'Arago, Baume Bonne) : implications systématiques, biostratigraphiques et paléoenvironnementales." Paris, Muséum national d'histoire naturelle, 2001. http://www.theses.fr/2001MNHN0012.

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Les faunes de rongeurs du sud de la France, couvrant une assez longue période - du pléistocène inférieur (la grotte du Vallonnet, stades isotopiques 24 et 23), au pléistocène moyen (la grotte de la Caune de l'Arago, stades isotopiques 14 a 12, et la grotte de la Baume Bonne, stade isotopique 8 a 6) - ont constitué l'objet de notre étude. Pour ces séquences, nous avons effectué une analyse systématique, bio stratigraphique et paléoenvironnementale. La liste de rongeurs de la grotte du Vallonnet inclut Ungaromys nanus (espèce à large répartition durant le pléistocène inférieur), mais également un représentant du genre Microtus (Allophaiomys), qui est un nouvel arrivant au début du pléistocène moyen. Sa morphologie et la biométrie le rapproche du groupe Nutiensis. Dans ce même site, un représentant du genre Mimomys (Mimomys savini?), Arvicola terrestris cantiana, Pliomys lenki (à morphologie dentaire primitive), et Apodemus mystacinus, ont été mis en évidence ; ces espèces se retrouvant dans les faunes du pléistocène moyen. A la Caune de l'Arago, la liste faunique est très diversifiée, allant des espèces de steppe continentale (m. Gregalis, marmota marmota, spermophilus, c. (Allocricetus) bursae), aux espèces méditerranéennes (m. Brecciensis, hystrix). La présence du Microtus malei (espèce boréale), et Dicrostonyx torquatus (espèce arctique), met en évidence un climat très froid dans toute la séquence, à quelques exceptions près. D'autres espèces recueillies dans ce remplissage, comme Arvicola terrestris cantiana et Cricetulus (Allocricetus) bursae, constituent de bons marqueurs bio stratigraphiques. A la grotte de la Baume Bonne, des éléments nouveaux consistent dans l'arrivée - à la fin du riss - du Cricetulus migratorius, et au début du würm, du Lagurus lagurus ; ceux-ci correspondant a deux épisodes froids et arides distincts. Les différentes méthodes (de regroupement des espèces dans des catégories climato-écologiques, la méthode de calibration climatique et des cénogrammes) ont permis la reconstitution du climat et du paysage des séquences analysées. Au Vallonnet, la phase climatique correspondant à l'ensemble III était tempérée ; à la base de cette séquence, le paysage était plus ouvert, mais la quantité de matériel recueilli est insuffisante pour en tirer des conclusions. A la Caune de l'Arago le climat était froid et sec, et la steppe était prédominante (l'ensemble de la séquence, à l'exception de l'ensemble II - sol h, ou un radoucissement est signalé). A la grotte de la Baume Bonne, le climat était froid (sans connaître cependant l'amplitude enregistrée a la Caune de l'Arago), un radoucissement étant observe dans la séquence correspondant a l'ensemble IV

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Urvois, Marc. "Apports de l'estimation geostatistique de l'epaisseur des unites metalliferes dans la comprehension des mecanismes de mise en place des sediments de la fosse atlantis ii (mer rouge)." Orléans, 1987. http://www.theses.fr/1987ORLE2049.

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Cette approche geostatistique menee sur les deux niveaux sulfures (su::(1) et su::(2)) et sur le niveau oxyde (co) montre que la repartition n'est pas aleatoire. L'analyse comparative des cartes isopaques met en evidence des similitudes entre su::(2) et co et une distribution distincte entre su::(1) et su::(2), indiquant par la que la repartition des sediments est independante des conditions d'oxydo-reduction du milieu. Les teneurs en elements de base (zn, cu, fe, mn, s sulfure) sont etudiees a travers leur moyenne ponderee, par unite lithologique et par bassin. Elles montrent une migration des sources dans l'espace et le temps depuis le nord de la fosse lors du depot de su::(1), vers le sud pendant celui de su::(2). Les teneurs en elements chalcophiles dans le bassin sud-ouest, region actuelle des emergences, sont systematiquement superieures a celles du reste de la fosse. Le developpement d'un panache en milieu oxygene conduit a la precipitation preponderante d'oxydes et a la formation du niveau oxyde (co). A l'inverse, des episodes moins intenses correspondent au piegeage du fluide hydrothermal dans les saumures et au depot des niveaux sulfures (su::(1) et su::(2))

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Silva, Jaciara Miranda Gomes da. "Resistência ao cisalhamento de selante associado a dois sistemas adesivos, após contaminação salivar: influência da fotopolimerização individual e simultânea." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/58/58135/tde-13122007-110447/.

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Este trabalho teve por objetivo avaliar \"in vitro\" a resistência ao cisalhamento de um selante resinoso (Fluroshield - F) em associação com um sistema adesivo total-etch (Adper Single Bond 2-SB) e um self-etching (Clearfil S3 Bond-S3) em condições de contaminação salivar, comparando dois protocolos de fotopolimerização: individual do sistema adesivo e, em seguida, do selante ou simultânea de ambos materiais conjuntamente. Superfícies mesiais e distais de 45 terceiros molares humanos hígidos foram incluídas e planificadas, o sítio de adesão delimitado (Ø 3mm) e os corpos-de-prova alocados aleatoriamente em 6 grupos experimentais (n=15), de acordo com o tratamento empregado: I- F aplicado sobre o esmalte condicionado com ácido fosfórico a 37% (controle). Os demais grupos foram contaminados com saliva (0,01ml por 10 s) e a seguir foram aplicados: II- SB e F fotopolimerizados separadamente; III- SB e F fotopolimerizados conjuntamente; IVS3 e F fotopolimerizados separadamente; V- S3 e F fotopolimerizados simultaneamente; VI- F aplicado sem associação com adesivos sobre o esmalte condicionado e contaminado. A seguir, um cilindro de selante foi confeccionado com o auxílio de uma mesa metálica e de matriz de teflon bipartida sobre o sítio de adesão. Após armazenamento durante 24 horas a 37°C em água destilada, os espécimes foram submetidos ao teste de resistência ao cisalhamento em Máquina de Ensaios Universal (0,5mm/min; 50Kgf). As interfaces adesivas foram analisadas quanto ao tipo de fratura em microscópio óptico com 20x de aumento e para análise qualitativa, três espécimes de cada grupo, foram selecionados e analisados em microscópio eletrônico de varredura. As médias obtidas, em MPa, e os desvios padrão foram: I-12,28 (±4,29); II-8,57 (±3,19); III-7,97 (±2,16); IV-12,56 (±3,11); V- 11,45 (±3,77); e VI-7,47 (±1,99). A análise estatística, por meio da Análise de Variância e teste de Fisher, demonstrou que a contaminação salivar afetou negativamente a resistência adesiva. A associação do sistema adesivo self-etching ao selante resultou em uma média semelhante estatisticamente ao grupo controle. Comparando os protocolos de fotopolimerização, não houve diferença estatisticamente significante entre os grupos nos quais foi realizada a fotopolimerização simultânea ou individual dos materiais. Com base nestes resultados pôde-se concluir que o protocolo de fotopolimerização não afetou os valores de resistência adesiva ao esmalte condicionado e contaminado. A associação do sistema adesivo self-etching Clearfil S3 Bond ao selante Fluroshield aumentou a resistência ao cisalhamento com diferença estastísticamente significante em relação aos grupos nos quais foi utilizado o sistema adesivo Adper Single Bond 2 e com valor médio semelhante ao grupo controle, no qual o selante foi aplicado em condições ideais, na ausência de contaminação salivar.
The purpose of this study was to evaluate in vitro the shear bond strength of a resin-based pit-and-fissure sealant (Fluroshield - F) associated with a total-etch (Adper Single Bond 2 - SB) and a self-etching adhesive system (Clearfil S3 Bond - S3) under conditions of salivary contamination, comparing two curing protocols: individual light curing of the adhesive system and the sealant or simultaneous curing of both materials. Mesial and distal surfaces from 45 sound third molars were embedded, flattened and a 3-mm-diameter bonding site was demarcated. The specimens were randomly assigned to 6 experimental groups (n=15), according to the bonding technique: I - F was applied to the enamel etched with 37% phosphoric acid. The other groups were contaminated with saliva (0.01 mL during 10 s). II - SB and F were light cured separately; III - SB and F were light cured together; IV - 3S and F were light cured separately; V - 3S and F were light cured simultaneously; VI - F was applied to salivary-contaminated etched enamel without an intermediate bonding agent layer. Thereafter, a sealant cylinder was fabricated using a metallic clamping device and a split Teflon matrix placed over the bonding site. After 24-hour storage in distilled water at 37°C, shear bond strength was measured using a knifeedge blade in a universal testing machine (0.5 mm/mm; 50 kgf). The debonded interfaces were examined with an optical microscope to determine the failure modes. For a qualitative analysis, 3 specimens from each group were selected and observed under scanning electron microscopy. Means (±SD) in MPa were: I-12,28 (±4,29); II 8,57 (±3,19); III-7,97 (±2,16); IV-12,56 (±3,11); V-11,45 (±3,77); and VI-7,47 (±1,99). Statistical analysis by ANOVA and Fisher\'s test showed that salivary contamination affected negatively the bond strength. The association between the self-etching adhesive system and sealant yielded bond strength mean statistically similar to that of the control group. Comparing the curing protocols, there was no statistically significant difference between the groups with simultaneous or individual light curing of the materials. Based on these results, it may be concluded that the curing protocol did not affect the bond strength to the contaminated etched enamel. The association of Clearfil S3 Bond self-etching adhesive system to Fluroshield sealant increased the shear bond strength with statistically significant difference from the groups with Adper Single Bond 2 adhesive system, and showing mean value similar to that of the control group, in which the sealant was applied under ideal conditions, without salivary contamination.

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33

Val, Aurore. "Une approche 3D pour comprendre la taphonomie des homininés du site plio-pléistocène de Malapa, Province du Gauteng, Afrique du Sud." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0144/document.

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Le site de Malapa a livré les restes de deux homininés, associés aux restes d’autres animaux et datés à 1,98 Ma. Le degré de conservation restes osseux est remarquable dans le contexte des ensembles fossiles plio-pléistocènes retrouvés en grotte. Cela indique une combinaison de processus taphonomiques unique et non-observée dans les sites contemporains de la région. Une approche combinant analyses paléontologique, physique et spatiale des homininés et de la faune associée a été choisie afin d’interpréter la taphonomie de l’ensemble fossile, avec une attention toute particulière portée aux homininés. Des techniques de tomographie et micro-tomographie assistées par ordinateur, combinées à un logiciel de reconstruction virtuelle ont été appliquées afin de créer un modèle en 3 dimensions de la grotte et des deux squelettes d’Au. sediba. La position initiale dans laquelle les homininés ont été enfouis a été reconstruite. Les résultats indiquent que la majorité du matériel osseux a été accumulée par l’intermédiaire d’un aven-piège. Les carcasses se sont accumulées sous la forme d’un cône de débris, dans une partie profonde du système karstique présentant un accès très limité voire inexistant pour les charognards. Les deux individus ne sont peut-être pas entrés dans la grotte au même moment. Lorsque l’enfouissement a eu lieu, leur décomposition était achevée (disparition et/ou dessiccation des parties molles). Leurs os présentent des indices d’intempérisation, suggérant une période d’exposition avant l’enfouissement d’au moins plusieurs mois. Les insectes sont les principaux agents ayant modifié les restes. Les indices de momification naturelle avant l’enfouissement pour MH1 et MH2 suggèrent la préservation possible de matière organique (peau)
The cave deposits at Malapa have yielded the remains of two extremely well-preserved hominins (Australopithecus sediba) and associated fauna, dated to 1.977-1.8 Ma. The state of preservation of the hominins and some of the non-hominin material is remarkable in the context of Plio-Pleistocene fossil assemblages accumulated in caves, and indicates a unique combination of taphonomic processes, not yet observed in contemporaneous cave deposits in the region. A comprehensive approach, including palaeontological, physical, and spatial analyses of the hominins and associated fauna was undertaken to determine, describe and interpret the taphonomy of the faunal material, with particular reference to hominins. An innovative combination of Computed-Tomography (CT), micro-CT scanning and virtual reconstruction techniques was applied to create a 3D model of a selected area of the Malapa cave, with renderings of the two near-complete Au. sediba skeletons. The original burial position of the hominins was reconstructed. The results indicate that the majority of the faunal material recovered was most likely accumulated via a natural death trap. Their bodies came to rest in a deep area of the cave system with restricted access to scavengers. Results show that both individuals did probably not enter the cave system at the same time. They reached skeletonization and were slightly weathered before final burial, indicating several years of exposure before burial. Insects proved to be the primary modifiers of the hominin remains. Evidence of natural mummification before burial for MH1 and MH2 suggests the possible preservation of soft tissue

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34

Olson, Carina. "Neolithic Fisheries : Osteoarchaeology of Fish Remains in the Baltic Sea Region." Doctoral thesis, Stockholm : Department of Archaeology and Classical Studies, Stockholm University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-8215.

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35

Eppelheimer, Maggie S. "Identification of Chiari Malformation Type I Brain Morphology and Biomechanics: A Multi-Faceted Approach to Determine Diagnostic and Treatment Criteria." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1595680107882868.

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36

Benoit, Julien. "Evolution des caractères crâniens et endocrâniens chez les Afrotheria (Mammalia) et phylogénie du groupe." Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2013. http://tel.archives-ouvertes.fr/tel-01001999.

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L'étude des caractères basicrâniens et endocraniens chez les vertébrés fossiles et actuels connait un regain d'intérêt depuis quelques années. Ces caractères bénéficient en effet d'une bonne réputation en tant que marqueurs phylogénétiques, ainsi que d'un biais taphonomique favorable à leur fossilisation. C'est pourquoi dans ce volume, la région auditive et l'oreille interne (Partie I) et l'endocrâne (Partie II) de mammifères fossiles appartenant au clade des Afrotheria ont été scannés par (micro)tomographie à rayon-X, décrits, étudiés et comparés à ceux des espèces actuelles. Il s'agit plus précisément des Afrotheria fossiles que sont les Bibymalagasia (Chapitre 1), le Macroscelididae Chambius (Chapitre 2), de nombreux Hyracoidea du Paléogène (Chapitre 3) ainsi que des Tethytheria basaux tels que le proboscidien Numidotherium, l'embrithopode Arsinoitherium et le sirénien Prorastomus (Chapitre 4). Cette étude met en lumière l'intéressant signal phylogénétique fournit par les caractères de la région auditive et de l'endocrâne, capable de soutenir certains clades moléculaires (e.g. Afroinsectivora, 'Panelephantulus'). Elle montre aussi comment, sous certaines pressions de sélection, ces caractères peuvent converger de façon remarquable (e.g. chez les téthythères). Cette étude apporte aussi des éléments qui appuient l'hypothèse d'une origine Africaine des Afrotheria, ainsi que celle faisant de l'ancêtre commun des afrothères un mammifère plutôt 'ongulé' que 'insectivore'. Ces inférences fondées sur l'observation des représentants fossiles les plus anciens de ce groupe sont importants pour notre compréhension de l'origine et de la diversification des afrothères et des mammifères placentaires en général.

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37

Sponheimer, M. B., and Julia A. Lee-Thorp. "Enamel Diagenesis at South African Australopith Sites: Implications for Paleoecological Reconstruction With Trace Elements." 2006. http://hdl.handle.net/10454/3878.

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No
Elemental ratio data from archaeological and paleontological bone have often been used for paleoecological reconstruction, but recent studies have shown that, even when solubility profiling techniques are employed in an attempt to recover biogenic signals, bone is an unreliable material. As a result, there has been renewed interest in using enamel for such studies, as it is known to be less susceptible to diagenesis. Nevertheless, enamel is not immune from diagenetic processes, and several studies have suggested that paleoecologically relevant elements may be altered in fossil enamel. Here, we investigate Sr, Ba, Zn, and Pb compositions of enamel from South African karstic cave sites in an effort to ascertain whether or not this material provides reliable paleoecological information. We compared enamel data for mammals from three fossil sites aged 1.8¿3.0 Ma, all of which are on dolomites, with data from modern mammals living on dolomitic and granitic substrates. Sr/Ca and Ba/Ca are about three times higher in enamel from modern mammals on granites than those living on dolomites, stressing the need for geologically appropriate modern/fossil comparisons. After pretreatment with dilute acid, we found no evidence of increased Sr/Ca, Ba/Ca, or Pb/Ca in fossil enamel. In contrast, Zn/Ca increased by over five times at one site (Makapansgat), but much more subtly elsewhere. Ecological patterning in Sr/Ca, Ba/Ca, and Sr/Ba ratios was also retained in fossil enamel. This study suggests that Sr/Ca, Ba/Ca, and Pb/Ca data likely preserve paleoecological information from these sites, but also demonstrates that geologically similar sites can differ in the degree to which they impart certain elements (Zn in this case) to fossils. Thus, screening is probably necessary on a site-by-site basis. Lastly, further investigation of elemental distributions in modern foodwebs is necessary before elemental ratio analysis can become a common tool for paleoecological reconstruction.

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38

Backwell, Lucinda Ruth. "A critical assessment of southern African 'early hominid bone tools'." Thesis, 2014.

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39

"Probability Models of Bone Surface Modification and Application to Fossil Evidence from Ledi-Geraru (2.82 Ma) and Dikika (3.39 Ma), Afar Ethiopia." Doctoral diss., 2019. http://hdl.handle.net/2286/R.I.53916.

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abstract: Two of the defining behaviors associated with the hominin lineage are an increased reliance on tool use and the routine incorporation of animal tissue in the diet. These adaptations have been linked to numerous downstream consequences including key physiological adaptations as well as social and cognitive effects associated with modern humans. Thus, a critical issue in human evolution is how to determine when hominins began incorporating significant amounts of meat into their diets. Bone surface modifications (BSM) have long been recognized as a powerful inferential tool in identifying the differential involvement of actors responsible for altering assemblages of bone recovered from both archaeological and paleontological contexts and remain a primary source of direct evidence for butchery activities. Thus, determining the spatiotemporal context of increased carnivory in the hominin lineage relies on the accurate identification of fossil BSM. Multidecade-long debates over the agents responsible for individual BSM indicate systemic flaws in historical approaches to identification. These debates are in part due to the extreme morphological overlap between BSM produced by certain agents of modification. The primary goal of this dissertation project therefore, is to construct probability models of BSM capable of identifying individual marks with an associated probability of assignment. Using a multivariate Bayesian approach to analyze experimentally-generated BSM data, this dissertation uses two different models, one incorporating both two and three-dimensional (3D) metric and attribute data associated with individual BSM and a second model comparing 3D geometric morphometric (GM) shape data associated with BSM. The 2D/3D attribute model of BSM is used evaluate an assemblage of fossil BSM recovered from the Ledi-Geraru research area, Ethiopia (2.82 Ma) in spatiotemporal association with early Homo. The results of the analysis reveal compelling evidence for early butchery activities, suggesting hominins may have been using both modified and unmodified stone implements to process carcasses. The second model, based upon 3D GM data, was used to evaluate the earliest purported evidence for stone-mediated butchery at Dikika, Ethiopia (3.39 Ma). The Dikika marks have been argued to be the result of crocodile feeding, trampling, and butchery by three different research groups. The 3D GM model evaluates the likelihood of each of these actors in the production of the controversial Dikika marks.
Dissertation/Thesis
Doctoral Dissertation Anthropology 2019

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40

Ekdale, Eric Gregory. "Variation within the bony labyrinth of mammals." 2009. http://hdl.handle.net/2152/7862.

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The morphological diversity of the external and internal surfaces of the petrosal bone, which contains the structures of the inner ear, across a broad range of therian mammals is documented, and patterns of variation across taxa are identified. One pattern of variation is the result of ontogenetic changes in the ear region, as described for the external surface morphology of a sample of isolated petrosal bones referred to Proboscidea from Pleistocene deposits in central Texas. The morphology of the aquaeductus Fallopii for passage of the greater petrosal branch of the facial nerve supports an ontogenetic explanation for some variation within the proboscidean sample, and a sequence of ossification surrounding the aquaeductus Fallopii is hypothesized. Further ontogenetic patterns are investigated using digital endocasts of the bony labyrinth (preserved on the internal surfaces of the petrosal) constructed from CT data across a growth series of the opossum Monodelphis domestica. Strong correlation between skull length and age is found, but from 27 days after birth onward, there is no correlation with age among most dimensions of the inner ear. Adult dimensions of several of the inner ear structures are achieved before the inner ear is functional in M. domestica. Morphological variation within the inner ear of several eutherian mammals from the Cretaceous of Asia, including zhelestids from the Bissekty Formation of Uzbekistan, is described. The variation within the fossil sample is compared to that observed within extant species of placental mammals, and it is determined that the amount of variation within the Bissekty zhelestid population is within the range of that measured for extant species. Additional evolutionary and physiological patterns preserved within the walls of the bony labyrinth are identified through a high level anatomical comparison of the inner ear cavities across Placentalia as a whole. In particular, features of the inner ear support monophyly of Cetacea, Carnivora, Primatomorpha, and caviomorph Rodentia. The volumetric percentage of the vestibular apparatus (vestibule plus semicircular canals) of aquatic mammals is smaller than that calculated for terrestrial relatives of comparable body size. Thus, aspects of the bony labyrinth are both phylogenetically and physiologically informative.
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41

Hilton, Eric James. "A contribution to the comparative osteology and phylogenetic systematics of fossil and living bony -tongue fishes (Actinopterygii, Teleostei, Osteoglossomorpha)." 2002. https://scholarworks.umass.edu/dissertations/AAI3056239.

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Several recent morphological studies have addressed the interrelationships of Osteoglossomorpha, a group that sometimes is considered the sister group of all other living teleostean fishes. Many characters used in these studies were found to be poorly defined, to be coded incorrectly or illogically, or to display more variation than was described. The goal of this study is to address these concerns and contribute generally to knowledge of the morphology and systematic relationships of osteoglossomorphs. Analysis of 72 characters scored for 20 genera resulted in 2 most parsimonious cladograms. The only difference in the topologies of these cladograms is in the position of †Lycoptera (recovered as either the sister group of all other osteoglossomorphs sampled or of †Eohiodon + Hiodon). †Ostariostoma is recovered as the sister group of all non-hiodontiform osteoglossomorphs. Mormyrids are sister group of notopterids + osteoglossids (including Pantodon). Mormyrids and notopterids usually are considered more closely related to each other than to any other group; characters not included here support this relationship and future consideration of these characters must be made. † Palaeonotopterus is interpreted as sister-group of all mormyrids sampled; however, only 22% of characters could be scored for it and its resemblance to notopterids are undeniable. General problems of character definition are discussed in my review of characters used in previous analyses.

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42

Swanepoel, Elaine. "Analysis of the faunal remains of Kemp's Caves and an investigation into possible computerized classification of bones." Diss., 2003. http://hdl.handle.net/2263/28112.

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43

Cohen, Brigette Fiona. "Actualistic investigation of bone modification on leporids by caracal (Caracal caracal) and honey bagder (Mellivora capensis); an insight to the taphonomy of Cooper's Cave, South Africa." Thesis, 2014.

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Small carnivores and middle-sized mammals (mesomammals) are ubiquitous in fossil sites in South Africa, but their taphonomy is poorly understood. This study presents an actualistic investigation of bone modification by two captive small carnivores; the caracal (Caracal caracal) and honey badger (Mellivora capensis), housed at the Johannesburg Zoo. The carnivores were fed domestic rabbit (Oryctolagus cuniculus) carcasses as proxies for mesomammals and the bone modification of the resulting refuse and scatological assemblages were assessed in terms of their skeletal part representation, breakage patterns, digestive modifications and tooth marks. The investigation revealed that skeletal part representation and breakage patterns in the caracal and honey badger assemblages resembled those reported from other small carnivores. The caracal and honey badger assemblages were distinct from other carnivores in having overall light digestive modifications and a high frequency of tooth marks. Digestion was greater and tooth marks less frequent in the caracal than in the honey badger. Results were applied to the fossil assemblage of Cooper’s D which has a large assemblage of mesomammals and small carnivores. While a taphonomic analysis of Cooper’s D has not been published, initial results suggest that small carnivores had a great potential as contributors in the formation of the assemblage. The findings of this study emphasise the need for employing a variety of bone modifications in the identification of a small carnivore as an accumulator since there is rarely a single characteristic that is diagnostic for a particular carnivore.

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44

Ottoni, C., Hannah E. C. Koon, M. J. Collins, K. E. H. Penkman, O. Rickards, and O. E. Craig. "Preservation of ancient DNA in thermally damaged archaeological bone." 2009. http://hdl.handle.net/10454/6120.

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Evolutionary biologists are increasingly relying on ancient DNA from archaeological animal bones to study processes such as domestication and population dispersals. As many animal bones found on archaeological sites are likely to have been cooked, the potential for DNA preservation must be carefully considered to maximise the chance of amplification success. Here, we assess the preservation of mitochondrial DNA in a medieval cattle bone assemblage from Coppergate, York, UK. These bones have variable degrees of thermal alterations to bone collagen fibrils, indicative of cooking. Our results show that DNA preservation is not reliant on the presence of intact collagen fibrils. In fact, a greater number of template molecules could be extracted from bones with damaged collagen. We conclude that moderate heating of bone may enhance the retention of DNA fragments. Our results also indicate that ancient DNA preservation is highly variable, even within a relatively recent assemblage from contexts conducive to organic preservation, and that diagenetic parameters based on protein diagenesis are not always useful for predicting ancient DNA survival.

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45

Pei, Rui. "New Paravian Fossils from the Mesozoic of East Asia and Their Bearing on the Phylogeny of the Coelurosauria." Thesis, 2015. https://doi.org/10.7916/D88C9VC0.

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Troodontidae is an important dinosaur taxon that closely resembles birds in both morphology and biology. The evolution of troodontids is crucial for understanding evolutionary transitions between non-avialan theropods and avialans. Despite the recent discovery of several troodontid taxa across the world and many new studies of coelurosaurian relationships, an overall survey of morphological variation in troodontids and a comprehensive analysis of ingroup troodontid relationships have yet to be accomplished. In the first four chapters of this dissertation, the osteology of two new troodontid taxa and two closely related paravians are described in detail. These descriptions are based on new specimens recovered from the Mesozoic of China and Mongolia. These new taxa include the basal dromaeosaurid Microraptor zhaoianus, the basal avialan Anchiornis huxleyi, a new troodontid taxon represented by IGM 100/1323, and a second new troodontid taxon represented by IGM 100/1126 and IGM 100/3500. These paravian taxa are all small-sized, with a basal paravian body plan resembling Archaeopteryx, yet they represent members of all three major paravian lineages (Troodontidae, Dromaeosauridae and Avialae), and support the traditionally recognized paravian interrelationships. Osteological description of Microraptor zhaoianus is based on an excellently preserved new specimen BMNHC PH881. This specimen preserves significant morphological details that are not present, or are poorly preserved, in the other Microraptor specimens, including aspects of the skull, rib cage, and humerus. These new characters corroborate Microraptor as a member of the Dromaeosauridae and support the close relationship of troodontids with dromaeosaurids. Four new specimens (PKUVP 1068; BMNHC PH804, BMNHC PH822 and BMNHC PH823) of Anchiornis huxleyi reveal new osteological details of this important paravian taxon. Anchiornis huxleyi shares derived features with avialans, but it lacks derived deinonychosaurian characteristics such as a laterally exposed splenial and a specialized raptorial pedal digit II. IGM 100/1323 represents a new troodontid taxon from the Late Cretaceous Djadokhta Formation of Mongolia, diagnosed from other troodontids by the absence of the lateral groove on the dentary, a posteriorly curved pterygoid flange, a distinct spike-like process on the ischium, and elongate chevrons. Despite generally having a basal paravian body plan, IGM 100/1323 displays many derived troodontid features. IGM 100/1126 and IGM 100/3500 represent another new Late Cretaceous troodontid taxon from the Djadokhta-Formation-like rocks at Ukhaa Tolgod, Mongolia. It is unique and distinct from other troodontids in having closely packed peg-like teeth, a twisted suborbital process of the jugal, a quadratojugal with a crescentic ascending process that braces the quadrate posteriorly, reduction of the basal tubera, and presence of a posterior fossa on the proximal fibula. This new taxon is morphologically more derived than Early Cretaceous troodontids but is more primitive than other Late Cretaceous troodontids. A new and comprehensive phylogenetic analysis of coelurosaurian theropods, focusing on troodontids is presented in Chapter 5. This is an updated version of the Theropod Working Group (TWiG) analysis (2015.1). This new analysis incorporates new paravian taxa and new characters, most of which are relevant to paravians, especially the troodontids that are the focus of this dissertation. The new phylogenetic analysis agrees with previous studies on the general relationships of coelurosaurians, yet some important differences from previous TWiG analyses are present in paravians, including: 1), the Jianchang paravians are recovered as basal avialans; 2), Late Cretaceous troodontids form a monophyletic group; and 3), Jinfengopteryginae is not monophyletic.

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46

Nhauro, Godwin. "Characterization of the elemental deposits in fossils from the Cradle of Humankind in south Africa and modern bones from the same geological area." Thesis, 2010. http://hdl.handle.net/10539/8489.

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Bones are complex, composite tissues consisting of inorganic calcium phosphate crystallites precipitated in an organized organic collagen matrix. However, diagenetic processes alter the original chemical composition and structure of the mineral and the organic components of bones during the burial period through leaching, decomposition and exposure to ground water. These activities serve to enrich, deplete and/or substitute the original elements in the bone through partial or complete dissolution, erosion, precipitation, recrystallization, ion uptake by sorption and diffusion, hydrolysis, crystal growth, and repolymerization processes. Thus exogenous elements from groundwater and soil may become incorporated into bone structure in a number of ways, and may reside in pores, voids or microcracks in the bone matrix. They can also form complexes with the organic component and adsorb onto the surface of hydroxylapatite matrix via ionic exchange. Because of all these processes, the state of bone preservation varies greatly and depends on the physical and chemical characteristics of the burial environment, such as ground water and sediment composition, soil hydrology and pH, redox potential and temperature, soil solution fluoride and carbonate concentration, mechanical pressure, microbial activity, duration of interment and particle transport. The study of the diagenesis process anmd the correlation of the morphological, organic and inorganic changes in varying geochemical environments, i.e. attaining adequate reliable data for modelling (predictive) purposes remains one of the challenges in the study of the diagenesis process. Therefore, a study to characterize the morphological, mineralogical, and chemical features of fossils from Gladysvale Cave, South Africa, was done to investigate the mechanisms by which bone chemical compositions and mineralogical alterations occur during the burial period. To achieve this, several analytical techniques were employed for the analysis of the burial soils and for the characterization of both modern and fossil bones. The following methods were employed: scanning electron microscopy (SEM) for morphological studies; X-Ray Fluorescence (XRF) mapping for the identification of elemental distribution within the bone apatite matrix; Powder X-Ray Diffraction (PXRD) for mineral determination; Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP AES) for elemental determination; bone porosity and density measurements; Carbon, Hydrogen, Nitrogen and Sulphur (CHNS) for detection of light elements, particularly nitrogen, whose concentration is correlated to the collagen content of the bone; and the redox and pH measurements of the soil in which the fossil bones were buried. These analytical techniques were used to determine qualitatively and quantitatively the sample’s post-mortem elemental enrichment and/or leaching, even at trace level, and examine the elemental distribution across bone transverse sections. Analysis of the soil where fossil bones were buried indicated relatively high amounts of Al, Fe, Mn, Ba, K, Si, V and Ti than in both the fossil and modern bones. Elemental enrichment was found to be more pronounced in fossil bones showing an increase in Fe, V, Ba, Cr, Zn, Al, Cu, Ti and Mn relative to modern bones due to the incorporation of authigenic minerals from the burial environment during the fossilisation process. This pattern also confirmed how porosity affects post-mortem elemental uptake and loss, thus porous tissue of fossil bones functions as a pathway of least resistance for postmortem elemental exchange with the depositional environment. Clay particle inclusions account for the high levels of Al in fossil bones relative to modern bones. Numerous minerals were identified in all fossil specimens with carbonates, sulphides and phosphates being the most abundant. In contrast, few minerals were identified in modern specimens, with hydroxylapatite being present in all samples. Though all modern specimens were microscopically well-preserved, they were found to be poorly crystalline. The amorphous nature of these modern bones is correlated with high amounts of organic matter. In contrast, fossil bones are crystalline and this increase in crystallinity is correlated or attributed to loss of organic matter, especially the carbon contained in the carbonate hydroxylapatite mineral. The morphological and physical (i.e. porosity, density and water absorption measurements) studies of these bones at both macro- and microscopic levels revealed that all the fossil specimens had suffered severe microbial attack due to their high porosity relative to modern bones. Using the nitrogen and carbon contents as proxies for bone preservation, the values are much lower in fossil bones relative to modern bones. Modern bones have retained much of the original fragments of original bio-molecules, for instance, collagen (as revealed by high %N content) as compared to fossil bones, which have lost more than 90% of their original bio-molecules. The well preserved specimens i.e. modern bones have a high collagen content, high bulk density and low porosity values. In contrast to this, degraded fossil bones displayed a low collagen content, low bulk density, large increases in porosity. This is an indication of poor preservation state of fossil bones relative to modern bones. Redox and pH studies revealed that the fossil bones were buried on the surface under highly oxidising conditions. Such an oxygen-rich environment during dry periods is likely to have resulted in a rapid degradation of the bone’s organic matter and also favoured the activity of micro-organisms, which is visible on scanning electron microscopy results. Therefore fossil specimens show marked and complex alterations relative to their modern counterparts. These chemical and preservation disparities between the modern and fossil bones is attributed to significant diagenetic alteration, through the introduction of exogenous material to the existing matrix, and chemical alteration of the original bone matrix during the fossilisation processes. Black-coloured fossil bones are also a common sight in most South Africa caves. Questions normally arise as to whether changes in bone colour were a result of burning or surface coating from minerals. In the event that the bones were burnt, then a challenging question would be regarding the cause of the fire, i.e. whether natural or human-controlled fire. In this study, a relatively simple, non-destructive chemical procedure is applied to distinguish between burned bones and mineral-coated bones by removing the oxides from soil/mineral contaminated fossil bones, followed by characterisation of elemental composition by CHNS and ICP-AES. Any coated versus burnt fossil bones disparities were ascribed to burning effects. The methods mentioned above were used for differentiating between black fossil bones that are burned and unstained; burned and stained; and stained but not burned. The results following the cleaning process have shown that the majority of the bones were indeed burned, of which a few were burned and stained. These observations were based on comparison of the cleaning results of burnt bones against coated bones. The self-ignition temperatures of organic matter found in the vicinity of burnt bones were experimentally obtained and were assumed to have caused a spontaneous ignition of the organic matter (bat guano), resulting in burning of the bones. Results of the CHNS analysis have showed insignificant amounts of free carbon in unburned bones. The quantity of char is directly correlated to the observed blackening. Blackened bones (those which were burnt between 300oC and 400oC) contained the most char. A relatively low percentage of free carbon was found in greyish-brown bones (heated at 500oC to 600oC) due to oxidation of the carbon in the organic molecule to carbon dioxide. Little char was observed in light-coloured specimens (those heated at 700oC-800oC). The bone is chalky-white and extremely light and brittle i.e. almost complete combustion has occurred. From both CHNS and ICP-AES analysis, the burnt fossil bone contained less amounts of elements compared to their coated counterparts simply due to major alterations in bone mineralogy which occurred when bones were heated above 700oC.

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Dissertations / Theses on the topic 'Fossil bone'

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