Upper Pleistocene deposits of the Comprida Island (São Paulo State) dated by thermoluminescence method

ABSTRACT The Cananéia (Upper Pleistocene) and the Comprida Island (Holocene) formations, outcropping in the Comprida island (SP) have been mapped using geomorphological and lithological criteria. Only one sample of the Cananéia Formation, collected in the homonymous island in front of the Comprida Island, was beyond the limit of the standard radiocarbon method. But since the publication of the geological map of the area in 1978, there has been some doubt on the real occurrence of Pleistocene deposits in southern extremity of Comprida Island. This paper deals with the results of thermoluminescence (TL) ages of eight samples from Comprida Island, which corroborate the Pleistocene age assumed during mapping surveys of these deposits. On the other hand, possible interpretations of the obtained ages, in relation to their depositional environments and related northern hemisphere Quaternary glaciations, are presented

Cretacic pedogenesis and red beds formation in the Minas Gerais triangle

Orientador: Francisco Sergio Bernardes LadeiraDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de GeociênciasResumo: A Formação Marília (Maastrichtiano) ocupa o topo da coluna estratigráfica da Bacia Bauru e vem sendo objeto de consideráveis estudos ao longo das últimas décadas. Esta formação aflora em diferentes estados da porção centro-sul do território nacional e tem como característica a presença de diversos paleossolos intercalados com as rochas sedimentares. Este estudo esta centrado principalmente nos paleossolos (e seus materiais parentais) existentes em afloramentos localizados no oeste de Minas Gerais (Triângulo Mineiro), entre os municípios de Campina Verde e Gurinhatã. A sedimentação varia entre eólica e aluvial nos diferentes afloramentos, sendo que praticamente a totalidade destes é de coloração vermelha, o que os caracteriza como Red beds. A coloração avermelhada se deve a fina camada de hematita que recobre completamente os grãos das rochas e dos paleossolos, sendo que nos paleossolos os poros são preenchidos por argila iluvial e sedimentada na forma de ferriargilãs, muitas vezes com marcas de dessecação. Estas características evidenciam a presença de água no ambiente e o processo de evapotranspiração que se deu no local. O processo de iluviação da argila formada nos paleossolos é então o responsável por cobrir os grãos dos arenitos com a fina camada de hematita que colore os Red Beds da Formação Marília na regiãoAbstract: The Marília Formation (Maastrichtian) occupies the top of the Bauru Basin estratigraphic column and it has been the subject of considerable studies over the past decades. This formation outcrops in different states of the Brazil¿s south-central portion and its main characteristic is then presence of many interleaved paleosols with sedimentary rocks. This study is about mainly the paleosols (and their parent meterials) contained in outcrops located in the west region of Minas Gerais (this region is called "Triângulo Mineiro"), between the cities of Campina Verde and Gurinhatã. Sedimentation ranges from eolic and alluvial in different outcrops, and almost all of them presents red color, which characterizes them as Red beds. The red color is due to the fine hematite layer that covers the rock and paleosol grains, wherein the paleosol pores are filled by iluvial clay and sedimentated as cutans, often with dissection brands. The characteristics show the water presence on the environment and the evapotranspiration process that has occurred on this place. The iluvial process of the clay formed in paleosols is responsible for the covering of the sandstone grains with the fine hematite layer that colors the Red beds of the Marília Formation in that regionMestradoAnálise Ambiental e Dinâmica TerritorialMestre em Geografi

The last dinosaurs of Brazil: The Bauru Group and its implications for the end-Cretaceous mass extinction

ABSTRACT The non-avian dinosaurs died out at the end of the Cretaceous, ~66 million years ago, after an asteroid impact. The prevailing hypothesis is that the effects of the impact suddenly killed the dinosaurs, but the poor fossil record of latest Cretaceous (Campanian-Maastrichtian) dinosaurs from outside Laurasia (and even more particularly, North America) makes it difficult to test specific extinction scenarios. Over the past few decades, a wealth of new discoveries from the Bauru Group of Brazil has revealed a unique window into the evolution of terminal Cretaceous dinosaurs from the southern continents. We review this record and demonstrate that there was a diversity of dinosaurs, of varying body sizes, diets, and ecological roles, that survived to the very end of the Cretaceous (Maastrichtian: 72-66 million years ago) in Brazil, including a core fauna of titanosaurian sauropods and abelisaurid and carcharodontosaurid theropods, along with a variety of small-to-mid-sized theropods. We argue that this pattern best fits the hypothesis that southern dinosaurs, like their northern counterparts, were still diversifying and occupying prominent roles in their ecosystems before the asteroid suddenly caused their extinction. However, this hypothesis remains to be tested with more refined paleontological and geochronological data, and we give suggestions for future work

Pedodiagenetic Characterization of Cretaceous Paleosols in Southwest Minas Gerais, Brazil

The influence of post-burial geological processes on preserving pedogenic properties has great importance in identifying ancient paleosols both in the field and in a laboratory. However there are not many publications that focus on characterizing paleosol diagenesis. As temperature and pressure progressively increase, evidence of pedogenesis is modified and destroyed, hindering paleoenvironment characterization and interpretation. This paper discusses diagenetic evidence and its relation to strictly pedogenic features, like structure, cements, nodules, and neoformation of clay minerals using the carbonate paleosols of the Marilia Formation in the upper unit of the Bauru Basin as a case study. Despite the long geotectonic and thermal history of the Marilia Fomation, paleosols bring us pedogenic evidence that can undergo micromorphological analyses, such as cementation, clay illuviation, bioturbation, and ped structures. The results of analyses in 25 paleopedogenic horizons indicate that the paleotopographic features were responsible for distribution of the diagenetic processes and preservation of the paleosol properties. The maturity of those paleosols controls lithification. In mature paleosols that developed in more stable portions of the landscape, characteristics such as carbonate cementation and development of pedogenic structures are the main factors that inhibit diagenesis. However diagenetic processes that influence poorly-developed paleosols are controlled by depositional characteristics and by changes in the water table, enabling more advanced diagenetic processes, compared to mature paleosols.The influence of post-burial geological processes on preserving pedogenic properties has great importance in identifying ancient paleosols both in the field and in a laboratory. However there are not many publications that focus on characterizing paleosol diagenesis. As temperature and pressure progressively increase, evidence of pedogenesis is modified and destroyed, hindering paleoenvironment characterization and interpretation. This paper discusses diagenetic evidence and its relation to strictly pedogenic features, like structure, cements, nodules, and neoformation of clay minerals using the carbonate paleosols of the Marília Formation in the upper unit of the Bauru Basin as a case study. Despite the long geotectonic and thermal history of the Marília Fomation, paleosols bring us pedogenic evidence that can undergo micromorphological analyses, such as cementation, clay illuviation, bioturbation, and ped structures. The results of analyses in 25 paleopedogenic horizons indicate that the paleotopographic features were responsible for distribution of the diagenetic processes and preservation of the paleosol properties. The maturity of those paleosols controls lithification. In mature paleosols that developed in more stable portions of the landscape, characteristics such as carbonate cementation and development of pedogenic structures are the main factors that inhibit diagenesis. However diagenetic processes that influence poorly-developed paleosols are controlled by depositional characteristics and by changes in the water table, enabling more advanced diagenetic processes, compared to mature paleosols4111

Um Método eficiente para determinar a densidade de venação nas Glossopteris e suas aplicações

Folhas do tipo Glossopteris correspondem ao elemento florístico mais abundante da flora do Gondwana, sendo registradas durante todo o Permiano. Esse foi um período de extremas mudanças climáticas globais, as quais foram capazes de afetar as formas de vida existentes, incluindo as plantas. Nesse contexto, algumas feições foliares são notavelmente sensíveis a variações como essas, sendo, portanto, úteis na reconstrução de paleoambientes. Por esse motivo, os traços funcionais das folhas Glossopteris têm potencial em identificar mudanças ambientais em uma ampla área geográfica por um longo intervalo de tempo. A vascularização foliar possui características especialmente adaptáveis, porém ainda pouco exploradas, principalmente em se tratando de fósseis. Pode-se destacar a densidade de venação, que é calculável e altamente variável, mas muitas vezes considerada uma feição demorada em se quantificar. Uma forma de tornar esse processo mais rápido é através de uma estimativa precisa, embora, até então, nenhum modelo tenha sido formalmente selecionado ou validado para esse tipo de folha. Sendo assim, um modelo linear composto por três preditores foi selecionado e validado por técnicas estatísticas rigorosas, o qual foi treinado com base em 228 dados de folhas fósseis provenientes de diversas bacias e intervalos do Gondwana. Esse modelo permitiu a obtenção de densidades de venação médias para as associações fitofossilíferas compostas por Glossopteris, e teve um erro-padrão de 1,87 cm-1. Além disso, os dados adquiridos distinguiram significativamente as folhas produzidas em ecossistemas úmidos daquelas encontradas nos mais áridos, seguindo um padrão semelhante ao das plantas modernas. Entretanto, dados que contemplem mais sítios fitofossilíferos e intervalos de tempo mais precisos devem ser acrescentados, analisados e comparados, para determinar exatamente como os parâmetros ambientais afetaram a arquitetura vascular foliar das glossopterídeas.Glossopteris-type leaves are the most abundant floristic element of the Gondwana flora, being recorded throughout the Permian. This was a period of extreme global climate changes, which was able to affect existing living forms, including plants. In this context, leaf traces are remarkably sensitive to variations like this, and are therefore useful in the reconstruction of paleoenvironments. For this reason, the functional traits of Glossopteris leaves have the potential to identify environmental changes over a wide geographic area in a long period of time. Leaf vascularization has especially adaptable characteristics, but still underutilized, especially when dealing with fossils. The venation density can be highlighted, since it is calculable and highly variable, but often considered time-consuming to quantify. A way to make this process faster is through an accurate estimation, although no model has been formally selected or validated for this type of leaf so far. Therefore, a linear model composed of three predictors was selected and validated by rigorous statistical techniques, which was trained with 228 data of leaf fossils from different Gondwanan basins and time intervals. This model allowed obtaining mean venation densities for phytofossiliferous associations composed of Glossopteris, and had a standard error of 1.87 cm-1. Furthermore, the data acquired significantly distinguished between leaves produced in wet and dry ecosystems, following a pattern similar to modern plants. However, data covering more phytofossiliferous sites and shorter time spans must be added, analyzed and compared to determine exactly how the environmental parameters affected the leaf vascular architecture of glossopterids

The fate of Holoregmia, a monospecific genus endemic to the Brazilian Caatinga, under different future climate scenarios

Background and aims – Climatic fluctuations during the Pleistocene altered the distribution of many species and even entire biomes, allowing some species to increase their range while others underwent reductions. Recent and ongoing anthropogenic climate change is altering climatic patterns very rapidly and is likely to impact species’ distributions over shorter timescales than previous natural fluctuations. Therefore, we aimed to understand how Pleistocene and Holocene climatic fluctuations might have shaped the current distribution of Holoregmia and explore its expected distribution under future climate scenarios. Material and methods – We modelled the potential distribution of Holoregmia viscida (Martyniaceae), a monospecific plant genus endemic to the semi-arid Caatinga Domain in Brazil. We used an ensemble approach to model suitable areas for Holoregmia under present conditions, Paleoclimatic scenarios, and global warming scenarios in 2050 and 2090. Key results – Holocene climates in most Caatinga were too humid for Holoregmia, which restricted its suitable areas to the southern Caatinga, similar to its current distribution. However, under global warming scenarios, the Caatinga is expected to become too dry for this lineage, resulting in a steady decline in the area suitable for Holoregmia and even its possible extinction under the most pessimistic scenario modelled. Conclusion – The predicted extinction of the ancient and highly specialized Holoregmia viscida highlights the possible consequences of climate change for some species of endemic Caatinga flora. Invaluable phylogenetic diversity may be lost in the coming decades, representing millions of years of unique evolutionary history and consequent loss of evolutionary potential to adapt to future environmental changes in semi-arid environments

Variabilidade genética, demografia, história populacional e comportamento em populações de Sapajus libidinosus

Macacos-prego da espécie Sapajus libidinosus são amplamente conhecidos pelo uso regular de ferramentas nos biomas brasileiros do Cerrado e da Caatinga. Os principais relatos de uso de ferramentas por S. libidinosus provêm do Parque Nacional Serra da Capivara (SCNP), Piauí, Brasil. Dados arqueológicos mostram que eles utilizam ferramentas para acessar recursos alimentícios há ~3.000 anos, o que denota continuidade no tempo, indicando a existência de uma cultura autóctone adaptativa estável. Além disso, S. libidinosus que vivem em cativeiro e em ambientes semilivres, como os do Parque Ecológico do Tietê (TEP), também são conhecidos por usarem ferramentas. Neste trabalho, sequenciamos o gene mitocondrial CYTB de S. libidinosus (N = 40) e de outras espécies para identificar a relação filogenética de S. libidinosus com outros macacos da parvordem Platyrrhini (macacos do Novo Mundo, ou NWMs, do inglês New World Monkeys). Além disso, identificamos a variabilidade genética desta espécie em relação à região codificadora de genes do sistema oxitocinérgico, modulador particularmente de comportamentos complexos e fisiológicos relacionados a reprodução. Nós relatamos pela primeira vez a variante de OXT para outras 20 espécies de NWMs, buscando avançar o conhecimento sobre a extensão da variabilidade desse importante sistema em primatas. A análise do CYTB revelou que os indivíduos de S. libidinosus do SCNP e TEP aparecem na árvore filogenética na posição esperada em relação a outros primatas, mais próximos de Sapajus flavius. Para a população de S. libidinosus do SCNP, as análises Median Joining Network e Bayesian Skyline Plot, e os testes D de Tajima e Fs de Fu indicam uma relativamente recente expansão demográfica (<10.000 anos atrás); enquanto para a população do TEP foi observado um leve declínio no tamanho efetivo da população, com nenhuma indicação de reversão em épocas mais recentes condizentes com a criação do Parque, de acordo com a análise de Bayesian Skyline Plot. Dados do CYTB no TEP não indicaram híbridos com outras espécies do gênero Sapajus, porém, devido à natureza da herança mitocondrial, esse fenômeno não pode ser descartado quando há cruzamentos assimétricos. Devido ao fato de que o desenvolvimento da cultura no SCNP coincide com o intervalo de tempo em que o clima semiárido na Caatinga se estabeleceu (6.000-2.000 mil anos), bem como com a expansão populacional, mediado pelas fêmeas, sugerimos que esses eventos possam estar relacionados, embora a exata razão do gatilho seletivo, que levou a 9 inovação e ao estabelecimento da cultura, ainda seja controversa. A espécie S. libidinosus apresenta a variante funcional Pro8OXT, que está associada ao cuidado parental masculino direto, bem como a monogamia social nos NWMs. Os machos de S. libidinosus não cuidam diretamente da prole, mas são reconhecidamente tolerantes com os infantes que se aproximam, o que favorece o aprendizado social e a transmissão cultural do uso de ferramentas ao longo das gerações. Quanto aos receptores, merece destaque que na posição 62 de AVPR1b (importante mediador no controle da agressividade, ansiedade e estresse) há variabilidade interespecífica e intraespecífica, indicando polimorfismo populacional pelo menos na população de S. libidinosus do SCNP. Sapajus libidinosus apresenta também uma deleção dos aminoácidos 245 a 248, característica do clado Platyrrhini, mas somente estudos adicionais poderão indicar se as variações encontr Sapajus libidinosus apresenta também uma deleção dos aminoácidos 245 a 248, característica do clado Platyrrhini, mas somente estudos adicionais poderão indicar se as variações encontradas no receptor AVPR1b são funcionais e adaptativas. Nossos dados, embora preliminares, fornecem o primeiro relato da variabilidade genética e história demográfica das populações de S. libidinosus do Parque Nacional Serra da Capivara e do Parque Ecológico do Tietê, revelando aspectos até então desconhecidos dessa espécie, fascinante também por sua cultura.Capuchin monkeys of the species Sapajus libidinosus are widely known for their regular use of tools in the Brazilian Cerrado and Caatinga biomes. The main reports of tool use by S. libidinosus come from the Serra da Capivara National Park (SCNP), Piauí, Brazil. Archaeological data show that they have used tools to access food resources for ~ 3,000 years, which denotes continuity in time, indicating the existence of a stable native and adaptive culture. Besides, S. libidinosus that live in captivity and semi-free environments, such as the Tietê Ecological Park (TEP), are also known for exhibiting the use of tools. In this work, we sequenced the mitochondrial gene CYTB from S. libidinosus (N = 40) and from other species to identify the phylogenetic relationship of them with other monkeys of the Platyrrhini parvordem (or New World monkeys, NWMs). Also, we identified the genetic variability of this species about the coding region of the oxytocinergic system genes, which modulates particularly complex and physiological behaviors related to reproduction. We reported for the first time the OXT variant present in another 20 species of NWMs, seeking to advance knowledge about the extent of variability of this critical system in primates. The analysis of CYTB revealed that the individuals S. libidinosus from SCNP and TEP appear in the phylogenetic tree in the expected position concerning other primates, closer to Sapajus flavius. For the SCNP, S. libidinosus population, the Median Joining Network and Bayesian Skyline Plot analyzes, and the Tajima and Fs de Fu tests, indicate a relatively recent demographic expansion (<10,000 years ago). For the TEP, a small decline in the female effective population size was observed, with no indication of a reversal in this tendency in the most recent times consistent with the creation of the Park, according to the analysis of the Bayesian Skyline Plot. CYTB data in the TEP did not indicate hybrids with other species of the genus Sapajus; however, due to the nature of the mitochondrial inheritance, this phenomenon cannot be ruled out when there are asymmetric intercrosses. Because the development of culture in the SCNP coincides with the time interval in which the semi-arid climate in the Caatinga was established (6,000-2,000 years ago), as well as the population expansion, mediated by females, we suggest that these events can be related. However, the exact reason for the selective trigger, which led to innovation and the establishment of culture, is still controversial. The species S. libidinosus presents the functional variant Pro8OXT, which is 11 associated with direct male parental care, as well as social monogamy in NWMs. Males of S. libidinosus do not directly care for their offspring but are known to be tolerant of approaching infants, which favors social learning and the cultural transmission of the use of tools over the generations. As for the receptors, it is worth mentioning that at position 62 of the AVPR1b (important mediator in the control of aggression, anxiety, and stress), there is inter-specific and intra-specific variability, indicating polymorphism at least in the population of S. libidinosus from SCNP. Sapajus libidinosus also has a deletion of amino acids 245 to 248, characteristic of the Platyrrhini clade. Still, only additional studies will be able to indicate whether these variations in the AVPR1b receptor are functional and adaptive. Our data, although preliminary, provide the first account of the genetic variability and demographic history of the populations of S. libidinosus in the Serra da Capivara National Park and the Tietê Ecological Park, revealing aspects previously unknown of this species, also fascinating for its culture