There is strong evidence that variations in seawater chemistry occurred during the Phanerozoic Eon. Of particular importance are the changes in the Mg2+/Ca2+ ratio because they have been attributed to the oscillations between “calcite” and “aragonite seas” over time. In addition to the Mg2+/Ca2+ ratio variations, there were also major changes in pCO2 levels and alkalinity that could also affect the calcium carbonate (CaCO3) polymorph that precipitates from seawater. Experiments were conducted in seawater where the initial alkalinity and pCO2 levels were varied and then slow degassing of CO2 resulted in a gradual increase of saturation state with respect to CaCO3 and eventually nucleation. The pH was continually monitored throughout the experiments and it was used in combination with the initial alkalinity to calculate the pCO2 and saturation state of aragonite (sigmarag) at the time of nucleation. The morphology and mineralogy of the precipitates were determined using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis, respectively. It was observed that the initial alkalinity greatly affected the nucleation pCO2 value and the CaCO3 polymorph that was precipitated. In seawater with Mg2+/Ca2+=1.2 and ~10 mM alkalinity and a pCO2 below 2,500 μatm, calcite that was overgrown with aragonite was the dominate polymorph nucleated, while pure aragonite precipitated when the pCO2 was above 2,500 μatm. Seawater with Mg2+/Ca2+=1.2 and a wide range of initial alkalinities (5-50 mM) produced variable results. Seawater with Mg2+/Ca2+=1.7 produced only aragonite at lower alkalinities, but calcite was nucleated when the alkalinity and pCO2 values were exceptionally high, typically above 11 mM. These results point to the need to also consider the effects of the carbonic acid system in the “critical” Mg2+/Ca2+ region of about 1 to 2 for “calcite seas” and “aragonite seas” at various times throughout the Phanerozoic Eon.

Palaeontological data are essential for determining patterns of biological diversity through geological time, enabling the investigation of important macroevolutionary events such as mass extinctions and explosive radiations. Most studies utilise proxies of taxonomic diversity. A more complex undertaking is to assess patterns of morphological variety (disparity) through time, revealing the manner in which groups evolved through their ‘design space’. Many published studies indicate clades tend to reach their maximum disparity early in their evolutionary history. Whether this is a real biological pattern has yet to be tested. Chapter 1 tackles the evolution of disparity in metazoans across the Phanerozoic. The results of a meta-analysis of disparity in 98 extinct clades indicate early high disparity is the most prevalent pattern across the Phanerozoic but finds no clear trends through the Phanerozoic. Mass extinction ended clades were the exception, tending to result in late high disparity. Chapters 2-4 focus on the clade Bivalvia for disparity and diversity analysis. Bivalves are ecologically and taxonomically diverse and have an excellent fossil record but have not been scrutinised using the latest diversity techniques, and have been untouched by disparity analysis. Chapter 2 uses the most up to date stratigraphic ranges and techniques to revise the bivalve Phanerozoic diversity curve. The results show bivalve Phanerozoic diversity is robust to the sampling and fossil record biases examined. Chapter 3 uses data provided as part of collaboration between Martin Hughes, Dr Joseph Carter (University of North Carolina) and Dr Matthew Wills (University of Bath) to address the disparity of bivalves across the Palaeozoic. The results find disparity rises across time but not decreased by mass extinctions. Chapter 4 conducts the first large scale analysis of disparity across latitude. The results find that bivalve disparity across latitude is unchanging and stable compared to the steep gradient of bivalve diversity.

O objetivo deste trabalho de pesquisa é o de buscar entender os tempos e eventos que determinaram as grandes mudanças climáticas no Éon Fanerozoico. Técnicas são constituídas, metodologias estabelecidas, e por vezes são aceitas como sendo as verdades científicas. Com as inovações nas técnicas, com o mudar das ciências, mudam as evidências, mudam as verdades, fazendo mudar nossa percepção do passado. Este trabalho apresenta elementos para um debate sobre o clima da Terra no Fanerozoico, estabelecido a partir de pesquisas bibliográficas sobre evidências passadas e atuais. / The goal of this research work is to understand the times and events that determined the great climatic changes in the Phanerozoic Eon. Techniques are constituted, methodologies are established, and are sometimes accepted as scientific truths. With innovations in techniques, with the change of science, change the evidence; change the truths, making change our perception of the past. This paper presents elements for a discussion on the Earth\'s climate in Phanerozoic established from bibliographical research on past and current evidences.

A análise cladística de Conulariidae (Cnidaria) é aqui apresentada, e está fundamentada na hipótese de que os agrupamentos taxonômicos (famílias, subfamílias), propostos no ?Treatise on Invertebrate Paleontology? (TIP), não são filogeneticamente válidos. O estudo apresentado levou em consideração a revisão do material depositado em coleções do Brasil e do exterior e teve como objetivos principais (1) a análise cladística dos conulários, procurando determinar o escopo do grupo e (2) discutir as implicações dos dados obtidos na sistemática de Conulariidae. Ao todo, 17 caracteres foram estabelecidos e descritos para a anatomia externa e interna da teca de conulários, envolvendo 15 táxons para o grupo-interno (Archaeoconularia, Climacoconus, Conularia, Conularina, Ctenoconularia, Eoconularia, Metaconularia, Paraconularia, Pseudoconularia), incluindo 6 gêneros (Teresconularia, Vendoconularia, Baccaconularia, Glyptoconularia, Notoconularia e Reticulaconularia), propostos após a publicação do TIP. Cubozoa, Stauromedusae, Coronatae e Semaeostomeae constituíram o grupo-externo. A análise de parcimônia obteve 124 cladogramas igualmente mais parcimoniosos. A análise de pesagem sucessiva resultou em 3 cladogramas mais parcimoniosos. Os cladogramas resultantes da análise de pesagem sucessiva indicam que os táxons terminais Conularina, Baccaconularia e Glyptoconularia aparecem em diferentes posições. O cladograma de consenso semi-estrito, gerado após a análise de pesagem sucessiva, mostrou-se totalmente resolvido, representando uma das 124 árvores originais encontradas. No cladograma de consenso semi-estrito não havia caracteres suficientes que sustentassem todos os clados pela otimização ACCTRAN ou DELTRAN. Dessa forma, o clado ((Archaeoconularia, Metaconularia) (Conularina (Notoconularia (Climacoconus (Paraconularia, Reticulaconularia)))))) foi colapsado, formando a politomia entre ((Baccaconularia, Glyptoconularia) (Archaeoconularia, Metaconularia) (Conularina (Notoconularia (Climacoconus (Paraconularia, Reticulaconularia))))))), sustentada pela presença de ornamentação externa na região da linha mediana. Os dados mostram que o grupo-interno é monofilético, sustentado pela forma geométrica da teca, em seção transversal, na região oral, quadrada e presença de periderme mineralizada, constituindo as autapomorfias dos conulários. O clado (Notoconularia (Climacoconus (Paraconularia, Reticulaconularia))) é distinguido pela disposição da ornamentação entrelaçada no sulco da aresta, forma angulada do sulco da aresta e cordões do tipo trocoidal. O encontro alternado dos cordões na região da linha mediana caracteriza o clado composto por (Climacoconus (Paraconularia, Reticulaconularia)). O clado (Paraconularia, Reticulaconularia) não apresenta sinapomorfias, sendo sustentado por caracteres homoplásticos. Do ponto de vista taxonômico, não houve a possibilidade de identificação dos agrupamentos (Conulariinae, Paraconulariinae e Ctenoconulariinae) presentes no TIP. Dessa forma, esses não são consistentes, pois não são sustentados por sinapomorfias, mas sim por simplesiomorfias e homoplasias. Os gêneros de conulários analisados foram agrupados no filo Cnidaria, classe Scyphozoa, ordem Conulariida e família Conulariidae. A partir do exame de 1450 exemplares, as espécies Conularia milwaukeensis, C. quíchua, C. albertensis, C. distincta, C. crenulata, C. expansa, C. tuberculata, C. acutilirata, Paraconularia ulrichana, P. africana, P. acuminata, P. pulcheria, P. derwentensis, Reticulaconularia baini e Baccaconularia cf. robinsoni tiveram estruturas morfológicas reconhecidas (septos, carenas, articulação, disposição da ornamentação no sulco da aresta, ornamentação externa na região da linha mediana) não descritas previamente. Em adição, foram realizadas as revisões sistemáticas de membros do grupo-interno, incluindo a reinterpretação de Vendoconularia (Formação Ust? Pinega, Proterozóico, Onega River, Rússia), Malvinoconularia (Formação Belén, Devoniano, Santa Cruz de La Sierra, Bolívia) e Baccaconularia (Formação Saint Lawrence, Cambriano Superior, Estados Unidos), a redescrição sistemática de C. milwalkeensis (Formação Little Cedar, Iowa e Formação Milwaukee, Wisconsin, Devoniano, Estados Unidos) e, finalmente, a descrição de Teresconularia, um novo gênero do Ordoviciano da Argentina. / The Conulariidae (Cnidaria) cladistic analysis is here presented being founded on the hypothesis that the classical suprageneric groups (families and subfamilies) recognized in the ?Treatise on Invertebrate Paleontology? (TIP), are not phylogenetically valid. The study included the revision of fossil material deposited in Brazilian and international scientific collections, having the following objectives (1) the conulariid cladistic analysis to elucidate the taxonomic scope of this group and (2) the discussion of the implications of the cladistic data gathered on Conulariidae systematic. A total of 17 characters were scored for the external and internal thecae morphology of 15 ingroup taxa (Archaeoconularia, Climacoconus, Conularia, Conularina, Ctenoconularia, Eoconularia, Metaconularia, Paraconularia, Pseudoconularia), including 6 genera (Teresconularia, Vendoconularia, Baccaconularia, Glyptoconularia, Notoconularia and Reticulaconularia), proposed after the publication of the TIP. Cubozoa, Stauromedusae, Coronatae and Semaeostomeae constituted the outgroup. Unweighted analysis of the data matrix yielded 124 trees. Successive weighting analysis resulted in 3 trees. The successive weighting trees indicated that the taxa Conularina, Baccaconularia and Glyptoconularia appear in different positions. The semi-strict tree is totally resolved, representing one of the 124 original trees found. In the semi-strict tree not all clades were supported by characters using ACCTRAN or DELTRAN optimizations. The clade ((Archaeoconularia, Metaconularia) (Conularina (Notoconularia (Climacoconus (Paraconularia, Reticulaconularia)))))) was collapsed, forming a politomy among ((Baccaconularia, Glyptoconularia) (Archaeoconularia, Metaconularia) (Conularina (Notoconularia (Climacoconus (Paraconularia, Reticulaconularia))))))), that was supported by the presence of external ornamentation in the midline. The data shows the internal group as monophyletic and is supported by the theca geometry in the oral section quadrate and the presence of mineralized periderm representing the conulariids autapomorphies. The clade (Notoconularia (Climacoconus (Paraconularia, Reticulaconularia))) is characterized by the interlaced arrangement of the corner sulcus ornamentation, the angulated corner sulcus morphology and the trochoidal transverse ribs. The alternate arrangement of the external ornamentation of the midline supports the clade (Climacoconus (Paraconularia, Reticulaconularia)). Any synapomorphy support the clade (Paraconularia, Reticulaconularia), being characterized by homoplasies. From the taxonomic point of view, the classical suprageneric groups (Conulariinae, Paraconulariinae and Ctenoconulariinae) recognized in the TIP were not identified. These groups are not phylogenetically valid, since they are supported by symplesiomophies and homoplasies only. Conulariid genera were classified as phylum Cnidaria, class Scyphozoa, order Conulariida and family Conulariidae. The examination of 1450 specimens indicated that Conularia milwaukeensis, C. quichua, C. albertensis, C. distincta, C. crenulata, C. expansa, C. tuberculata, C. acutilirata, Paraconularia ulrichana, P. africana, P. acuminata, P. pulcheria, P. derwentensis, Reticulaconularia baini and Baccaconularia cf. robinsoni yielded morphological features (septa, carina, articulation, arrangement of the corner sulcus ornamentation, external ornamentation in the midline) not previously described in the literature. Additionally, this study also encompassed the systematic review of ingroup members including the taxonomic reinterpretation of Vendoconularia (Ust? Pinega Formation, Proterozoic, Onega River, Russia), Malvinoconularia (Belén Formation, Devonian, Santa Cruz de La Sierra, Bolivia) and Baccaconularia (Saint Lawrence Formation, Upper Cambrian, United States), the redescription of C. milwalkeensis (Little Cedar Formation, Iowa and Milwaukee Formation, Wisconsin, Devonian, United States) and, finally, the description of Teresconularia, a new genus of Ordovician of Argentina.

No description available.

A análise cladística de Conulariidae (Cnidaria) é aqui apresentada, e está fundamentada na hipótese de que os agrupamentos taxonômicos (famílias, subfamílias), propostos no ?Treatise on Invertebrate Paleontology? (TIP), não são filogeneticamente válidos. O estudo apresentado levou em consideração a revisão do material depositado em coleções do Brasil e do exterior e teve como objetivos principais (1) a análise cladística dos conulários, procurando determinar o escopo do grupo e (2) discutir as implicações dos dados obtidos na sistemática de Conulariidae. Ao todo, 17 caracteres foram estabelecidos e descritos para a anatomia externa e interna da teca de conulários, envolvendo 15 táxons para o grupo-interno (Archaeoconularia, Climacoconus, Conularia, Conularina, Ctenoconularia, Eoconularia, Metaconularia, Paraconularia, Pseudoconularia), incluindo 6 gêneros (Teresconularia, Vendoconularia, Baccaconularia, Glyptoconularia, Notoconularia e Reticulaconularia), propostos após a publicação do TIP. Cubozoa, Stauromedusae, Coronatae e Semaeostomeae constituíram o grupo-externo. A análise de parcimônia obteve 124 cladogramas igualmente mais parcimoniosos. A análise de pesagem sucessiva resultou em 3 cladogramas mais parcimoniosos. Os cladogramas resultantes da análise de pesagem sucessiva indicam que os táxons terminais Conularina, Baccaconularia e Glyptoconularia aparecem em diferentes posições. O cladograma de consenso semi-estrito, gerado após a análise de pesagem sucessiva, mostrou-se totalmente resolvido, representando uma das 124 árvores originais encontradas. No cladograma de consenso semi-estrito não havia caracteres suficientes que sustentassem todos os clados pela otimização ACCTRAN ou DELTRAN. Dessa forma, o clado ((Archaeoconularia, Metaconularia) (Conularina (Notoconularia (Climacoconus (Paraconularia, Reticulaconularia)))))) foi colapsado, formando a politomia entre ((Baccaconularia, Glyptoconularia) (Archaeoconularia, Metaconularia) (Conularina (Notoconularia (Climacoconus (Paraconularia, Reticulaconularia))))))), sustentada pela presença de ornamentação externa na região da linha mediana. Os dados mostram que o grupo-interno é monofilético, sustentado pela forma geométrica da teca, em seção transversal, na região oral, quadrada e presença de periderme mineralizada, constituindo as autapomorfias dos conulários. O clado (Notoconularia (Climacoconus (Paraconularia, Reticulaconularia))) é distinguido pela disposição da ornamentação entrelaçada no sulco da aresta, forma angulada do sulco da aresta e cordões do tipo trocoidal. O encontro alternado dos cordões na região da linha mediana caracteriza o clado composto por (Climacoconus (Paraconularia, Reticulaconularia)). O clado (Paraconularia, Reticulaconularia) não apresenta sinapomorfias, sendo sustentado por caracteres homoplásticos. Do ponto de vista taxonômico, não houve a possibilidade de identificação dos agrupamentos (Conulariinae, Paraconulariinae e Ctenoconulariinae) presentes no TIP. Dessa forma, esses não são consistentes, pois não são sustentados por sinapomorfias, mas sim por simplesiomorfias e homoplasias. Os gêneros de conulários analisados foram agrupados no filo Cnidaria, classe Scyphozoa, ordem Conulariida e família Conulariidae. A partir do exame de 1450 exemplares, as espécies Conularia milwaukeensis, C. quíchua, C. albertensis, C. distincta, C. crenulata, C. expansa, C. tuberculata, C. acutilirata, Paraconularia ulrichana, P. africana, P. acuminata, P. pulcheria, P. derwentensis, Reticulaconularia baini e Baccaconularia cf. robinsoni tiveram estruturas morfológicas reconhecidas (septos, carenas, articulação, disposição da ornamentação no sulco da aresta, ornamentação externa na região da linha mediana) não descritas previamente. Em adição, foram realizadas as revisões sistemáticas de membros do grupo-interno, incluindo a reinterpretação de Vendoconularia (Formação Ust? Pinega, Proterozóico, Onega River, Rússia), Malvinoconularia (Formação Belén, Devoniano, Santa Cruz de La Sierra, Bolívia) e Baccaconularia (Formação Saint Lawrence, Cambriano Superior, Estados Unidos), a redescrição sistemática de C. milwalkeensis (Formação Little Cedar, Iowa e Formação Milwaukee, Wisconsin, Devoniano, Estados Unidos) e, finalmente, a descrição de Teresconularia, um novo gênero do Ordoviciano da Argentina. / The Conulariidae (Cnidaria) cladistic analysis is here presented being founded on the hypothesis that the classical suprageneric groups (families and subfamilies) recognized in the ?Treatise on Invertebrate Paleontology? (TIP), are not phylogenetically valid. The study included the revision of fossil material deposited in Brazilian and international scientific collections, having the following objectives (1) the conulariid cladistic analysis to elucidate the taxonomic scope of this group and (2) the discussion of the implications of the cladistic data gathered on Conulariidae systematic. A total of 17 characters were scored for the external and internal thecae morphology of 15 ingroup taxa (Archaeoconularia, Climacoconus, Conularia, Conularina, Ctenoconularia, Eoconularia, Metaconularia, Paraconularia, Pseudoconularia), including 6 genera (Teresconularia, Vendoconularia, Baccaconularia, Glyptoconularia, Notoconularia and Reticulaconularia), proposed after the publication of the TIP. Cubozoa, Stauromedusae, Coronatae and Semaeostomeae constituted the outgroup. Unweighted analysis of the data matrix yielded 124 trees. Successive weighting analysis resulted in 3 trees. The successive weighting trees indicated that the taxa Conularina, Baccaconularia and Glyptoconularia appear in different positions. The semi-strict tree is totally resolved, representing one of the 124 original trees found. In the semi-strict tree not all clades were supported by characters using ACCTRAN or DELTRAN optimizations. The clade ((Archaeoconularia, Metaconularia) (Conularina (Notoconularia (Climacoconus (Paraconularia, Reticulaconularia)))))) was collapsed, forming a politomy among ((Baccaconularia, Glyptoconularia) (Archaeoconularia, Metaconularia) (Conularina (Notoconularia (Climacoconus (Paraconularia, Reticulaconularia))))))), that was supported by the presence of external ornamentation in the midline. The data shows the internal group as monophyletic and is supported by the theca geometry in the oral section quadrate and the presence of mineralized periderm representing the conulariids autapomorphies. The clade (Notoconularia (Climacoconus (Paraconularia, Reticulaconularia))) is characterized by the interlaced arrangement of the corner sulcus ornamentation, the angulated corner sulcus morphology and the trochoidal transverse ribs. The alternate arrangement of the external ornamentation of the midline supports the clade (Climacoconus (Paraconularia, Reticulaconularia)). Any synapomorphy support the clade (Paraconularia, Reticulaconularia), being characterized by homoplasies. From the taxonomic point of view, the classical suprageneric groups (Conulariinae, Paraconulariinae and Ctenoconulariinae) recognized in the TIP were not identified. These groups are not phylogenetically valid, since they are supported by symplesiomophies and homoplasies only. Conulariid genera were classified as phylum Cnidaria, class Scyphozoa, order Conulariida and family Conulariidae. The examination of 1450 specimens indicated that Conularia milwaukeensis, C. quichua, C. albertensis, C. distincta, C. crenulata, C. expansa, C. tuberculata, C. acutilirata, Paraconularia ulrichana, P. africana, P. acuminata, P. pulcheria, P. derwentensis, Reticulaconularia baini and Baccaconularia cf. robinsoni yielded morphological features (septa, carina, articulation, arrangement of the corner sulcus ornamentation, external ornamentation in the midline) not previously described in the literature. Additionally, this study also encompassed the systematic review of ingroup members including the taxonomic reinterpretation of Vendoconularia (Ust? Pinega Formation, Proterozoic, Onega River, Russia), Malvinoconularia (Belén Formation, Devonian, Santa Cruz de La Sierra, Bolivia) and Baccaconularia (Saint Lawrence Formation, Upper Cambrian, United States), the redescription of C. milwalkeensis (Little Cedar Formation, Iowa and Milwaukee Formation, Wisconsin, Devonian, United States) and, finally, the description of Teresconularia, a new genus of Ordovician of Argentina.

O objetivo deste trabalho de pesquisa é o de buscar entender os tempos e eventos que determinaram as grandes mudanças climáticas no Éon Fanerozoico. Técnicas são constituídas, metodologias estabelecidas, e por vezes são aceitas como sendo as verdades científicas. Com as inovações nas técnicas, com o mudar das ciências, mudam as evidências, mudam as verdades, fazendo mudar nossa percepção do passado. Este trabalho apresenta elementos para um debate sobre o clima da Terra no Fanerozoico, estabelecido a partir de pesquisas bibliográficas sobre evidências passadas e atuais. / The goal of this research work is to understand the times and events that determined the great climatic changes in the Phanerozoic Eon. Techniques are constituted, methodologies are established, and are sometimes accepted as scientific truths. With innovations in techniques, with the change of science, change the evidence; change the truths, making change our perception of the past. This paper presents elements for a discussion on the Earth\'s climate in Phanerozoic established from bibliographical research on past and current evidences.

Underlying all applications of sulfur isotope analyses is our understanding of isotope systematics. This dissertation tests some fundamental assumptions and assertions, drawn from equilibrium theory and a diverse body of empirical work on biochemical kinetics, as applied to the multiple sulfur isotope systematics of microbial sulfate reduction. I take a reductionist approach, both in the questions addressed and experimental approaches employed. This allows for a mechanistic, physically consistent interpretation of geological and biological sulfur isotope records. The goal of my work here is to allow interpreters a more biologically, chemically and physically parsimonious framework to decipher the signals coded in modern and ancient sulfur isotope records. / Earth and Planetary Sciences

No description available.

No / The excavation at Cnip, Isle of Lewis, Scotland of the largest, and only known family cemetery from the early Norse period in the Hehrides, provided a unique opportunity to use Sr isotope analysis to examine the origins of people who may have been Norwegian Vikings. Sr isotope analysis permits direct investigation of a person's place of origin rather than indirectly through acquired cultural and artefactual affiliations. Sr isotope data suggest that the Norse group at Cnip was of mixed origins. The majority were consistent with indigenous origins but two individuals, of middle-age and different sex. were immigrants. They were, however, not from Norway but were raised separately, most probably on Tertiary volcanic rocks (e.g. the Inner Hebrides or NE Ireland) or, for the female, on marine carbonate rocks.