The morphofunctional design of Montealtosuchus arrudacamposi (Crocodyliformes, Upper Cretaceous) of the Bauru Basin, Brazil

Montealtosuchus arrudacamposi, a Peirosauridae from the Upper Cretaceous of the Bauru Basin, was a Crocodyliformes of terrestrial habits. The fossils analyzed in this study belong to the pectoral girdle (scapula and coracoid) and anterior appendicular skeleton (humerus, radius, ulna, carpals, radiale, ulnale, metacarpals and phalanges). In this study we infer the locomotion habits of M. arrudacamposi. A morphometric, morphofunctional and 3D reconstruction of the elements of the pectoral girdle and the anterior limbs of M. arrudacamposi were performed. For a better understanding of the most plausible pectoral girdle and anterior limb posture, the studied bones were virtually disarticulated and articulated on 3D reconstruction. The herein results obtained indicate the structures present a relatively thin and elongated aspect, thus allowing an interpretation that M. arrudacamposi possessed more slender anterior limbs than living crocodyliforms. This condition allowed for an adducted stance and cursorial habits that would enable movement through terrestrial environments for prey searching

Nanoscale 3D quantitative imaging of 1.88 Ga Gunflint microfossils reveals novel insights into taphonomic and biogenic characters

International audiencePrecambrian cellular remains frequently have simple morphologies, micrometric dimensions and are poorly preserved, imposing severe analytical and interpretational challenges, especially for irrefutable attestations of biogenicity. The 1.88 Ga Gunflint biota is a Precambrian microfossil assemblage with different types and qualities of preservation across its numerous geological localities and provides important insights into the Proterozoic biosphere and taphonomic processes. Here we use synchrotron-based ptychographic X-ray computed tomography to investigate well-preserved carbonaceous microfossils from the Schreiber Beach locality as well as poorly-preserved, iron-replaced fossil filaments from the Mink Mountain locality, Gunflint Formation. 3D nanoscale imaging with contrast based on electron density allowed us to assess the morphology and carbonaceous composition of different specimens and identify the minerals associated with their preservation based on retrieved mass densities. In the Mink Mountain filaments, the identification of mature kerogen and maghemite rather than the ubiquitously described hematite indicates an influence from biogenic organics on the local maturation of iron oxides through diagenesis. This non-destructive 3D approach to microfossil composition at the nanoscale within their geological context represents a powerful approach to assess the taphonomy and biogenicity of challenging or poorly preserved traces of early microbial life, and may be applied effectively to extraterrestrial samples returned from upcoming space missions

Heart Fossilization Is Possible And Informs The Evolution Of Cardiac Outflow Tract In Vertebrates

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Elucidating cardiac evolution has been frustrated by lack of fossils. One celebrated enigma in cardiac evolution involves the transition from a cardiac outflow tract dominated by a multi-valved conus arteriosus in basal actinopterygians, to an outflow tract commanded by the non valved, elastic, bulbus arteriosus in higher actinopterygians. We demonstrate that cardiac preservation is possible in the extinct fish Rhacolepis buccalis from the Brazilian Cretaceous. Using X-ray synchrotron microtomography, we show that Rhacolepis fossils display hearts with a conus arteriosus containing at least five valve rows. This represents a transitional morphology between the primitive, multivalvar, conal condition and the derived, monovalvar, bulbar state of the outflow tract in modern actinopterygians. Our data rescue a long-lost cardiac phenotype (119-113 Ma) and suggest that outflow tract simplification in actinopterygians is compatible with a gradual, rather than a drastic saltation event. Overall, our results demonstrate the feasibility of studying cardiac evolution in fossils.5Coordenacao de Aperfeigoamento de Pessoal de Nivel Superior [01P-03488/2014]Fundacao de Amparo a Pesquisa do Estado de Sao Paulo [2012/05152-0]Conselho Nacional de Desenvolvimento Cientifico e Tecnologico [481983/2013-9]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Evidence for Metabolic Diversity in Meso-Neoproterozoic Stromatolites (Vazante Group, Brazil)

Deciphering the evolution of ecological interactions among the metabolic types during the early diversification of life on Earth is crucial for our understanding of the ancient biosphere. The stromatolites from the genus Conophyton cylindricus represent a datum for the Proterozoic (Meso to Neoproterozoic) on Earth. Their typical conical shape has been considered a result of a competition between microorganisms for space, light and nutrients. Well-preserved records of this genus from the Paleontological Site of Cabeludo , Vazante Group, São Francisco Craton (Southern Brazil) present in situ fossilized biofilms, containing preserved carbonaceous matter. Petrographic and geochemical analyses revealed an alternation between mineral laminae (light grey laminae) and fossilized biofilms (dark grey laminae). The dark grey laminae comprise three different biofilms recording a stratified microstructure of microbial communities. These three biofilms composing the dark grey laminae tend to be organized in a specific pattern that repeats through the stromatolite vertical section. Iron and manganese are distributed differently along the dark and light grey laminae; X-ray absorption and luminescence data showed possible different areas with authigenic iron and iron provided from diagenetic infiltration. Cryptocrystalline apatite in the lowermost biofilms in each dark grey laminae may suggest past metabolic activity of sulfide-oxidizing bacteria. These findings suggest that the microorganisms reached a complex metabolic diversification in order to maintain an equilibrium situation between the three different biofilms along the vertical section of the structures, thus benefiting the whole microbial community. This means that the stromatolites from the Conophyton genus may have formed as a result of a greater complexity of interactions between microorganisms, and not only from competition between photosynthesizers

Chemical and morphological characterization of soft tissues preserved in ichtyoliths of Santana Formation (Araripe Basin) : looking for cardiac fossils

Orientador: José Xavier NetoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências MédicasResumo: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digitalAbstract: The complete Abstract is available with the full electronic digital thesis or dissertationMestradoFarmacologiaMestra em Farmacologi

Imageamento por raios-X em 3D de microfósseis Pré-Cambrianos: avaliando a biogenicidade na nanoescala com Tomografia Pticográfica de Raios-X

Precambrian microfossils are structures difficult to be investigated by means of conventional imaging approaches due to their small size, geochemical composition and relative scarcity that limits the use of destructive methods. One recurrent problem in the study of these earliest life forms relies on attesting their biogenicity given that structures formed abiotically can strongly resemble fossilized cells of simple morphology. The search of novel analytical methods for contributing to the evaluation of these ancient structures if of great importance for the development of the field of Precambrian paleobiology. In this work, the coherent X-ray imaging approach of ptychographic X-ray computed tomography is explored for assessing bona fide microfossils from the Gunflint and Draken Formations, and early Archean controversial structures described as fossil bacteria from the Hoogenoeg and Kromberg Formations of the Barberton Greenstone Belt. The microfossils were imaged non-destructively in 3D with nanometric resolution and quantitative electron density contrast, which allowed the estimation of mass density of the materials. The tomographic images provided information on both the morphology and geochemical composition of the specimens at the nanoscale within a microscale context. From the morphological data, it was possible to distinguish the 3D distribution of kerogenous material, which revealed a novel preservation pattern and traces of taphonomical alterations for filaments of Gunflint Formation, and ultrastructural details preserved in cell walls of specimen from Draken Formation. The mass density quantification provided supporting evidences, such as the discrimination of kerogen maturation states and identification of minerals, providing also a picture of the taphonomical history of the specimens. Based in the biogenicity criteria investigated at the nanoscale, we could not attest the biogenicity of the structures described in the Barberton Greenstone Belt, but we offered new possible interpretations of biological and biotic origins for the formation of these structures. The results represent significative advances for the comprehension of fossilized microorganisms and add important contribution for the assessment of biogenicity through a robust combination of morphological and geochemical 3D information from the nano to the micron-scale.Microfósseis Pré-Cambrianos são estruturas difíceis de serem investigadas por técnicas de imagem convencionais devido ao seu pequeno tamanho, composição geoquímica e por serem relativamente raros no registro geológico, o que limita o uso de técnicas destrutivas. Um problema recorrente no estudo dessas primeiras formas de vida é em se atestar sua biogenicidade uma vez que estruturas formadas abioticamente podem difíceis de serem distinguidas de células fossilizadas de simples morfologia. A busca de novos métodos analíticos para contribuir na avaliação dessas estruturas é de grande importância para o desenvolvimento da área de paleobiologia Pré-Cambriana. Neste trabalho, a técnica de imagem de raios X coerente de Tomografia Pticográfica de Raios X foi explorada para investigar microfósseis das Formações Gunflint e Draken, e estruturas controversas descritas como bactérias fósseis das Formações Hoogenoeg e Kromberg de Barberton Greenstone Belt. Os microfósseis foram imageados em 3D com resolução micrométrica e contraste quantitativo por densidade eletrônica, o que possibilitou a quantificação da densidade das estruturas. As imagens tomográficas forneceram informação sobre a morfologia e composição geoquímica dos espécimes em nano-escala e dentro de um contexto de micro-escala. Os dados morfológicos permitiram distinguir a distribuição 3D de querogênio, os quais revelaram um novo padrão de preservação e traços de alterações tafonômicas para espécimes da Formação Gunflint, e detalhes de organização ultra-estrutural preservados em paredes celulares de espécime da Formação Draken. A quantificação de densidade forneceu evidências complementares, como a discriminação do estado de maturação do querogênio e identificação de minerais, fornecendo também uma visão da história tafonômica dos espécimes. Baseados nos critérios de biogenicidade em nanoescala, não foi possível atestar a biogenicidade das estruturas de Barberton Greenstone Belt, mas novas possíveis interpretações de origem biológica e abiótica para essas estruturas foram levantadas. Os resultados obtidos fornecem avanços significativos na compreensão de micro-organismos fósseis e adiciona uma importante contribuição para a investigação da biogenicidade através de uma robusta combinação de informação morfológica e geoquímica em 3D

Un point sur... : Lumière sur les débuts de la vie

National audienc

Signaling Through Retinoic Acid Receptors In Cardiac Development: Doing The Right Things At The Right Times

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Retinoic acid (RA) is a terpenoid that is synthesized from vitamin A/retinol (ROL) and binds to the nuclear receptors retinoic acid receptor (RAR)/retinoid X receptor (RXR) to control multiple developmental processes in vertebrates. The available clinical and experimental data provide uncontested evidence for the pleiotropic roles of RA signaling in development of multiple embryonic structures and organs such eyes, central nervous system, gonads, lungs and heart. The development of any of these above-mentioned embryonic organ systems can be effectively utilized to showcase the many strategies utilized by RA signaling. However, it is very likely that the strategies employed to transfer RA signals during cardiac development comprise the majority of the relevant and sophisticated ways through which retinoid signals can be conveyed in a complex biological system. Here, we provide the reader with arguments indicating that RA signaling is exquisitely regulated according to specific phases of cardiac development and that RA signaling itself is one of the major regulators of the timing of cardiac morphogenesis and differentiation. We will focus on the role of signaling by RA receptors (RARs) in early phases of heart development. This article is part of a Special Issue entitled: Nuclear receptors in animal development (C) 2014 Elsevier B.V. All rights reserved.1849294111Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [2011/15273-7, 2012/14859-0, 2013/12008-6]CNPq [481983/2013-9

Signaling through retinoic acid receptors in cardiac development: Doing the right things at the right times

Retinoic acid (RA) is a terpenoid that is synthesized from vitamin A/retinol (ROL) and binds to the nuclear receptors retinoic acid receptor (RAR)/retinoid X receptor (RXR) to control multiple developmental processes in vertebrates. The available clinical and experimental data provide uncontested evidence for the pleiotropic roles of RA signaling in development of multiple embryonic structures and organs such eyes, central nervous system, gonads, lungs and heart. The development of any of these above-mentioned embryonic organ systems can be effectively utilized to showcase the many strategies utilized by RA signaling. However, it is very likely that the strategies employed to transfer RA signals during cardiac development comprise the majority of the relevant and sophisticated ways through which retinoid signals can be conveyed in a complex biological system. Here, we provide the reader with arguments indicating that RA signaling is exquisitely regulated according to specific phases of cardiac development and that RA signaling itself is one of the major regulators of the timing of cardiac morphogenesis and differentiation. We will focus on the role of signaling by RA receptors (RARs) in early phases of heart development1849294111CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP481983/2013-92011/15273-7; 2012/14859-0; 2013/12008-