Lenhos in situ de coníferas do Triássico Superior, em depósitos de canais fluviais da Formação Caturrita, Faxinal do Soturno, Rio Grande Do Sul, Brasil

Archeomagnetism of Jesuit Missions in South Brazil (1657–1706 AD) and assessment of the South American database

New archeointensity data from South Brazil and the influence of the South Atlantic Anomaly in South America

The first Miocene records of silicified fossil woods from the Mariño Formation, Potrerillos area, Andes Precordillera, Mendoza province, Argentina are described. Rhaphithamnoxylon artabeae gen. et sp. nov. is described as the first fossil wood referable to Verbenaceae from Argentina. This new fossil species is related to extant Rhaphithamnus Miers, sharing the following anatomical features: diffuse porosity, distinct growth ring boundaries, numerous small to very small vessels, commonly in radial multiples, 1–3 seriate rays, and heterocellular and scarce paratracheal axial parenchyma. Rhaphithamnus contains only two extant species: R. spinosus (A.L. Juss.) Moldenke, which occurs in the Valdivian forests of Chile and Argentina, and R. venustus (Philippi) Robinson, which is endemic to the Juan Fernández Islands. Representatives of Verbenaceae are distributed predominantly in the Americas from Patagonia (Argentina) to Canada, and they are inferred to have originated in South America. The fossil wood described herein provides new age and geographical constraints on the raphithanoid lineage within Verbenaceae. Other fossil woods recorded from the Mariño level are retained under open nomenclature, as they possess a combination of mostly solitary broad vessels, and smaller vessels in radial multiples or in clusters, with numerous, vasicentric to confluent axial parenchyma, and heterocellular, high rays. Thus, they have features akin to dicotyledonous lianas or vine-like or small shrub species.

The El Nino impact on Brazil's summer monsoon has not been adequately assessed through seasonal analysis because it shows significant subseasonal variations. In this study, the El Nino influence on the summer monsoon circulation, rainfall, and temperature is analyzed with monthly resolution, using data from a dense network of stations. The expected precipitation percentiles during the monsoon season of El Nino (EN) events are calculated, as well as anomalies of surface temperature and thermodynamic parameters. This information is analyzed jointly with anomaly composites of several circulation parameters. The analysis shows that some precipitation and circulation anomalies, which are consistent and important during part of the season, are smoothed out in a seasonal analysis. There are abrupt changes of anomalies within the summer monsoon season, suggesting the prevalence of regional processes over remote influences during part of the season. The probable role of remote influences and regional processes is assessed. The anomalous heat sources associated with El Nino perturb the Walker and Hadley circulations over South America and generate Rossby wave trains that produce important effects in the subtropics and extratropics. In the early summer monsoon season, remotely produced atmospheric perturbations prevail over Brazil. Anticyclonic low-level anomalies predominate over central-east Brazil, in the Tropics and subtropics, due to the subsidence over the Amazon and to Rossby waves in the subtropics. Easterly moisture inflow from the Atlantic is favored, but diverted toward northern South America (SA) and south Brazil. There are negative precipitation anomalies in north and central-east Brazil and positive ones in south Brazil. These precipitation anomalies are favored by the perturbation in the Walker and Hadley circulation over the east Pacific and South America, and by a Rossby wave train over southern SA that originates in the eastern Pacific. In January, with the enhancement of the continental subtropical heat low by anomalous surface heating during the spring, there is anomalous low-level convergence and cyclonic circulation over southeast Brazil, while at the upper levels anomalies of divergence and anticyclonic circulation prevail. This anomalous circulation directs moisture flux toward central-east Brazil, causing moisture convergence in this region. A favorable thermodynamic structure enhances precipitation over central-east Brazil, the dry anomalies in north Brazil are displaced northward, and the anomalies in south Brazil almost disappear. In February, after the above-normal precipitation of January, the surface temperature anomalies turn negative and the precipitation diminishes in central-east Brazil. There are negative rainfall anomalies in north Brazil and in the South Atlantic convergence zone (SACZ) and positive ones in south Brazil. Influence function analysis shows that while the anomalies of circulation over southeast Brazil in the spring of El Nino years are mostly due to remote influences from the tropical east Pacific, those in January are probably due to local influence. During this month the monsoonlike circulation is enhanced. Simultaneous and lagged correlation analysis of SST and rainfall in central-east Brazil shows that SST anomalies in the Atlantic Ocean off the southeastern coast of Brazil fluctuate on the same timescale as the circulation and precipitation anomalies.

The rainy season in most of Brazil is associated with the summer monsoon regime in South America. The quality of this season is important because it rains little during the rest of the year over most of the country. In this study, the influence of La Nina events on the summer monsoon circulation, rainfall and temperature is analyzed with seasonal and monthly resolution, using data from a dense network of stations, giving a comprehensive view of the impact of these events. The expected precipitation percentiles during the monsoon season of La Nina events are calculated, as well as anomalies of surface temperature and thermodynamic parameters. This information is analyzed jointly with anomaly composites of several circulation parameters. The analysis shows that some anomalies, which are consistent and important during part of the season, are smoothed out in a seasonal analysis. There are abrupt changes of anomalies within the summer monsoon season, suggesting the prevalence of regional processes over remote influences during part of the season. In spring there are positive precipitation anomalies in north and central-east Brazil and negative ones in south Brazil. These precipitation anomalies are favored by the perturbation in the Walker and Hadley circulation over the eastern Pacific and South America, and by perturbations in the rotational circulation over southern South America. Northerly moisture inflow from the Atlantic into northern South America is emphasized and diverted towards the mouth of the Amazon by the low-level cyclonic anomaly north of the equator. In December and January, probably triggered by anomalous surface cooling during the spring, there is an anomalous low-level divergence and an anticyclonic anomaly over southeast Brazil. This anomalous circulation directs moisture flux towards south Brazil, causing moisture convergence in part of this region and part of central-west Brazil. The thermodynamic structure in central-east Brazil does not favor precipitation over this region, and the wet anomalies in north Brazil are displaced northward. The dry anomalies in south Brazil almost disappear and even turn positive. In February, after the strongly below normal precipitation of January, the surface temperature anomalies turn positive over southeast Brazil. The low-level anticyclonic anomaly is much weaker than in January. There are positive rainfall anomalies in north Brazil and in the South Atlantic Convergence Zone, and negative ones return to south Brazil.

The Paleocene-Eocene boundary was a period of transient and intense global warming that had a deep effect on middle and high latitude plant groups. Nevertheless, only scarce early Paleogene paleoclimatic records are known from the South American continental sequences deposited at these latitudes. In this contribution clay mineralogy and paleobotanical analyses (fossil woods and phytoliths) were used as paleoclimate proxies from the lower and middle parts of the Río Chico Group (Golfo San Jorge basin, Patagonia, Argentina). These new data may enable to understand the changing climatic conditions during part of the Paleocene-Eocene transition. In this setting, three clay mineral assemblages were identified: S1 assemblage (smectite) dominates the Peñas Coloradas Formation; S2 assemblage (smectite>kaolinite) occurs in the stratigraphic transition to the Las Flores Formation; and S3 assemblage (kaolinite>smectite) dominates the Las Flores Formation. These trend of change in the detrital clay mineral composition is interpreted as resulting mainly from the changing paleoclimatic conditions that shifted from seasonal warm temperate to tropical affecting the same source area lithology. Moreover, the paleobotanical data suggest that the Early Paleogene vegetation in the Golfo San Jorge basin underwent significant composition and diversity changes, ranging from mixed temperate - subtropical forest to mixed subtropical - tropical, humid forest. The integrated analysis of the clay mineral composition and the palaeobotanical assemblages suggests that, in central Argentinean Patagonia, the Paleocene-Eocene climate changed from temperate warm, humid and highly seasonal precipitation conditions to subtropical-tropical, more continuous year-round rainfall conditions.

The fossil woods identified in the Permian strata of Parana Basin are revised in its validity, based in the original descriptions and proposed names published. Twenty-eight genera and 52 species are confirmed, most represented by nearly complete preserved materials, and few by its tracheidoxyls. Most of the wood material originates from Irati Formation (Middle Permian), which outcrops are located in Sao Paulo state, and a smaller amount is found in Rio Bonito (Lower Permian) and Serra Alta (Upper Permian) formations, from Rio Grande do Sul and Santa Catarina states. According to the rules of the ICBN and the new contributions in the fossil wood descriptions, 47 specific names used to the Permian wood remains could be legitimate by its diagnosis and diagramatic representation. Five species ( Polysolenoxylon bageense , Scleromedulloxylon batoviense , Aracnomedulloxylon gabrielensis , Myelontordoxylon glandulifera and Polysolenoxylon resiniferum ) are rejected in the diagnosis and description of characters presented and deserve a new description due to the unprecedented nature of some of their logs in the basin. Key words: Fossil wood, nomenclature, Permian, Parana Basin, South Brazil.

Tracing back hepatitis B virus genotype D introduction and dissemination in South Brazil

The genus Orthocis Casey is represented by 46 species occurring in insular and continental areas of the World, except for the Antarctic. Three Orthocis species are currently known from South America: the Andean O. elguetai Lopes-Andrade, from Chile; the Neotropical O. apicipennis (Pic) from a single locality in South Brazil; and O. platensis Brèthes from Buenos Aires, Argentina. Orthocis platensis is here redescribed and recorded for the first time from South and Southeast Brazil.

Diverse and rich fossil wood records have been documented from the Mesozoic of Liaoning Province, NE China. The Tiaojishan Formation (mainly distributed in Beipiao, Chaoyang, Fuxin and Jianchang regions) is one of the most significant horizons for the Jurassic petrified wood in Liaoning Province. Previously, wood fossils of this formation were mainly reported in Beipiao and Chaoyang regions, whereas fossil wood record was merely known in Jianchang region. Here we describe new fossil wood specimens from the Tiaojishan Formation in Jianchang County, western Liaoning. Two fossil wood taxa, i.e., Protaxodioxylon jianchangense Tian et Wang sp. nov. and Xenoxylon peidense Zheng et Zhang were recognized on the basis of anatomical features. These fossil wood records add new data for understanding the fossil wood diversity, floral composition and palaeoclimate of the Tiaojishan Formation. The occurrence of Xenoxylon and Protaxodioxylon implies a cool temperate, wet and seasonal climate condition with interannual variations during the Middle to Late Jurassic transition in western Liaoning region.

New record of fossil wood Xenoxylon from the Late Triassic in the Sichuan Basin, southern China and its paleoclimatic implications

The human colonization of the Southeast Plains of South America: Climatic conditions, technological innovations and the peopling of Uruguay and south of Brazil

The taxon Chydorus faviformis, described by Birge from North America in 1893, has been considered to occur also in Asia, Australia, and South America. However, careful study of populations from these regions has revealed that all represent different species, none of which is closely related to C. faviformis. The taxa described here are C. obscurirostris and C. opacus from Australia, C. obscurirostris tasekberae from Malaysia, C. sinensis from China, C.angustirostris from India, and C. parvireticulatus from South America. The taxon in Malaysia differs somewhat from the corresponding taxon in Australia, but cannot be characterized more closely until males and ephippial females become available. The taxa differ among themselves in number of meshes on the shell of parthenogenetic females, surface patterning within the meshes, shape of the rostrum and height of the mesh walls along the edge and near the tip of the rostrum, stoutness and length of the major seta on the inner distal lobe of trunklimb I, shape of the labral plate, and shape and armament of the postabdomen. Ephippial females all have a single resting egg. They differ in the extent of secondary thickenings of the surface network within the shell meshes and in the amount of pigment deposited in the region of the egg locule. Males are most important for separating the taxa, indicating how necessary they are for working out evolutionary similarities and differences. Unfortunately no males of the taxa from Malaysia, India, and South America have been available. For the others, C.faviformis sens. str. is unique in that it is the only taxon in which the male loses its honeycomb (that is, the raised walls of the meshes) on reaching maturity. It also has a sharp pre-anal angle and a marked narrowing of the postabdomen distad from here, which is the pattern typical of species in the Chydorus sphaericus complex. None of the other faviformis-like species share this characteristic. Because of the marked differences in morphology and in geographical distribution of the species in North America and in South America, it is certain that even during the glacial ages, when the northern C. faviformis would have been displaced farthest southward, there was no exchange of either taxon to the other continent. The taxon from Manáos, Brazil listed as C.faviformis in the Birge collection is the C. parvireticulatus reported from much farther south in Brazil and Argentina. In Australia and Asia, except for the uncertain distinctness of the taxon in Malaysia, all the other taxa are markedly separate from each other and hence give no evidence for transfer, as by resting eggs, between continents or even from one region to another on the same continent. All the taxa have been stable in their geographical occurrence for very long periods of time. In addition to the faviformis-like taxa present as distinct species in different regions or on different continents, there are many other species groups of chydorids that have different member species on each continent. One possible explanation of this similarity in gross morphology without any long-distance dispersal of resting eggs to accomplish it is that the various protospecies (corresponding to the species groups) had largely evolved before the original land mass broke up into the present continents and subcontinents. As the distances between the continents increased, the salt-water gaps would come to be impassable barriers to dispersal. Evolution of the isolates would then yield new species, all retaining m any of the features of the protospecies. Each such group from a single protospecies would form the species groups we are now just beginning to recognize.

Composition of Paleocene forests from Antarctica based on fossil wood

The present work introduces the first anatomical and systematic study of a fossil wood found in the Northern Pampa. The diagnostic anatomical features of the fossil wood are common in the Proteaceae family and Roupala genus. This fossil wood can be included within the organ genus Scalarixylon, Pujana. This family is considered a relict group from Gondwana because of its disjunct modern distribution in Australia, Africa, Central and South America, and limited places in Asia and the Pacific Isla. This finding is particularly significant for future paleobiogeography interpretations about this region and for the occurrence of Proteaceae fossil in the Parana Basin over the Pleistocene.