Prehistoric Human Occupations of the Western Venezuelan Llanos

1973 ◽  
Vol 38 (2) ◽  
pp. 182-190 ◽  
Author(s):  
Alberta Zucchi

AbstractRecent archaeological research in the western Venezuelan llanos has provided very old dates related to maize cultivation. The evidence obtained at Mound I, at the site Hato de la Calzada, indicates that these seasonally flooded savannas were occupied from 920 B.C. to A.D. 500 by the Caño del Oso people who practiced hunting, fishing, and maize farming. Around A.D. 500 manioc cultivation and artificial earthworks were introduced in this area. Both elements were probably obtained from the Arauquinoid people who inhabited the Orinoco riverbanks. The available data regarding the antiquity of manioc, based on agricultural systems in seasonally flooded savannas of South America, suggests that such systems developed in the Amazon Basin.

Author(s):  
Mariela C. Castro ◽  
Murilo J. Dahur ◽  
Gabriel S. Ferreira

AbstractDidelphidae is the largest New World radiation of marsupials, and is mostly represented by arboreal, small- to medium-sized taxa that inhabit tropical and/or subtropical forests. The group originated and remained isolated in South America for millions of years, until the formation of the Isthmus of Panama. In this study, we present the first reconstruction of the biogeographic history of Didelphidae including all major clades, based on parametric models and stratified analyses over time. We also compiled all the pre-Quaternary fossil records of the group, and contrasted these data to our biogeographic inferences, as well as to major environmental events that occurred in the South American Cenozoic. Our results indicate the relevance of Amazonia in the early diversification of Didelphidae, including the divergence of the major clades traditionally ranked as subfamilies and tribes. Cladogeneses in other areas started in the late Miocene, an interval of intense shifts, especially in the northern portion of Andes and Amazon Basin. Occupation of other areas continued through the Pliocene, but few were only colonized in Quaternary times. The comparison between the biogeographic inference and the fossil records highlights some further steps towards better understanding the spatiotemporal evolution of the clade. Finally, our results stress that the early history of didelphids is obscured by the lack of Paleogene fossils, which are still to be unearthed from low-latitude deposits of South America.


2013 ◽  
Vol 6 (1) ◽  
pp. 453-494 ◽  
Author(s):  
D. S. Moreira ◽  
S. R. Freitas ◽  
J. P. Bonatti ◽  
L. M. Mercado ◽  
N. M. É. Rosário ◽  
...  

Abstract. This article presents the development of a new numerical system denominated JULES-CCATT-BRAMS, which resulted from the coupling of the JULES surface model to the CCATT-BRAMS atmospheric chemistry model. The performance of this system in relation to several meteorological variables (wind speed at 10 m, air temperature at 2 m, dew point temperature at 2 m, pressure reduced to mean sea level and 6 h accumulated precipitation) and the CO2 concentration above an extensive area of South America is also presented, focusing on the Amazon basin. The evaluations were conducted for two periods, the wet (March) and dry (September) seasons of 2010. The statistics used to perform the evaluation included bias (BIAS) and root mean squared error (RMSE). The errors were calculated in relation to observations at conventional stations in airports and automatic stations. In addition, CO2 concentrations in the first model level were compared with meteorological tower measurements and vertical CO2 profiles were compared with aircraft data. The results of this study show that the JULES model coupled to CCATT-BRAMS provided a significant gain in performance in the evaluated atmospheric fields relative to those simulated by the LEAF (version 3) surface model originally utilized by CCATT-BRAMS. Simulations of CO2 concentrations in Amazonia and a comparison with observations are also discussed and show that the system presents a gain in performance relative to previous studies. Finally, we discuss a wide range of numerical studies integrating coupled atmospheric, land surface and chemistry processes that could be produced with the system described here. Therefore, this work presents to the scientific community a free tool, with good performance in relation to the observed data and re-analyses, able to produce atmospheric simulations/forecasts at different resolutions, for any period of time and in any region of the globe.


2021 ◽  
Author(s):  
Markus Deppner ◽  
Bedartha Goswami

<p>The impact of the El Niño Southern Oscillation (ENSO) on rivers are well known, but most existing studies involving streamflow data are severely limited by data coverage. Time series of gauging stations fade in and out over time, which makes hydrological large scale and long time analysis or studies of rarely occurring extreme events challenging. Here, we use a machine learning approach to infer missing streamflow data based on temporal correlations of stations with missing values to others with data. By using 346 stations, from the “Global Streamflow Indices and Metadata archive” (GSIM), that initially cover the 40 year timespan in conjunction with Gaussian processes we were able to extend our data by estimating missing data for an additional 646 stations, allowing us to include a total of 992 stations. We then investigate the impact of the 6 strongest El Niño (EN) events on rivers in South America between 1960 and 2000. Our analysis shows a strong correlation between ENSO events and extreme river dynamics in the southeast of Brazil, Carribean South America and parts of the Amazon basin. Furthermore we see a peak in the number of stations showing maximum river discharge all over Brazil during the EN of 1982/83 which has been linked to severe floods in the east of Brazil, parts of Uruguay and Paraguay. However EN events in other years with similar intensity did not evoke floods with such magnitude and therefore the additional drivers of the 1982/83  floods need further investigation. By using machine learning methods to infer data for gauging stations with missing data we were able to extend our data by almost three-fold, revealing a possible heavier and spatially larger impact of the 1982/83 EN on South America's hydrology than indicated in literature.</p>


2007 ◽  
Vol 5 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Cristina M. Bührnheim ◽  
Luiz R. Malabarba

Odontostilbe pulchra, previously considered species inquirenda in Cheirodontinae and doubtfully assigned from the río Orinoco basin, is redescribed with the rediscovery of two syntypes. Originally described to the Island of Trinidad, O. pulchra is widespread in Venezuela, the río Orinoco basin, in smaller coastal drainages of northern South America, in the Lake Valencia system, and río Essequibo basin. A punctual occurrence in the upper rio Negro, near southernmost headwaters of the río Orinoco, extends its distribution to the Amazon basin. Additionally, two new species of Odontostilbe from the río Orinoco basin are described.


2018 ◽  
Vol 15 (1) ◽  
pp. 279-295 ◽  
Author(s):  
Corina Buendía ◽  
Axel Kleidon ◽  
Stefano Manzoni ◽  
Björn Reu ◽  
Amilcare Porporato

Abstract. Phosphorus (P) availability decreases with soil age and potentially limits the productivity of ecosystems growing on old and weathered soils. Despite growing on ancient soils, ecosystems of lowland Amazonia are highly productive and are among the most biodiverse on Earth. P eroded and weathered in the Andes is transported by the rivers and deposited in floodplains of the lowland Amazon basin creating hotspots of P fertility. We hypothesize that animals feeding on vegetation and detritus in these hotspots may redistribute P to P-depleted areas, thus contributing to dissipate the P gradient across the landscape. Using a mathematical model, we show that animal-driven spatial redistribution of P from rivers to land and from seasonally flooded to terra firme (upland) ecosystems may sustain the P cycle of Amazonian lowlands. Our results show how P imported to land by terrestrial piscivores in combination with spatial redistribution of herbivores and detritivores can significantly enhance the P content in terra firme ecosystems, thereby highlighting the importance of food webs for the biogeochemical cycling of Amazonia.


2020 ◽  
pp. 391-437
Author(s):  
Hugo Villachica ◽  
Jose E. Silva ◽  
Jose Roberto Peres ◽  
Carlos Magno C. da Rocha

2021 ◽  
Vol 118 (37) ◽  
pp. e2105956118
Author(s):  
Kenneth E. Campbell ◽  
Paul B. O’Sullivan ◽  
John G. Fleagle ◽  
Dorien de Vries ◽  
Erik R. Seiffert

The Santa Rosa fossil locality in eastern Perú produced the first Paleogene vertebrate fauna from the Amazon Basin, including the oldest known monkeys from South America. This diverse paleofauna was originally assigned an Eocene age based largely on the stage of evolution of the site’s caviomorph rodents and marsupials. Here, we present detrital zircon dates that indicate that the maximum composite age of Santa Rosa is 29.6 ± 0.08 Ma (Lower Oligocene), although several zircons from Santa Rosa date to the Upper Oligocene. The first appearance datum for Caviomorpha in South America is purported to be the CTA-27 site in the Contamana region of Perú, which is hypothesized to be ∼41 Ma (Middle Eocene) in age. However, the presence of the same caviomorph species and/or genera at both CTA-27 and at Santa Rosa is now difficult to reconcile with a >11-My age difference. To further test the Middle Eocene age estimate for CTA-27, we ran multiple Bayesian tip-dating analyses of Caviomorpha, treating the ages of all Paleogene species from Perú as unknown. These analyses produced mean age estimates for Santa Rosa that closely approximate the maximum 29.6 ± 0.08 Ma composite date provided by detrital zircons, but predict that CTA-27 is much younger than currently thought (∼30 Ma). We conclude that the ∼41 Ma age proposed for CTA-27 is incorrect, and that there are currently no compelling Eocene records of either rodents or primates in the known fossil record of South America.


Author(s):  
Cameron Jones

While it is certainly true that more academic studies have focused on the North American missions, in terms of their historical impact South American missions were just as important to the frontiers of Spain and Portugal’s American empires. The massive size alone of the frontier region, stretching from the upper reaches of the Amazon basin to the headwaters of the Paraná as well as stretching across the lower Southern Cone, meant numerous missionary enterprises emerged in an attempt to evangelize the peoples who inhabited these regions. While small handfuls of Dominicans, Mercedarians, and Augustinians would engage in such efforts, most missions were established by the Jesuits or Franciscans. Certainly, for the Jesuits, or the Society of Jesus as they are properly known, American missions represented an extension of the Counter-Reformation for which they were created. Starting in the mid-16th century, this relatively new organization, founded in 1534, began in earnest to “reduce” the Indigenous peoples into their missions. These activities, however, abruptly ended when the Jesuits were expelled from both the Portuguese and Spanish empires in 1759 and 1767 respectfully. The much older Franciscan order had extensive experience in popular missions in Europe and was one of the first orders of regular clergy in the Americas. Franciscans, like the Jesuits, engaged in evangelizing activities throughout both North and South America from the colonial period to the present. The expulsion of the Jesuits, however, pushed them further to the forefront of missionizing efforts in the late colonial period. This acceleration of Franciscan missionary activity was aided by the establishment of the Apostolic Institute in 1682. The Institute created a pipeline of missionaries from Spain to come directly to frontier areas with funding from the crown. While this aided missionary efforts throughout South America, particularly in areas abandoned by the Jesuits, it embroiled the missionaries in the politics of the Bourbon reforms and their obsession with limited clerical power. Ultimately, while missionizing efforts continued into the Republican period, their association with the Spanish and Portuguese crowns led to widespread suppression and secularization following independence. The historiographical divide in the field tends to lie between usually older, Eurocentric histories by scholar-clerics which focus on the missionaries themselves, and newer studies carried out by more secular professional historians that examine how Indigenous populations were affected by the inherent imperialism of the missions, though exceptions abound.


2021 ◽  
Author(s):  
Juan Sierra ◽  
Jhan Carlo Espinoza ◽  
Clementine Junquas ◽  
Jan Polcher ◽  
Miguel Saavedra ◽  
...  

<p>The Amazon rainforest is a key component of the climate system and one of the main planetary evapotranspiration sources. Over the entire Amazon basin, strong land-atmosphere feedbacks cause almost one third of the regional rainfall to be transpired by the local rainforest. Maximum precipitation recycling ratio takes place on the southwestern edge of the Amazon basin (a.k.a. Amazon-Andes transition region), an area recognized as the rainiest and biologically richest of the whole watershed. Here, high precipitation rates lead to large values of runoff per unit area providing most of the sediment load to Amazon rivers. As a consequence, the transition region can potentially be very sensitive to Amazonian forest loss. In fact, recent acceleration in deforestation rates has been reported over tropical South America. These sustained land-cover changes can alter the regional water and energy balances, as well as the regional circulation and rainfall patterns. In this sense, the use of regional climate models can help to understand the possible impacts of deforestation on the Amazon-Andes zone.</p><p>This work aims to assess the projected Amazonian deforestation effects on the moisture transport and rainfall behavior over tropical South America and the Amazon-Andes transition region. We perform 10-year austral summer simulations with the Weather Research and Forecasting model (WRF) using 3 one-way nested domains. Our finest domain is located over the south-western part of the basin, comprising two instrumented Andean Valleys (Zongo and Coroico river Valleys). Convective permitting high horizontal resolution (1km) is used over this domain. The outcomes presented here enhance the understanding of biosphere-atmosphere coupling and its deforestation induced disturbances.</p>


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