A global extinction event has been documented in protozoan foraminifera in the late Pliocene to Pleistocene. The timing of the extinction event varied depending on location, however for Ocean Drilling Project Site 1125, disappearances occurred between 2.5 and 0.57 Ma, with the major decline approximately 1.1 Ma. In order to determine if this event affected benthic organisms other than protozoans, this study was undertaken to determine how podocopid ostracods (Crustacea) recovered Ocean Drilling Program Site 1125 responded. The present study was hindered by the small number of valves recovered; the fact that a large proportion of taxa found were undescribed and new to science; and the current state of taxonomic scheme that is under significant revision. These factors meant that a comprehensive comparison could not be achieved. Despite this, counts of ostracod valves and assessments of diversity from this study reveal a significant increase in both parameters from approximately 900-600 ka. Three possible causes were investigated to account for this increase, sediment type and sample size; affects of taphonomy, mainly dissolution; or an actual biotic 'event'. Statistical analyses showed that although sample size did have some effect, it was not the sole reason for the increase in ostracod numbers. Dissolution had an expected affect on the percentage of juveniles but no correlations were found with other sample characteristics. Sedimentation rate was investigated but this also proved unrelated. Therefore, it is suggested that the increase in total ostracod valves and diversity which occurs between 900 and 600 ka was in fact a natural, biotic 'event'. This preliminary evidence suggests that an oceanographic event that has negatively impacted on the foraminifers has had the reverse affect on the ostracod assemblage, in the sense that both population size and diversity increase during that time.

Thesis (M.A.)--Texas State University-San Marcos, 2007. / Vita. Appendices: leaves 52-78. Includes bibliographical references (leaves 79-83).

Thesis (M.A.)--Texas State University-San Marcos, 2007. / Vita. Appendices: leaves 52-78. Includes bibliographical references (leaves 79-83).

Thesis (M.A.)--Simon Fraser University, 1999. / Includes bibliographical references (leaves 106-113).

Quantifying charcoal particles preserved in sedimentary environments is an established method for estimating levels of fire activity in the past, both on human and geological timescales. It has been proposed that the morphology of these particles is also a valuable source of information, for example allowing inferences about the nature of the vegetation burned. This thesis aims to broaden the theoretical basis for these methods, and to integrate morphometric study of sedimentary charcoal with its quantification. Three key questions are addressed: firstly, whether the elongation of mesocharcoal particles is a useful indicator of fuel type; secondly, whether different sedimentary archives tend to preserve different charcoal morphologies; and finally, the critical question of how morphology affects charcoal quantification. The results corroborate the idea that grasses and trees produce mesocharcoal with distinctly different aspect ratios. However, the application of this as an indicator of vegetation change is complicated by the inclusion of species which are neither grasses nor trees, and by considerations of the effects of transportation. Charcoal morphotypes in diverse sedimentary environments are shown to be influenced by vegetation types, transportation history, and nature of the fire that produced them. Previous research has treated charcoal quantification and charcoal morphology as separate issues. Here it is shown that understanding morphology is essential for the accurate quantification of charcoal, since it affects the relationship between volumes and the two-dimensional areas from which measurements are taken. Understanding this relationship could allow such measurements to be used not just as relative measures of past fire activity, but to enable the accurate quantification of the charcoal sequestered in soils and sediments. This has important implications for our ability to understand the effects of fire on carbon cycling, and the role that fire plays in the Earth system.

Os primeiros registros de icnofósseis para o Mesozóico do Rio Grande do Sul surgiram apenas no final do Século XX. Dentre as unidades dessa Era, a Formação Guará (Jurássico Superior), é a unidade mais rica em icnofósseis (pegadas e trilhas de saurópodes, terópodes e ornitópodes e crotovinas de mamíferos(?)). Seus icnofósseis são encontrados apenas nas fácies eólicas (lençóis de areia e dunas). Nos lençóis de areia, as pegadas não estão bem preservadas devido ao intenso pisoteio e só são reconhecidas devido a deformação das laminações. Em alguns casos é possível ver esta deformação em planta e em perfil. Nas paleodunas, até o momento, só foram encontradas duas pegadas de terópode, mostrando estruturas de escorregamento e a deformação da estratificação, que ocorreu enquanto o pé do animal penetrava na areia, durante a subida na duna. Estas e outras pegadas que podem ser vistas em corte mostram uma boa preservação, indicando que uma pequena quantidade de água estava presente no substrato (< 1%), aumentando significantemente a coesão do sedimento e permitindo a preservação da pegada juntamente com as deformações verticais bem desenvolvidas, além do mais, a preservação destas indica que elas escaparam da erosão ou do pisoteio por terem sido enterradas rapidamente. No mesmo afloramento em que foram encontradas pegadas de terópodes na paleoduna foram encontradas crotovinas, identificadas pela presença de elipses de arenito maciço, com cerca de 20 cm de largura, que ocorrem cortando os foresets. Estes icnofósseis representam a única evidência de vertebrados para a Formação Guará, conseqüentemente a preservação dos mesmos é de fundamental importância para o conhecimento dos animais que viveram no Rio Grande do Sul no final do Jurássico. / In the state of Rio Grande do Sul, Brazil, eolian facies of the Guará Formation of probable Late Jurassic age, revealed footprints and trackways of dinosaurs, as well as burrows made by small vertebrates (mammals?). All the footprints and trackways are preserved in the eolian facies, including dunes and sand sheets. Footprints made in the sand sheets are not well preserved due to intense trampling and can be distinguished only by deformation of the sandstone laminations. In some cases it is possible to see this deformation on surface and in section. Tracks of theropods, ornithopods and middle-sized sauropods can be identified. Two footprints preserved in the foreset of a paleodune permitted to recognize slide structures and even identify the trackmaker, a theropod. The burrows were found at this same paleodune, cutting horizontally the foresets. They are represented by ribbons of massive sandstone – interpreted as the partial filling of the base of the burrows - covered by little blocks of stratified sandstone – suggesting the collapse of the roof inward the burrow. On an active dune, the softest, most easily deformed substrate underlies the slip face, footprints usually do not show good preservation. However, this site demonstrates that when tracks are made on the dry slip faces of dunes they can be preserved in considerable detail. Because the slip face lies within the zone of flow separation, tracks made on grainflows are better protected from wind erosion than those made on any other dune surface. The good preservation of some footprints indicates that they escaped erosion or further trampling, by rapid burial. There is no record of bone remains in the Guará Formation, consequently, the preservation of these tracks provides an unique evidence of widespread dinosaur activity in southern Brazil during the end of the Jurassic.

Submitted by Lara Oliveira (lara@ufersa.edu.br) on 2017-09-13T20:42:26Z No. of bitstreams: 1 CamiloCD_DISSERT.pdf: 2672507 bytes, checksum: d50d300dbb04da2f73d158d0ac70f5a1 (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2017-10-27T13:05:05Z (GMT) No. of bitstreams: 1 CamiloCD_DISSERT.pdf: 2672507 bytes, checksum: d50d300dbb04da2f73d158d0ac70f5a1 (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2017-10-27T13:08:25Z (GMT) No. of bitstreams: 1 CamiloCD_DISSERT.pdf: 2672507 bytes, checksum: d50d300dbb04da2f73d158d0ac70f5a1 (MD5) / Made available in DSpace on 2017-10-27T13:08:38Z (GMT). No. of bitstreams: 1 CamiloCD_DISSERT.pdf: 2672507 bytes, checksum: d50d300dbb04da2f73d158d0ac70f5a1 (MD5) Previous issue date: 2017-02-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Taphonomic studies reveals important information about how the environment affects the remains of organisms during the process of decaying. This approach can be used for the study of both ancient and recent organisms. The use of taphonomic techniques to study recent marine mammals were underused, despite its potential. This work aims to study bone material of marine mammals in search of marks left by post-mortem processes related to biotic and abiotic environmental factors in the northern cost of Rio Grande do Norte State, Brasil. According to the taphonomic signatures found in the bone material it was identified weathering processes, abrasion, necrophagy, breaks, taphonomic feedback and human actions. For the northern coast of Rio Grande do Norte skulls have better representation in strandings of marine mammals, but vertebrae have greater reliability for faunal survey. The dynamic tidal influences directly on the samples, acting as a carrier and modifying factor. Also according to the taphomonic signatures found the study area has great heterogeneity regarding the environmental dynamics that produce the signatures studied, adjacent areas can produce different signatures and distant areas can produce similar signatures / Estudos tafonômicos revelam informações importantes sobre como o ambiente afeta os restos de organismos durante o processo de decaimento. Esta abordagem pode ser utilizada tanto para estudo de organismos antigos, como para organismos recentes. A utilização das técnicas de tafonomia para estudo com mamíferos marinhos recentes foram pouco exploradas, apesar de seu potencial. Este trabalho objetiva estudar material ósseo de mamíferos marinhos em busca de marcas deixadas por processos post-mortem relacionados aos fatores ambientais bióticos e abióticos no litoral setentrional do Rio Grande do Norte, Brasil. De acordo com as assinaturas tafonômicas encontradas no material ósseo foi possível identificar processos de intemperismo, abrasão, necrofagia, quebras, retroalimentação tafonômica e ações antrópicas. Para o litoral setentrional do Rio Grande do Norte os crânios possuem uma melhor representação nos encalhes de mamíferos marinhos, porém nota-se que as vértebras possuem maior fidedignidade para levantamento faunístico. A dinâmica das marés influencia diretamente nas amostras, servindo como fator transportador e modificador. Ainda de acordo com as assinaturas tafonômicas encontradas nota-se que a área de estudo possui grande heterogeneidade quanto às dinâmicas ambientais que produzem as assinaturas estudadas, áreas adjacentes podem produzir assinaturas diferentes e áreas distantes podem produzir assinaturas semelhantes / 2017-09-13

O Sítio Linha Várzea, localizado a cerca de 4 km a nordeste da cidade de Paraíso do Sul – RS é composto por três afloramentos principais, situados às margens de três açudes artificiais de captação de água, o LV1/Base, o LV1/Topo, ambos subdivididos em Margem Leste e Oeste, e o LV2. Estes afloramentos são formados por siltitos avermelhados, característicos do Membro Alemoa da Formação Santa Maria. O conteúdo fossilífero desse conjunto de afloramentos é constituído por dicinodontes e cinodontes de tamanhos distintos, arcossauros e material icnológico representado por coprólitos atribuídos a formas herbívoras e carnívoras, constituindo-se assim, de uma assembléia fossilífera típica da Cenozona de Therapsida. O material referente aos Synapsidas é mais representativo e estágios ontogenéticos distintos podem ser evidenciados nos dicinodontes. Os espécimes apresentam variados graus de desarticulação e seguem duas formas preferenciais de preservação: bem preservados e mal preservados (“inchados”). Fósseis desarticulados são predominantes nos três afloramentos, mas estes apresentam diferenças nos aspectos de preservação. O LV1/Base possui fósseis preferencialmente “inchados” na Margem E e bem preservados na Margem W, no LV1/Topo são encontrados fósseis geralmente em bom estado de preservação, e no LV2 destaca-se a presença de um Dinodontosaurus semi-articulado, relativamente completo e “inchado”, possivelmente alvo necrofagia. A tafocenose, é interpretada como autóctone, e a análise sedimentológica e de paleoalterações indica uma variação na relação tempo de exposição/taxa de deposição para cada afloramento, com um distanciamento relativo do canal principal, num ambiente de planície de inundação. / The Linha Várzea fossiliferous site is composed of three main outcrops, at the margins of artificial lacustrine environments, located 4 km northeast of the town of Paraíso do Sul – RS. The outcrops are named LV1/Base, LV1/Top (both subdivided into Eastern and Western margins) and LV2. The outcrops are composed by reddish siltstones, characteristic of the Alemoa Member, Santa Maria Formation. The fossiliferous content is constituted by dicynodonts and cynodonts of different sizes, archosaurs and ichnologic material (coprolites), attributed to herbivores and carnivores. These fossils constitute the typical fossiliferous assemblage of the Therapsida Cenozone. Synapsids are far the most represented, with distinct ontogenetic stages recorded on dicynodonts. The specimens show all degrees of disarticulation, but main forms of preservation: well and badly preserved (“inflated”). Disarticulated fossils are the most common in all three outcrops, with slight differences on preservational processes. LV1/Base records prefferentially “inflated” fossils at the Eastern Margin, and well preserved at the Western Margin. Fossils at the LV1/Top are generally well preserved. At LV2, a semi-articulated, almost complete and “inflated” Dinodontosaurus is studied in detail, suggesting the record of necrophagy. The taphocenosis is interpreted to be autochtonous. The sedimentological and paleoalteration analysis indicate a shift on the relation exposure time/sedimentation rate for each outcrop, with a relative facies change outwards the main fluvial channel, in a floodplain environment.

Fósseis devonianos de braquiópodes infaunais denominados informalmente de lingulídeos compõem o principal objeto de estudo da presente tese. Dados tafonômicos e estratigráficos associados ao registro desses fósseis foram coletados. A abundância dos lingulídeos, suas diferentes formas de ocorrência, sua ausência em determinados afloramentos, e o fato de possuírem pares recentes (i.e. animais semelhantes que vivem nos mares atuais e que podem vir a colaborar na compreensão da paleobiologia, paleoecologia e nos processos tafonômicos dos lingulídeos fósseis) foram os fatores que influenciaram na escolha do grupo como alvo de estudo. No total analisaram-se 32 afloramentos que tiveram descritas suas litologias e estruturas sedimentares, e quando possível, foram realizadas coletas tafonômicas de alta resolução e a inserção de tais afloramentos em arcabouço de estratigrafia de sequências. Nas coletas todos os táxons encontrados foram devidamente considerados. Os afloramentos investigados distribuem-se pela sucessão devoniana da bacia sedimentar do Paraná, e atualmente encontram-se na região fitogeográfica Campos Gerais, estado do Paraná, Brasil. Para análise do material coletado foi construído um banco de dados tafonômicos. Também foram realizadas análises com microscopia eletrônica de varredura e espectroscopia de energia dispersiva, para alguns lingulídeos extremamente bem preservados, durante o período de estágio sanduíche. Ainda neste intervalo, métodos estatísticos foram aplicados com material de lingulídeos fósseis devonianos e também com material Miocênico/Eocênico contendo lingulídeos. Visitas a coleções de museus no exterior foram realizadas com intuito comparativo, uma vez que a incerteza taxonômica dos fósseis devonianos já havia adentrado a tese como mais uma problemática. As principais questões abordadas na presente tese se referem à possibilidade (1) de utilização de dados de lingulídeos atuais na interpretação do registro devoniano destes animais; (2) das características intrínsecas dos lingulídeos (i.e. concha quitinofosfática, hábito de vida infaunal) atuarem como agentes de preservação diferencial em diferentes contextos deposicionais; e por último: (3) da análise tafonômica ser dependente da identificação taxonômica precisa dos lingulídeos. Os resultados obtidos indicam que o uso de dados atualísticos pode ser efetuado, com algumas reservas; aparentemente as conchas dos lingulídeos devonianos eram mais biomineralizadas (não significa que eram mais espessas) que as conchas de lingulídeos atuais, o que aumentaria o potencial de fossilização dos lingulídeos devonianos, afetando sua tafonomia e explicando, por exemplo, a ocorrência de fragmentos de lingulídeos preservados no registro paleozóico; outro fator observado é de que há provavelmente um tendenciamento analítico negativo para a presença de fragmentos de organismos quitinofosfáticos no registro cenozóico. Além disso, as características intrínsecas dos lingulídeos podem sim ser a chave para o reconhecimento de situações deposicionais específicas, ao longo dos tratos de sistemas. Finalmente, a correta identificação taxonômica ajuda a prevenir erros tafonômicos interpretativos; no caso dos lingulídeos aqui estudados, o(s) tipo(s) de preservação dos bioclastos não auxiliou em sua classificação taxonômica específica, mas, com o uso de uma nomenclatura aberta e com o máximo de dados taxonômicos observados foi possível propor o fim do gênero Lingula, e a utilização de Lingularia cf. para se referir aos fósseis de lingulídeos do Devoniano da bacia do Paraná. / Devonian fossils of infaunal lingulid brachiopods (lingulids) are the main study object of the present dissertation. Taphonomic and stratigraphic data, associated with the record of the Devonian lingulids were collected. The main factors influencing the choice of this group as the subject of study were: abundance of specimens, their different occurrence forms, absence in some outcrops, and the presence of extant species (i.e.similar animals that live at present and that can cooperate with (paleo)biological, (paleo)ecological and taphonomical studies of the fossil forms). Thirty-two outcrops were analyzed in terms of their lithologies and sedimentary structures; when possible, high resolution taphonomic data was obtained and sequence stratigraphic analyses were preformed on the outcrops. Every fossil specimen found was properly considered, i.e. there was no tendency to collect only lingulids. The investigated outcrops pertain to the Devonian succession of the sedimentary Paraná Basin; presently they occupy the Campos Gerais phytogeographic region, Paraná State, Brazil. A taphonomic database was constructed to analyze the collected material. During the period at the Virginia Tech Institution, scanning electron microscope with energy dispersive x-ray was used to analyze lingulids of exceptional preservation. During this same period, statistical analyses were applied to Devonian and Miocenic/Eocenic fossil material containing lingulids. Visits to some museum collections were done with comparative aims, once the taxonomic problematic of the Devonian lingulids had already entered the dissertation list of issues. The main hypothesis of the present dissertation are linked to the following possibilities: (1) the use of recent lingulids to interpret the Devonian lingulid record; (2) that lingulid intrinsic characteristics (i.e. chitinophosphatic shell, infaunal life habit) could act as agents of preferential preservation in different depositional contexts; and (3) the taphonomic analysis being dependent of a true lingulid taxonomy. The obtained results indicate that actualistic data can be used but within these careful paramaters: (1) Devonian lingulids were more biomineralized (though not implying that they were thicker) when compared to recent ones, which could enhance the preservation potential of the fossil lingulids and would affect their taphonomy (this could explain the presence of fragmented lingulids in the Paleozoic record); (2) there is a negative analytical bias accounting for the absence of fragmented lingulids in Cenozoic record; (3) the intrinsic lingulid characteristics can be used as a key to recognize specific depositional environments, over successive systems tracts; and (4) the correct taxonomic identification helps to avoid taphonomical interpretative errors. In the present case, the lingulid type(s) of preservation did not help to achieve an accurate diagnosis of the genus. It was possible, instead, to abolish Lingula and use Lingularia cf. to refer to the Devonian lingulids of the Paraná Basin.

Les accumulations de petits vertébrés sur les sites archéologiques résultent d’une coprocénose ainsi que de phénomènes post-dépositionnels. La compréhension de l’ensemble des processus est nécessaire pour obtenir une interprétation viable de cette paléocommunauté. L’analyse taphonomique multi-taxons, en se basant sur les micromammifères, les lagomorphes et les oiseaux, permet d’obtenir une caractérisation fine du prédateur. Des référentiels taphonomiques ont été créés. Il s’agit d’une expérimentation sur l’impact du piétinement, d’un référentiel sur les modifications post-dépositionnelles en système karstique et d’un référentiel d’une accumulation de grand-duc. Ces référentiels ont permis une meilleure approche de certaines variables utilisées pour la caractérisation du prédateur, tels que l’isolement des dents, les traces d’altération superficielle et la représentation squelettique. Pour le site de Roc-en-Pail, la méthode multi-taxon a mis en évidence une surreprésentation de trois espèces. Les données paléoécologiques indiquent la présence d’un climat froid avec un paysage ouvert et avec des zones humides. Quant à la Caune de l’Arago, les analyses taphonomiques sur les UA P et R mettent en avant le rôle du grand-duc dans l’accumulation, ce qui induit un biais minime de représentativité. L’apport anthropique de petit gibier a été mis en évidence dans les UA G4, J et Q. D’un point de vue paléoécologique, ce site présente une succession de phases froides et de phases plus clémentes. L’interprétation de ces variations climatiques et leur corrélation aux SIM 12, 13 et 14 est complexe, deux hypothèses pour interpréter l’histoire du remplissage sont discutées. / Accumulations of small vertebrates on archaeological sites result from coprocenose as well as from post-depositionnal phenomena. The comprehension of the whole process is necessary to get a viable interpretation of the corresponding paleocommunity. The multi-taxa taphonomic analysis, based on micromammals, lagomorphs and birds, allows to obtain a precise characterisation of the predator. Taphonomic referentials, were created, they consist of experimentation on the impact of trampling, of a referential on the post-depositionnal modifications in the karstic system as well as of a referential of a great eagle owl accumulation. These referentials allowed to get a better approach of some variables used for the characterisation of the predator, such as the teeth isolation, the superficial alteration marks and the skeleton representation. The application of the multi-taxa method to the fossil assemblages showed an over-representation of three species on the site of Roc-en-Pail. The paleoecological data point out the presence of a cold climate with an open landscape as well as damp zones. For the Caune de l’Arago, the taphonomic analyses on the AU P and R emphasize the role of the great eagle owl, which induces a minimum bias of representativeness. The anthropogenic contribution of small game has been pointed out in the AU G4, J and Q. This site shows a series of cold stages and milder stages. The interpretation of these climatic variations and their correlation to MIS 12, 13 and 14 is complex, two hypotheses are discussed to interpret the infilling.