Phylogeny, biogeography and diversification patterns of side-necked turtles (Testudines: Pleurodira)

Pleurodires or side-necked turtles are today restricted to freshwater environments of South America, Africa– Madagascar and Australia, but in the past they were distributed much more broadly, being found also on Eurasia, India and North America, and marine environments. Two hypotheses were proposed to explain this distribution; in the first, vicariance would have shaped the current geographical distribution and, in the second, extinctions constrained a previously widespread distribution. Here, we aim to reconstruct pleurodiran biogeographic history and diversification patterns based on a new phylogenetic hypothesis recovered from the analysis of the largest morphological dataset yet compiled for the lineage, testing which biogeographical process prevailed during its evolutionary history. The resulting topology generally agrees with previous hypotheses of the group and shows that most diversification shifts were related to the exploration of new niches, e.g. littoral or marine radiations. In addition, as other turtles, pleurodires do not seem to have been much affected by either the Cretaceous– Palaeogene or the Eocene–Oligocene mass extinctions. The biogeographic analyses highlight the predominance of both anagenetic and cladogenetic dispersal events and support the importance of transoceanic dispersals as a more common driver of area changes than previously thought, agreeing with previous studies with other non-turtle lineages.Fil: Ferreira, Gabriel S.. Universidade de Sao Paulo; Brasil. Senckenberg Centre For Human Evolution And Palaeoenvironment; Alemania. Universität Tübingen; AlemaniaFil: Bronzati Filho, Mario. Bayerische Staatssammlung für Paläontologie und Geologie; AlemaniaFil: Langer, Max C.. Universidade de Sao Paulo; BrasilFil: Sterli, Juliana. Museo Paleontológico Egidio Feruglio; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Diagnóstico e prognóstico de serviços ambientais de reconstrução de canais de rios na avulsão do Rio Taquari na região do Caronal.

Arrombados e avulsões são fenômenos inerentes a sistemas de rios distributários em lobos ativos de megaleques. No Pantanal, esses fenômenos já aconteceram no passado e o mais recente e de grandes proporções ocorreu na região do Caronal, no Rio Taquari. Este estudo traz novas análises quali-quantitativas da dinâmica espaço-temporal de arrombados no Caronal e da deposição de sedimentos (splay) na avulsão que se estabeleceu na região do Paiaguás. As análises permitiram mapear no tempo as mudanças de surgimento e desaparecimento das arrombados, bem como criar um modelo scale-invariant de previsão indicando que em 2050 o tamanho e o comprimento máximo da área de deposição de sedimentos na avulsão deverão ser respectivamente de 1.258 km2 e 100 km. Portanto, no longo prazo, a canalização do rio Taquari no Paiaguás deverá ser estabelecida caso sejam mantidas as condições ecohidrológicas e dos serviços ambientais presentes

Microbially induced pseudotraces from a Pantanal soda lake, Brazil : Alternative interpretations for Ediacaran simple trails and their limits

Despite the absence of metazoans, structures resembling animal traces are common in a soda lake from the western Brazil Pantanal wetland. Pantanal soda lakes are ecologically extreme environments that preclude complex life, allowing extremophiles to flourish. Direct observation indicates that these structures are pseudotraces, representing groove marks that result from the interaction of wave-transported floating rafts of epibenthic microbial mat fragments with the substrate. Variations in wind/wave direction and intensity result in marks of different size and morphology. The most common pseudotraces are simple and slightly curved, narrow grooves (type 1), whereas others are straight and present raised lateral ridges (type 2). Both are V-shaped in cross section. Type 3 comprises long, sinuous, shallow grooves, displaying internal crescentic laminated infill and U-shaped cross section. The similarity of these pseudotraces to Ediacaran structures usually interpreted as animal trace fossils suggests that care should be exercised in their analysis. A set of criteria is proposed to differentiate microbially induced pseudotraces from trace fossils. Analysis of Ediacaran structures needs to be performed on a case-by-case basis, taking into account morphology, orientation, and preservation style of the structure, sedimentary environment, and presence or absence of microbial mats.Centro de Investigaciones Geológica

Papel das macrófitas aquáticas na sucessão ecológica em sistemas fluvio-lacustres do Pantanal: Lago Uberaba.

As macrófitas aquáticas são importantes componentes do ecossistema úmido que podem promover mudanças e a evolução de paisagens naturais. Os sistemas de informação geográficas ou SIGs auxiliam na identificação de áreas com mudança na cobertura vegetal em planícies inundáveis do Pantanal. O foco deste estudo foi determinar o papel das macrófitas aquáticas flutuantes nas margens do Lago Uberaba situado em um sistema fluvial. O mapeamento temático em imagens georreferenciadas do satélite Landsat no período seco revelou um decréscimo de 21,4% da área de água aberta do lago ao longo de 30 anos (-4,7 km2 /ano). Entretanto, pouca correlação foi encontrada entre a área de água aberta do lago e a cota do rio Paraguai nesse período. A taxa de crescimento da cobertura de macrófitas no lago foi de 1,4 km2 /ano. Os dados sugerem que o crescimento das macrófitas independe da quantidade de chuva e da vazão de água na região. As áreas classificadas como terrestres também tiveram aumento. Para explicar as observações satelitárias históricas, buscou-se inserir nesse contexto o processo de sucessão ecológica vegetal. Nesse processo, plantas r-estrategistas (predomínio aquático) dão lugar a plantas k-estrategistas (predomínio terrestre) em direção ao clímax. Estudos adicionais no Lago Uberaba e outros análogos serão necessários para melhor avaliar essa hipótese formulada para descrever a evolução de processos geomorfológicos dinâmicos na planície de inundação do Pantanal

A summary of the Brazilian Paraná Basin Ordovician

The study of the Ordovician of Paraná Basin culminated on the three-fold lithostratigraphic subdivision of the Rio Ivaí Group as follows: Alto Garças, Iapó and Vila Maria formations. The history of deposition of these rocks is linked to the transition from a marine fluvial environment into the glacial diamictites and shales with dropstones, overlain by post-glacial transgressive shales, siltstones and sandstones. The OrdovicianâSilurian transition is marked by a glacial and an extinction event that impacted the marine diversity of life and the permanence of the first land plants. At least three sections, designated as the sections 1, 2 and 3 below, had their sedimentary facies, taphonomy, organic carbon content and thermal maturation analysed as well as their macro- and microfossil assemblages recognized. All studied sections were productive for macro- and microfossils, although the section 1 has limited occurrence and lower preservation of palynomorphs. The greatest fossil diversity was recovered from the section 2. To date, the diversity recovered from the OrdovicianâSilurian of the Paraná Basin comprises 12 fossil groups, namely ostracods, brachiopods, bivalves, gastropods, cryptospores, fungi, acritarchs, chitinozoans, prasinophyte algae, scole­codonts, a possible graptolite and, more recently, a trilobite of the order Dalmanitidae. 51 species of palynomorphs of terrestrial and marine origin were recognized. This is the highest diversity reported from the glacialâpostglacial transition in the OrdovicianâSilurian boundary interval of Brazil. 18 species of cryptospores, acritarchs and fungi occur in the basal diamictites (the Iapó Formation) as well as the discinoid Kosoidea australis. In the upper part of these diamictites, the palynomorph assemblage comprises 26 taxa, most of which persist also in the postglacial shales. Still, in the shales with dropstones of the Iapó Formation, brachiopods (K. australis, infaunal lingulids, ?Palaeoglossa and rhynchonelliformeans), endemic ostracods such as Satiellina paranaensis and pyritized specimens of a widely common Hirnantian index species Harpabollia harparum occur together with indeterminable ostracod species. At least two different species of bivalve mollusks were also found as well as a gastropod species (Bucanellasp.). Observing the palynomorph assemblage, it was possible to record also chitinozoans restricted to the lowermost portion of the Vila Maria Formation. This part of the formation was observed in the outcrops 2 and 3 and contains postglacial chitinozoan assemblages that are not younger than the earliest Rhuddanian. Some centimeters above this interval but still in the lower part of the Vila Maria Formation, the occurrence of Spinachitina debbajae followed by Spinachitina silurica refer to the Silurian in the Paraná Basin. In the section 1, the recovery of a trilobite thorax configures the oldest record of this group in Brazil and shows that this ancient sea was also thriving with life even after the glaciation-related Hirnantian extinction event