Silurian-Early Devonian ostracodes from South America (Argentina, Bolivia): Preliminary investigations

1995 ◽  
Vol 69 (4) ◽  
pp. 752-772 ◽  
Author(s):  
J. M. C. Vannier ◽  
P. R. Racheboeuf ◽  
J. L. Benedetto
Keyword(s):  
South America ◽  
Lower Devonian ◽  
San Juan ◽  
South American ◽  
Additional Material ◽  
Lower Paleozoic ◽  
Early Devonian ◽  
The North ◽  
Lower Ordovician ◽  
South American Continent

Ostracodes are described from the “Cerro del Fuerte Section” and neighboring localities, all in the Precordillera de San Juan (northern Argentina, San Juan Province), and from sparse faunas in Bolivia (Chuquisaca, Tarabuco Province). Additional material comes from the collection of Thomas (1905). This preliminary study gives the first detailed description of ostracode assemblages in the Upper Silurian and Lower Devonian of the South American continent. Records of other abundant lower Paleozoic (Lower Ordovician to Lower Devonian) ostracodes in Argentina, Bolivia, Brazil, Peru, and Venezuela are also reviewed. Twelve different species, belonging to Palaeocopa (Beyrichiacea and Primitiopsacea) and to Binodicopa and Podocopa (Healdiacea, Thlip-suracea, Cypridacea) are described and a new genus is established (Australobollia n. gen.). Ostracode distribution at Cerro del Fuerte attests to the presence of the Siluro-Devonian boundary within the upper Los Espejos Formation and confirms recent stratigraphical attributions mainly based on conodonts and brachiopods (Benedetto et al., 1992). The beyrichiacean Hemsiella indicates a late Ludlow to Pridolian age for the lower part of upper Los Espejos Formation. The non-palaeocope “Thlipsurella-Phanasymmetria-Ranapeltis” assemblage found in the uppermost part of the formation indicates an Early Devonian (Lochkovian) age. The present study reveals the existence of faunal links at genus (Silurian) and probably species (Early Devonian) level between South America (Argentina, Bolivia), Laurentia, Avalonia-Baltica, and northern Gondwana. For example, close affinities (e.g., Ranapeltis sp. aff. rowlandi and Thlipsurella sp. aff. ellipsoclefta) exist between the uppermost Los Espejos Formation (Argentina) and contemporaneous horizons in the North American Mid-Continent (e.g., Haragan Formation, Oklahoma; Shriver Formation, Pennsylvania). Two types of ostracode assemblages, “beyrichiacean-dominated” and “thlipsuracean-bairdiacean-cypridacean dominated,” are recognized in the Late Silurian–Early Devonian of Argentina and discussed relative to other assemblages known in Laurentia, Avalonia-Baltica, and northern Gondwana. Their paleoecological significance in relation to marine bathymetry is addressed.

scholarly journals Multiple incursion pathways for Helicoverpa armigera in Brazil show its genetic diversity spreading in a connected world

2019 ◽  
Author(s):  
Jonas A. Arnemann ◽  
Stephen H. Roxburgh ◽  
Tom Walsh ◽  
Jerson V.C. Guedes ◽  
Karl H.J. Gordon ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Gene Flow ◽  
South America ◽  
New World ◽  
Flow Patterns ◽  
South American ◽  
Southern Brazil ◽  
American Continent ◽  
Central Brazil ◽  
South American Continent

AbstractThe Old World cotton bollworm Helicoverpa armigera was first detected in Brazil with subsequent reports from Paraguay, Argentina, Bolivia, and Uruguay. This pattern suggests that the H. armigera spread across the South American continent following incursions into northern/central Brazil, however, this hypothesis has not been tested. Here we compare northern and central Brazilian H. armigera mtDNA COI haplotypes with those from southern Brazil, Uruguay, Argentina, and Paraguay. We infer spatial genetic and gene flow patterns of this dispersive pest in the agricultural landscape of South America. We show that the spatial distribution of H. armigera mtDNA haplotypes and its inferred gene flow patterns in the southwestern region of South America exhibited signatures inconsistent with a single incursion hypothesis. Simulations on spatial distribution patterns show that the detection of rare and/or the absence of dominant mtDNA haplotypes in southern H. armigera populations are inconsistent with genetic signatures observed in northern and central Brazil. Incursions of H. armigera into the New World are therefore likely to have involved independent events in northern/central Brazil, and southern Brazil/Uruguay-Argentina-Paraguay. This study demonstrates the significant biosecurity challenges facing the South American continent, and highlights alternate pathways for introductions of alien species into the New World.

South American Missions

2021 ◽  
Author(s):  
Cameron Jones
Keyword(s):  
South America ◽  
Amazon Basin ◽  
Colonial Period ◽  
Indigenous Populations ◽  
South American ◽  
Extensive Experience ◽  
Republican Period ◽  
The North ◽  
Bourbon Reforms ◽  
Franciscan Order

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.

scholarly journals Multiple incursion pathways for Helicoverpa armigera in Brazil show its genetic diversity spreading in a connected world

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jonas Andre Arnemann ◽  
Stephen Roxburgh ◽  
Tom Walsh ◽  
Jerson Guedes ◽  
Karl Gordon ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Gene Flow ◽  
South America ◽  
New World ◽  
Flow Patterns ◽  
South American ◽  
Southern Brazil ◽  
American Continent ◽  
Central Brazil ◽  
South American Continent

AbstractThe Old World cotton bollworm Helicoverpa armigera was first detected in Brazil with subsequent reports from Paraguay, Argentina, Bolivia, and Uruguay. This pattern suggests that the H. armigera spread across the South American continent following incursions into northern/central Brazil, however, this hypothesis has not been tested. Here we compare northern and central Brazilian H. armigera mtDNA COI haplotypes with those from southern Brazil, Uruguay, Argentina, and Paraguay. We infer spatial genetic and gene flow patterns of this dispersive pest in the agricultural landscape of South America. We show that the spatial distribution of H. armigera mtDNA haplotypes and its inferred gene flow patterns in the southwestern region of South America exhibited signatures inconsistent with a single incursion hypothesis. Simulations on spatial distribution patterns show that the detection of rare and/or the absence of dominant mtDNA haplotypes in southern H. armigera populations are inconsistent with genetic signatures observed in northern and central Brazil. Incursions of H. armigera into the New World are therefore likely to have involved independent events in northern/central Brazil, and southern Brazil/Uruguay-Argentina-Paraguay. This study demonstrates the significant biosecurity challenges facing the South American continent, and highlights alternate pathways for introductions of alien species into the New World.

Évolution paléogéographique de la marge nord-ouest de l'Afrique du Cambrien à la fin du Carbonifère (du Maroc au Libéria)

1991 ◽  
Vol 28 (7) ◽  
pp. 1121-1130 ◽  
Author(s):  
Michel Villeneuve ◽  
Jean-Jacques Cornée
Keyword(s):  
West African ◽  
The West ◽  
Lower Paleozoic ◽  
West African Craton ◽  
Middle Cambrian ◽  
Early Devonian ◽  
Middle Ordovician ◽  
The North ◽  
Marine Platform ◽  
General Regression

Paleogeographic reconstructions of Paleozoic time are presented for the northwest margin of the West-African Craton. An extensional regime and a marine transgression were dominant during the Early Cambrian. During the Middle Cambrian, the Rokélides orogen was responsible for the sea regression to the south, while the proto-Atlantic opening was active to the north of the Reguibat shield. A large stable marine platform was present during Early and Middle Ordovician. A general regression and the formation of the West-African Inlandsis took place during the Late Ordovician. During Silurian time, this sea transgressed over most of the African platform. Incipient Hercynian deformations during the Early Devonian produced horsts and grabens in Morocco. At the end of the Devonian and the beginning of the Carboniferous, the sea was restricted to isolated basins and tectonic trenches. Collision between West Africa and North America during the Late Carboniferous transformed the Lower Paleozoic margin into an Hercynian orogenic belt, whose structure is controlled by the presence of crustal blocks, generated as early as the Cambrian, and probably reflecting, in turn, older Panafrican zones of weakness. [Translated by the Journal]

The last pteraspids (Vertebrata, Heterostraci): new material from the Middle Devonian of Alberta and Idaho

2020 ◽  
Vol 94 (4) ◽  
pp. 758-772
Author(s):  
David K. Elliott ◽  
Linda S. Lassiter ◽  
Kathryn E. Geyer
Keyword(s):  
Middle Devonian ◽  
New Genus ◽  
New Combination ◽  
Additional Material ◽  
Lower Paleozoic ◽  
Early Devonian ◽  
Red Sandstone ◽  
Large Channel ◽  
New Material ◽  
Paleozoic Rocks

AbstractThis report documents the last pteraspids, (armored, jawless members of the Heterostraci), which are otherwise only known from the Early Devonian of the Old Red Sandstone Continent. Tuberculate pteraspid heterostracans are described from the Middle Devonian beds of two formations in western North America. The late Givetian Yahatinda Formation of Alberta and British Columbia consists of channels cut into lower Paleozoic rocks and represents deposition in marine to littoral environments. Clavulaspis finis (Elliott et al., 2000a) new combination is redescribed from additional material from the Yahatinda Formation and reassigned to the new genus Clavulaspis because the original genus name is invalid. The Eifelian Spring Mountain beds of Idaho consist of a large channel that represents a clastic-dominated estuarine environment. It contains Scutellaspis wilsoni new genus new species, and the previously described species from the Spring Mountain beds is redescribed and reassigned to Ecphymaspis new genus, which was prompted by new material and a review of the validity of the original genus name. Phylogenetic analysis shows that these three new taxa form part of the derived clade Protaspididae.UUID: http://zoobank.org/9cf09b21-cec1-4ce4-bc2b-658d0b515e10

South American-Archaic Relations: Additional Comment

1951 ◽  
Vol 16 (4) ◽  
pp. 354-355
Author(s):  
Gordon R. Willey
Keyword(s):  
Focused Attention ◽  
South American ◽  
Cultural Relations ◽  
American Continent ◽  
The North ◽  
Additional Comment ◽  
Caribbean Area ◽  
The Caribbean ◽  
Cultural Connections ◽  
South American Continent

In a recent note Baerreis (1950) has given critical amplification to the question of possible cultural relations between the southeastern United States Archaic and the archaeologically known culture, or cultures, of the lower Parana River, Argentina. A paper of my own (Willey, 1949), on which Baerreis centers his discussion, focused attention on the Caribbean area and the north of the South American continent, giving only brief mention to interesting southeastern resemblances which may be found along the Parana and in the Sambaquis of southern Brazil. I agree that Baerreis has strengthened the case for cultural connections over and beyond the casual comments which I or others have offered.

Geodynamic study of the north of the Andes block (Colombia, Panama, Ecuador and Venezuela) through gnss-gps: models of displacements, models of deformation and definition of local and regional geodynamic structures.

2020 ◽  
Author(s):  
Berrocoso Manuel ◽  
Del Valle Arroyo Pablo Emilio ◽  
Colorado Jaramillo David Julián ◽  
Gárate Jorge ◽  
Fernández-Ros Alberto ◽  
...  
Keyword(s):  
South America ◽  
Seismic Activity ◽  
Great Part ◽  
Velocity Model ◽  
South American ◽  
The South ◽  
South American Plate ◽  
Northern Andes ◽  
Velocity Models ◽  
The North

<p>The northwest of South America is conformed by the territories of Ecuador, Colombia and Venezuela. Great part of these territories make up the Northern Andes Block (BAN). The tectonic and volcanic activity in the northwest of South America is directly related to the interaction of the South American plate, and the Nazca and Caribbean plates, with the Maracaibo and Panama-Chocó micro plates. The high seismic activity and the high magnitude of the recorded earthquakes make any study necessary to define this complex geodynamic region more precisely. This work presents the velocity models obtained through GNSS-GPS observations obtained in public continuous monitoring stations in the region. The observations of the Magna-eco network (Agustín Codazzi Geographic Institute) are integrated with models already obtained by other authors from the observations of the GEORED network (Colombian Geological Service). The observations have been processed using Bernese software v.52 using the PPP technique; obtaining topocentric time series. To obtain the speeds, a process of filtering and adjustment of the topocentric series has been carried out. Based on this velocity model, regional structures have been defined within the Northern Andes Block through a differentiation process based on the corresponding speeds of the South American, Nazca and Caribbean tectonic plates. Local geodynamic structures within the BAN itself have been established through cluster analysis based on both the direction and the magnitude of each of the vectors obtained. Finally, these structures have been correlated with the most significant geodynamic elements (fractures, faults, subduction processes, etc.) and with the associated seismic activity.</p>

Darwin's Early Notes on Coral Reef Formation

1984 ◽  
Vol 3 (2) ◽  
pp. 160-163 ◽  
Author(s):  
Frederick Burkhardt
Keyword(s):  
Coral Reef ◽  
South America ◽  
Point Of View ◽  
South American ◽  
American Continent ◽  
The Pacific ◽  
The Pacific Ocean ◽  
South American Continent ◽  
Reef Formation ◽  
Water Coral

Darwin's letters and some rough notes found in his field notebooks of 1835 confirm the statement in his Autobiography that he had formulated his theory of coral reef formation before the Beagle left South America and before he had seen a coral reef. His geological observations having convinced him of the elevation of the South American continent, Darwin predicted that evidence of a compensatory gradual subsidence of the Pacific Ocean floor would be found in the existence of shallow-water coral genera in the Pacific reef formations. The first draft of the theory was written on board the Beagle shortly after seeing the reefs of Moorea in November 1835. After visiting the Cocos (Keeling) Islands he wrote a summary of his view in a letter of April 1838, in which he expressed his conviction that he had found an explanation which would "put some of the facts in a more simple and connected point of view, than that in which they have hitherto been considered".

The Relations of Great Britain with Guiana

1923 ◽  
Vol 6 ◽  
pp. 1-21
Author(s):  
G. C. Edmundson
Keyword(s):  
Sixteenth Century ◽  
South American ◽  
American Continent ◽  
The South ◽  
Mountain Ranges ◽  
North East ◽  
The North ◽  
Terra Incognita ◽  
Rio Negro ◽  
South American Continent

Guiana, in the larger sense of the word, is that portion of the South American continent bounded on the north and north-east by the ocean; on the south, south-west and west by the river Amazon, its tributary the Rio Negro, the river Cassiquiare, which unites the river Negro to the river Orinoco, and by the river Orinoco itself. It is thus an island; as there is no break in the water-line that surrounds it. This larger Guiana is, however, divided into two distinct portions, separated from one another by a series of mountain ranges stretching from the Orinoco to the river Oyapok. That portion, which lies between these mountain ranges and the sea, differs entirely in character from the Guiana of the watersheds of the Amazon and Orinoco. It consists of a succession of tablelands, rising one above the other, and is watered by a large number of nearly parallel rivers, whose cataracts and frequent rapids render navigation into the interior, except by canoes, practically impossible. In this Guiana, the Guiana with which this paper deals, there have never been any Spanish or Portuguese settlements. At the end of the sixteenth century no attempt had been made by the Spaniards to cross the river Orinoco, or by the Portuguese, to reach the mouth of the river Amazon. Between these two rivers lay a terra incognita, of which nothing was known, until the publication of Ralegh's Discoverie of Guiana in 1595.

scholarly journals Influence of Surface Processes over Africa on the Atlantic Marine ITCZ and South American Precipitation

2005 ◽  
Vol 18 (23) ◽  
pp. 4993-5010 ◽  
Author(s):  
Samson M. Hagos ◽  
Kerry H. Cook
Keyword(s):  
Soil Moisture ◽  
South America ◽  
Atlantic Ocean ◽  
South American ◽  
Tropical Africa ◽  
Surface Wetness ◽  
The North ◽  
Symmetric Perturbation ◽  
Dry Conditions ◽  
Weak Influence

Abstract Previous studies show that the climatological precipitation over South America, particularly the Nordeste region, is influenced by the presence of the African continent. Here the influence of African topography and surface wetness on the Atlantic marine ITCZ (AMI) and South American precipitation are investigated. Cross-equatorial flow over the Atlantic Ocean introduced by north–south asymmetry in surface conditions over Africa shifts the AMI in the direction of the flow. African topography, for example, introduces an anomalous high over the southern Atlantic Ocean and a low to the north. This results in a northward migration of the AMI and dry conditions over the Nordeste region. The implications of this process on variability are then studied by analyzing the response of the AMI to soil moisture anomalies over tropical Africa. Northerly flow induced by equatorially asymmetric perturbations in soil moisture over northern tropical Africa shifts the AMI southward, increasing the climatological precipitation over northeastern South America. Flow associated with an equatorially symmetric perturbation in soil moisture, however, has a very weak cross-equatorial component and very weak influence on the AMI and South American precipitation. The sensitivity of the AMI to soil moisture perturbations over certain regions of Africa can possibly improve the skill of prediction.

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