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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
151

Digitizing Dinosaur National Monument's Carnegie Quarry

Esplin, Rebecca 01 December 2017 (has links)
The Carnegie Quarry in northeastern Utah is world-renowned for the dinosaur skeletons it has produced and for its in situ display of dinosaur bones. The specimens excavated at Carnegie Quarry are displayed and curated in 20 repositories, most in North America. Data on these specimens in the forms of notes, photographs, publications, field maps, and so on, are scattered in an array of formats and institutions. The primary goal of this thesis is to develop a database linking these data with a digital map (GIS system) to make them readily accessible. To this end, a relational database was created using Microsoft Access linked to a vector-based map developed using Avenza MAPublisher running in Adobe Illustrator. Analyzing these data, the Carnegie Quarry produced 4146 specimens representing at least 105 individuals pertaining to 18 genera; 12 dinosaurs, one crocodylomorph, two turtles, Unio utahensis (a freshwater clam), and one plant. The map is based on high resolution photographs of the current quarry face merged with historic maps of previously excavated portions of the quarry. Previous attempts to develop a complete map were hindered by the large number of maps, primarily from four institutions that excavated at the site, and the lack of an accurate map of the current quarry face (due to substantial relief, the 67° dip of strata, and the lack of a permanent grid). The new maps will provide invaluable insights into the depositional setting, taphonomy and paleoecology of the site. The map and database provide a single access point for data on specimens from 20 widely dispersed repositories linking them their original quarry positions. This expandable tool will be invaluable to scientists and the caretakers of Dinosaur National Monument and is recommended for adoption at other quarries.
152

Taphonomie de l'assemblage de macrorestes fossiles de vertébrés du Lagerstätte d'Angeac-Charente (Crétacé inférieur, Charente, France) / Taphonomy of the assemblage of vertebrate fossil macroremains of the Lagerstätte of Angeac-Charente (Lower Cretaceous, Charente, France)

Rozada, Lee 04 June 2019 (has links)
Les opportunités de reconstituer l’écologie et les comportements d’individus et d’espèces de vertébrés éteints sont rares. Plusieurs grands assemblages de vertébrés fossiles datant de la fin du Jurassique au début du Crétacé fournissent des informations sur la biodiversité et les communautés de vertébrés terrestres. Cependant, à l’exception du Lagerstätte de Las Hoyas (Crétacé inférieur, Espagne), les fossiles de ces assemblages ont été retrouvés sur un large éventail géographique, stratigraphique et/ou temporel. Cette thèse présente les résultats d’une étude taphonomique, couplée avec des données néotaphonomiques, paléontologiques, ichnologiques, sédimentologiques et géochimiques, de l’assemblage de macrorestes fossiles de vertébrés du site du Crétacé inférieur d’Angeac-Charente, situé dans l’Ouest de la France. Neuf campagnes de fouilles menées depuis 2010 ont permis de récolter plusieurs milliers de macrorestes de vertébrés appartenant à 16 taxons différents, auxquels viennent s’ajouter d’abondants microrestes appartenant à 27 taxons de vertébrés supplémentaires, plusieurs centaines de coprolithes de termites et de vertébrés riches en inclusions végétales et osseuses, des centaines de remplissages naturels d’empreintes de dinosaures, de nombreux restes de végétaux, des moules de mollusques bivalves et gastropodes, ainsi que des ostracodes. L’ensemble sédimentaire est dominé par des argiles de décantation interrompues par des dépôts localisés de plus haute énergie (cours d’eau, inondation) déposé dans un environnement de zone humide de type marécage. De nombreuses figures de déformations synsédimentaires formées en milieu liquide sont conservées sous forme de « scènes figées ». Des empreintes attribuées à l’ichnogenre Deltapodus et conservées sous forme de remplissages de dépôt direct ont été produites par un groupe multigénérationnel de stégosaures. De nombreuses empreintes de sauropodes sont conservées en 3-D ou en 4-D sous forme de remplissages de profondeurs variables. L’assemblage osseux est multitaxique, très diversifié et comprend des taxons terrestres, amphibies et aquatiques d’eau douce. Il contient une combinaison de macrofossiles et microfossiles et s’est formé de manière complexe, avec l’intervention de multiples processus d’origine biologique, écologique et physique. Il est dominé par les dinosaures, en particulier une nouvelle espèce d’ornithomimosaure non-ornithomimidé, dont de nombreux restent résultent d’une mort en masse d’un troupeau multigénérationnel dominé par des juvéniles et subadultes. D’abondants restes de sauropodes ont été transportés sur une plus ou moins grande distance avant d’être déposés sur le site. De nombreuses traces de morsure à la surface des restes de carapaces appartenant à plusieurs individus de tortues Pleurosternon bullockii résultent du comportement de prédation du crocodylomorphe Goniopholis, avec l’utilisation de la technique « casse-noix ». Les modifications osseuses post-dépositionnelles, comme la désarticulation, les déplacements, réorientations, fractures et traces de surface, résultent principalement de l’intense piétinement par les dinosaures. Le Lagerstätte d’Angeac-Charente ouvre une fenêtre d’une résolution spatiale et temporelle exceptionnellement fine sur un écosystème terrestre ouest-européen du tout début du Crétacé dont les organismes étaient en interaction directe entre eux et avec leur environnement. / Opportunities to reconstruct the ecology and behaviour of individuals of extinct vertebrate species are rare. Several large assemblages of fossil vertebrate dating from the late Jurassic to the early Cretaceous provide information on biodiversity and terrestrial vertebrate communities. However, with the exception of the Lagerstätte of Las Hoyas (Lower Cretaceous, Spain), the fossils of these assemblages have been found over a wide geographical, stratigraphic and/or temporal range. This PhD thesis presents the results of a taphonomic study, coupled with neotaphonic, paleontological, ichnological, sedimentological and geochemical data, of the assemblage of vertebrate fossils macro-remains from the Lower Cretaceous site of Angeac-Charente, located in the western France. Nine excavation campaigns carried out since 2010 allowed to collect thousands of vertebrate macroremains belonging to 16 different taxa, to which are added abundant microremains belonging to 27 additional vertebrate taxa, hundreds of termite and vertebrate coprolites rich in plant and bone inclusions, hundreds of natural casts of dinosaur tracks, numerous plant remains, bivalve and gastropod casts, as well as ostracods. The sedimentary assemblage is dominated by settling clays interrupted by localized deposits of higher energy deposited in a swampy wetland environment. Many synsedimentary deformations formed in liquefied sediments are preserved as "frozen scenes". Tracks attributed to the ichnogenre Deltapodus and preserved as direct deposit infills were produced by a multigenerational group of stegosaurs. Many sauropod footprints of various depths are stored in 3-D or 4-D. The bone assemblage is multitaxic, highly diversified and includes terrestrial as well as freshwater amphibian and aquatic taxa. It contains a combination of macrofossils and microfossils and has been formed in a complex way, with the intervention of multiple processes of biological, ecological and physical origin. It is dominated by dinosaurs, especially a new species of non-ornithomimid ornithomimosaur, many of whom remain resulting from a catastrophic mass death of a multigenerational herd dominated by juveniles and subadults. Abundant sauropod remains were transported by water currents over various distance before their deposit on the site. Many bite marks on the surface of shell remains belonging to several Pleurosternon bullockii turtle individuals result from the predatory behaviour of the crocodylomorph Goniopholis, with the use of the "nutcracker" technique. Post-depositional bone modifications, such as disarticulation, displacements, reorientations, fractures, fissures and surface marks, result mainly from intense trampling by dinosaurs. The Angeac-Charente Lagerstätte opens a window of exceptionally fine spatial and temporal resolution on a western European terrestrial ecosystem from the very beginning of the Cretaceous whose organisms interacted directly with each other and with their environment.
153

Une approche 3D pour comprendre la taphonomie des homininés du site plio-pléistocène de Malapa, Province du Gauteng, Afrique du Sud / A 3D approach to understand the taphonomy of the early hominins from the plio-pleistocene cave site of Malapa.

Val, Aurore 28 February 2014 (has links)
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.
154

Assessing the formation and preservation of organic signatures in extreme environments in the context of the ExoMars 2020 rover mission

Reinhardt, Manuel 17 May 2019 (has links)
No description available.
155

Taphonomy of cervids of a Southern Oregon coast site using scanning electron microscopy and X-ray diffraction

Bodman, Susannah L. 24 June 2002 (has links)
One taphonomic problem plaguing archaeologists and physical anthropologists, whether their research is in North American cultures or hominid sites in Africa, is the difficulty in distinguishing bone altered by burning and heating from bone altered by soil processes. Archaeologists working to understand the recent prehistory of the Southern Oregon Coast face the same challenge. Two relatively new tools were investigated to determine their usefulness to resolving this problem. These are scanning electron microscopy (SEM) and X-ray diffraction (XRD). SEM has been well-tested in African sites and experimental studies to identify hominid-created cut marks on bone and to reconstruct heating temperatures of burnt bone. However, SEM and its ability to sample chemistry, as well as XRD's ability to detect diagentic alteration in bone minerals, have not been tested on material from coastal Oregon. The purpose of this research was: (1) to test these methods to see whether they could distinguish between burning and soil alteration, using cervid bone from site 35CS43 near Bandon, Ore., as a test sample, and (2) to see whether the result, paired with archaeological, ethnographic, taphonomic and faunal evidence, could be used to understand how the Coquille were procuring, processing and cooking cervids as insights into their adaptation. The outcome suggests that SEM and XRD, without use of other evidence, are unable to distinguish between burning and soil alteration because the similarities between the two lie not only in changes to the bone's macrostructure (discoloration) but also in bone chemistry, where it was hoped differences could be found. However, these techniques, when paired with the other lines of evidence, did provide insights in understanding the taphonomy and the Coquille's use of cervids - the interaction of bone and soil; the extent of mimicry between burning and soil alteration; and ultimately that discoloration of cervid bone at 35CS43 was likely due to soil alteration, that burning as the result of fire roasting was most likely not occurring at the site, and that the Coquille employed other methods of cooking. / Graduation date: 2003
156

The Paleoecology and Biogeography of Ordovician Edrioasteroids

Lewis, Rene Anne 01 August 2011 (has links)
All organisms are subjected to the living and non-living influences of their surroundings. They derive their energy and essential materials, such as sunlight and nutrients, from their environment, sharing their world not only with members of their own species but also with members of other species. These interactions are central to the survival of the organism, forming reciprocating and integrated systems with other members of their environment. Paleoecology uses the fossil record to interpret and reconstruct life habits of past organisms and environments. By examining well-preserved fossil populations we can assess the relationship between the organisms and their surrounding environment, their distribution within their environment, and the nature of their interactions. Edrioasteroids, an extinct clade of gregarious, obligate-encrusting echinoderm typical of the Late Ordovician, are rarely encountered in the fossil record as their multi-part skeleton rapidly disarticulates post-mortem. Therefore, the discovery of large pavements encrusted by articulated edrioasteroids indicates that obrution, or a sudden input of sediment that smothers the benthic community, occurred. The near instantaneous nature of obrution allows for the examination of a zero-time-averaged census assemblage rather than a time-averaged death assemblage. This dissertation aims to increase our understanding of the paleoecology and biogeography of Ordovician edrioasteroids in three chapters. The first study examines a carbonate hardground encrusted with four species of isorophid edrioasteroids collected from Upper Ordovician strata near Maysville, Kentucky. Detailed paleoecologic analyses include edrioasteroid age structure, thecal orientation, inter- and intraspecific spatial utilization and settlement patterns, and degree of post-mortem disarticulation. Chapter two examines edrioasteroid paleoecology on Upper Ordovocian shell pavements using a brachiopod shell pavement from Florence, Kentucky and a bivalve shell pavement from Sharonville, Ohio. The results are then compared with those from the Maysville hardground. The final chapter of this dissertation summarizes the paleogeographic distribution patterns of the edrioasteroids during the Ordovician. For this study we collected the geographic distribution data for Ordovician edrioasteroids from published faunal reports and plotted these occurrences on paleogeographic maps with the hope that this information will help better predict localities where additional specimens of Ordovician edrioasteroids may be found.
157

A Morphological and Geochemical Investigation of Grypania spiralis: Implications for Early Earth Evolution

Henderson, Miles Anthony 01 August 2010 (has links)
Macroscopic “carbonaceous” fossils such as Grypania, Katnia, Chuaria, and Tawuia play a critical role in our understanding of biological evolution in the Precambrian and their environmental implications. Unfortunately, understanding of these fossils remains limited by their relative simplicity of form, mode of preservation, and broad taphonomic variability. As a result, debate continues as to even the fundamental taxonomic affinity of the organisms. Megascopic coiled forms (i.e. Grypania and Katnia), for instance, have been interpreted as trace fossils, multicellular algae, prokaryotic filaments, macroscopic bacteria, cyanobacteria, or a transitional form from macroscopic to megascopic bacterial life. Similarly, Chuaria and Tawuia have been interpreted as compressed prokaryotic colonies, algae or algal reproductive stages, and multicellular plant material. Accessibility of new material and increasingly sophisticated means of analysis warrant a new look at these ancient fossils. Understanding the biological affinity of Grypania, in particular, is critical because current opinion is split as to whether these megascopic structures are more likely represent either multicellular bacteria or multicellular algae. Confirmation of either a bacterial or algal affinity would strongly influence fundamental understanding of biospheric evolution, particularly in terms of ocean oxygenation and the availability of bioessential trace metals. Although estimates for the degree of oxygenation required for a Grypania-like multicellular algae are only about 10 % present atmospheric levels (PAL), this estimate is still substantially higher than estimates based on geochemical data suggesting that oxygen levels may not have reached 10% PAL until the latter Neoproterozoic. It has been hypothesized that protracted oxygen of the Proterozoic biosphere may have played a critical role in the availability of redox-sensitive nutrients necessary for bacterial nitrogen fixation and the limiting of eukaryotic evolution. Within this context, our understanding of the taxonomic affinity of Grypania may profoundly affect our understanding of Earth’s biospheric evolution. This thesis provides morphological and geochemical analyses of Grypania spiralis from more than 100 newly collected specimens from the Belt Supergroup for comparison to previously collected specimens from all other known Grypania-bearing localities. Data is used to explore questions regarding the morphology, structural complexity, mode of preservation, and chemistry of fossil material, and to hypothesize on the taxonomic affinity of Grypania spiralis and its implications for biospheric evolution.
158

Cut mark analysis of protohistoric bison remains from EfPm-27 utilizing the scanning electron microscope

Pollio, Cara Jean 13 April 2009
EfPm-27 is a Protohistoric bison pound and processing site located in Fish Creek Park in Calgary, Alberta. The site exhibited the presence of metal tools and macroscopically deceptive cut marks suggesting the potential for the presence of both metal and stone cut marks. Moulds of selected cut marks from the assemblage were made and examined with the scanning electron microscope (SEM) to verify or negate the use of metal tools for butchery at the site. SEM images of the cut mark moulds reveal micromorphology that is similar to experimental and published stone tool cut mark SEM images. No evidence for the use of metal tools for butchering was identified. Protohistoric sites research could benefit from the use of SEM analysis of cut marks to distinguish between stone and metal tool use. This would provide important secondary evidence for metal trade items in scenarios where such artifacts may be beyond recovery. Conversely, the presence of metal artifacts at a site does not necessarily imply that they were used for butchery and this assertion must be verified by the presence of metal cut marks.
159

Cut mark analysis of protohistoric bison remains from EfPm-27 utilizing the scanning electron microscope

Pollio, Cara Jean 13 April 2009 (has links)
EfPm-27 is a Protohistoric bison pound and processing site located in Fish Creek Park in Calgary, Alberta. The site exhibited the presence of metal tools and macroscopically deceptive cut marks suggesting the potential for the presence of both metal and stone cut marks. Moulds of selected cut marks from the assemblage were made and examined with the scanning electron microscope (SEM) to verify or negate the use of metal tools for butchery at the site. SEM images of the cut mark moulds reveal micromorphology that is similar to experimental and published stone tool cut mark SEM images. No evidence for the use of metal tools for butchering was identified. Protohistoric sites research could benefit from the use of SEM analysis of cut marks to distinguish between stone and metal tool use. This would provide important secondary evidence for metal trade items in scenarios where such artifacts may be beyond recovery. Conversely, the presence of metal artifacts at a site does not necessarily imply that they were used for butchery and this assertion must be verified by the presence of metal cut marks.
160

Sedimentology, Geochemistry, and Geophysics of the Cambrian Earth System

Creveling, Jessica 01 November 2012 (has links)
Within this dissertation, I document how—and hypothesize why—the quirks and qualities of the Cambrian Period demarcate this interval as fundamentally different from the preceding Proterozoic Eon and succeeding periods of the Phanerozoic Eon. To begin, I focus on the anomalous marine deposition of the mineral apatite. Sedimentary sequestration of phosphorus modulates the capacity for marine primary productivity and, thus, the redox state of the Earth system. Moreover, sedimentary apatite minerals may entomb and replicate skeletal and soft-tissue organisms, creating key aspects of the fossil record from which paleontologists deduce the trajectory of animal evolution. I ask what geochemical redox regime promoted the delivery of phosphorus to Cambrian seafloors and conclude that, for the case of the Thorntonia Limestone, apatite nucleation occurred under anoxic, ferruginous subsurface water masses. Moreover, I infer that phosphorus bound to iron minerals precipitated from the water column and organic-bound phosphorus were both important sources of phosphorus to the seafloor. Petrographic observations allow me to reconstruct the early diagenetic pathways that decoupled phosphorus from these delivery shuttles and promoted the precipitation of apatite within the skeletons of small animals. Together, mechanistic understandings of phosphorus delivery to, and retention within, seafloor sediment allow us to constrain hypotheses for the fleeting occurrence of widespread apatite deposition and exquisite fossil preservation within Cambrian sedimentary successions. Next, I describe and quantify the nature of carbonate production on a marine platform deposited at the hypothesized peak of Cambrian skeletal carbonate production. I find that fossils represent conspicuous, but volumetrically subordinate components of early Cambrian carbonate reef ecosystems and that despite the evolution of mineralized skeletons, Cambrian carbonate platforms appear similar to their Neoproterozoic counterparts, primarily reflecting abiotic and microbial deposition. Finally, I investigate the geodynamic mechanism responsible for rapid, oscillatory true polar wander (TPW) events proposed for the Neoproterozoic and Phanerozoic Earth on the basis of paleomagnetic data. Using geodynamic models, I demonstrate that elastic strength in the lithosphere and stable excess ellipticity of Earth’s figure provided sufficient stabilization to return the pole to its original state subsequent to convectively-driven TPW. / Earth and Planetary Sciences

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