Bajo Barreal Formation
The Bajo Barreal Formation is a geological formation in the Golfo San Jorge Basin of Chubut and Santa Cruz, Argentina whose strata date back to the Middle Cenomanian to Late Turonian. The formation was first described by Teruggi & Rossetto in 1963; the sandstones, mudstones and tuff were deposited in a fluvial environment. The upper part of formation is laterally equivalent to the Yacimiento El Trébol and Meseta Espinosa Formation and the lower part to the Laguna Palacios, Cañadón Seco and Comodoro Rivadavia Formations; the Bajo Barreal Formation is a reservoir rock in the Golfo San Jorge Basin. Dinosaur remains are among the fossils. Dinosaur remains include the abelisaurid theropod Xenotarsosaurus bonapartei, as well as indeterminate teeth belonging to carcharodontosaurids and dromaeosaurids. Other fossilsOther fossils found in the formation include: List of dinosaur-bearing rock formations Mata Amarilla Formation, contemporaneous formation of the Austral Basin Lisandro Formation, contemporaneous formation of the Neuquén Basin Casal, Gabriel A..
2016. Ordenamiento y caracterización faunística del Cretácico Superior del Grupo Chubut, Cuenca del Golfo San Jorge, Argentina. Revista Brasileira de Paleontologia 19. 53–70. Accessed 2019-02-16. Martínez, Rubén D. F.. Lamanna. Ridgely. 2016. A Basal Lithostrotian Titanosaur with a Complete Skull: Implications for the Evolution and Paleobiology of Titanosauria. PLoS ONE 11. E0151661. Accessed 2019-02-16. Sylwan, Claudio A. 2001. Geology of the Golfo San Jorge Basin, Argentina. Journal of Iberian Geology 27. 123–157. Accessed 2018-09-04. Weishampel, David B.. 2004. The Dinosauria, 2nd edition, 1–880. Berkeley: University of California Press. Accessed 2019-02-21. ISBN 0-520-24209-2 G. Casal and L. Ibiricu. 2010. Materiales asignables a Epachthosaurus Powell, 1990, de la Formación Bajo Barreal, Cretácico Superior, Argentina. Revista Brasileira de Paleontologia 13:247-256 L. M. Ibiricu, G. A. Casal, R. D. Martinez, M. C. Lamanna, M. Luna and L. Salgado. 2013. Katepensaurus goicoecheai, gen. et sp. nov. A Late Cretaceous rebbachisaurid from central Patagonia, Argentina.
Journal of Vertebrate Paleontology 33:1351-1366 L. M. Ibiricu, G. A. Casal, M. C. Lamanna, R. D. Martínez, J. D. Harris and K. J. Lacovara. 2012. The southernmost records of Rebbachisauridae, from early Late Cretaceous deposits in central Patagonia. Cretaceous Research 34:220-232 R. D. Martínez, F. E. Novas, A. Ambrosio. 2004. Abelisaurid remains from southern Patagonia. Actas I del Congreso Ltinoamericano de Paleontología de Vertebrados. Ameghiniana 41:577-585 R. D. Martínez and F. E. Novas. 1997. Un nuevo tetanuro de la Formación Bajo Barreal, Patagonia. Ameghiniana 34:538 R. D. Martínez, A. Maure, M. Oliva and M. Luna. 1993. Un maxilar de Theropoda de la Formación Bajo Barreal, Cretacico Tardio, Argentina. Ameghiniana 30:109-110 J. C. Sciutto and R. D. Martínez. 1994. Un nuevo yacimiento fosilífero de la Formación Bajo Barreal y su fauna de saurópodos. Naturalia Patagonica, Ciencias de la Tierra 2:27-47
Paleontology or palaeontology is the scientific study of life that existed prior to, sometimes including, the start of the Holocene Epoch. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments. Paleontological observations have been documented as far back as the 5th century BC; the science became established in the 18th century as a result of Georges Cuvier's work on comparative anatomy, developed in the 19th century. The term itself originates from Greek παλαιός, palaios, "old, ancient", ὄν, on, "being, creature" and λόγος, logos, "speech, study". Paleontology lies on the border between biology and geology, but differs from archaeology in that it excludes the study of anatomically modern humans, it now uses techniques drawn from a wide range of sciences, including biochemistry and engineering. Use of all these techniques has enabled paleontologists to discover much of the evolutionary history of life all the way back to when Earth became capable of supporting life, about 3.8 billion years ago.
As knowledge has increased, paleontology has developed specialised sub-divisions, some of which focus on different types of fossil organisms while others study ecology and environmental history, such as ancient climates. Body fossils and trace fossils are the principal types of evidence about ancient life, geochemical evidence has helped to decipher the evolution of life before there were organisms large enough to leave body fossils. Estimating the dates of these remains is essential but difficult: sometimes adjacent rock layers allow radiometric dating, which provides absolute dates that are accurate to within 0.5%, but more paleontologists have to rely on relative dating by solving the "jigsaw puzzles" of biostratigraphy. Classifying ancient organisms is difficult, as many do not fit well into the Linnaean taxonomy classifying living organisms, paleontologists more use cladistics to draw up evolutionary "family trees"; the final quarter of the 20th century saw the development of molecular phylogenetics, which investigates how organisms are related by measuring the similarity of the DNA in their genomes.
Molecular phylogenetics has been used to estimate the dates when species diverged, but there is controversy about the reliability of the molecular clock on which such estimates depend. The simplest definition of paleontology is "the study of ancient life"; the field seeks information about several aspects of past organisms: "their identity and origin, their environment and evolution, what they can tell us about the Earth's organic and inorganic past". Paleontology is one of the historical sciences, along with archaeology, astronomy, cosmology and history itself: it aims to describe phenomena of the past and reconstruct their causes. Hence it has three main elements: description of past phenomena; when trying to explain the past and other historical scientists construct a set of hypotheses about the causes and look for a smoking gun, a piece of evidence that accords with one hypothesis over the others. Sometimes the smoking gun is discovered by a fortunate accident during other research. For example, the discovery by Luis and Walter Alvarez of iridium, a extra-terrestrial metal, in the Cretaceous–Tertiary boundary layer made asteroid impact the most favored explanation for the Cretaceous–Paleogene extinction event, although the contribution of volcanism continues to be debated.
The other main type of science is experimental science, said to work by conducting experiments to disprove hypotheses about the workings and causes of natural phenomena. This approach cannot prove a hypothesis, since some experiment may disprove it, but the accumulation of failures to disprove is compelling evidence in favor. However, when confronted with unexpected phenomena, such as the first evidence for invisible radiation, experimental scientists use the same approach as historical scientists: construct a set of hypotheses about the causes and look for a "smoking gun". Paleontology lies between biology and geology since it focuses on the record of past life, but its main source of evidence is fossils in rocks. For historical reasons, paleontology is part of the geology department at many universities: in the 19th and early 20th centuries, geology departments found fossil evidence important for dating rocks, while biology departments showed little interest. Paleontology has some overlap with archaeology, which works with objects made by humans and with human remains, while paleontologists are interested in the characteristics and evolution of humans as a species.
When dealing with evidence about humans and paleontologists may work together – for example paleontologists might identify animal or plant fossils around an archaeological site, to discover what the people who lived there ate. In addition, paleontology borrows techniques from other sciences, including biology, ecology, chemistry and mathematics. For example, geochemical signatures from rocks may help to discover when life first arose on Earth, analyses of carbon isotope ratios may help to identify climate changes and to explain major transitions such as the Permian–Triassic extinction event. A recent discipline, molecular phylogenetics, compares the DNA and RNA of modern organisms to re-construct the "family trees" of their
Sarmiento is a town in the province of Chubut, Argentina. It has about 8,000 inhabitants as per the 2001 census, is the head town of the department of the same name, it is located on the so-called Central Corridor of Patagonia, in a fertile valley amidst an otherwise arid region, 140 km west from Comodoro Rivadavia, in the south of Chubut. It sits between Lake Musters and Lake Colhue Huapi. Notable attractions are caves with Aborigine hand paintings. Sarmiento was born as a colony of immigrants from Wales. In the early 1900s it experienced an influx of immigrants from Lithuania. In 1900, Argentine authority was locally established when the Swedish former sailor Oscar Lundqwist, appointed police commissioner to Sarmiento, set up the first "comisaría" in Sarmiento, it was situated next to "Las Tres Casas" where the Jones families from Wales and the Briton Pryce lived. In 1903, 600 Afrikaner families arrived in Argentina following the loss of the Second Boer War, they settled in the region as it had access to water unlike the coastal city of Comodoro Rivadavia where they first settled.
The descendants of these colonists make up a large portion of the population of Sarmiento and still speak Afrikaans and attend the Nederduitse Gereformeerde Kerk to this day. As as the 1960s Afrikaans was the most spoken language however this has changed as the town's Afrikaans population has become more assimilated into Argentinian culture and society. In 2016, an important fossil dinosaur was discovered near the town, it is named Sarmientosaurus musacchio in honor of the town and of the late Dr. Eduardo Musacchio, a paleontologist and professor at the National University of Patagonia San Juan Bosco. Under the Köppen climate classification, Sarmiento has a cold semi-arid climate that borders on a cold desert climate with warm summers and cool winters; the coldest temperature at low elevation recorded in South America, −32.8 °C, was recorded in Sarmiento on June 1, 1907. Precipitation is low, averaging only 183 millimetres per year. Municipal information: Municipal Affairs Federal Institute, Municipal Affairs Secretariat, Ministry of Interior, Argentina.
Colonia Sarmiento — Official website
The Devonian is a geologic period and system of the Paleozoic, spanning 60 million years from the end of the Silurian, 419.2 million years ago, to the beginning of the Carboniferous, 358.9 Mya. It is named after Devon, where rocks from this period were first studied; the first significant adaptive radiation of life on dry land occurred during the Devonian. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. By the middle of the Devonian, several groups of plants had evolved leaves and true roots, by the end of the period the first seed-bearing plants appeared. Various terrestrial arthropods became well-established. Fish reached substantial diversity during this time, leading the Devonian to be dubbed the "Age of Fishes." The first ray-finned and lobe-finned bony fish appeared, while the placoderms began dominating every known aquatic environment. The ancestors of all four-limbed vertebrates began adapting to walking on land, as their strong pectoral and pelvic fins evolved into legs.
In the oceans, primitive sharks became more numerous than in the Late Ordovician. The first ammonites, species of molluscs, appeared. Trilobites, the mollusc-like brachiopods and the great coral reefs, were still common; the Late Devonian extinction which started about 375 million years ago affected marine life, killing off all placodermi, all trilobites, save for a few species of the order Proetida. The palaeogeography was dominated by the supercontinent of Gondwana to the south, the continent of Siberia to the north, the early formation of the small continent of Euramerica in between; the period is named after Devon, a county in southwestern England, where a controversial argument in the 1830s over the age and structure of the rocks found distributed throughout the county was resolved by the definition of the Devonian period in the geological timescale. The Great Devonian Controversy was a long period of vigorous argument and counter-argument between the main protagonists of Roderick Murchison with Adam Sedgwick against Henry De la Beche supported by George Bellas Greenough.
Murchison and Sedgwick named the period they proposed as the Devonian System. While the rock beds that define the start and end of the Devonian period are well identified, the exact dates are uncertain. According to the International Commission on Stratigraphy, the Devonian extends from the end of the Silurian 419.2 Mya, to the beginning of the Carboniferous 358.9 Mya. In nineteenth-century texts the Devonian has been called the "Old Red Age", after the red and brown terrestrial deposits known in the United Kingdom as the Old Red Sandstone in which early fossil discoveries were found. Another common term is "Age of the Fishes", referring to the evolution of several major groups of fish that took place during the period. Older literature on the Anglo-Welsh basin divides it into the Downtonian, Dittonian and Farlovian stages, the latter three of which are placed in the Devonian; the Devonian has erroneously been characterised as a "greenhouse age", due to sampling bias: most of the early Devonian-age discoveries came from the strata of western Europe and eastern North America, which at the time straddled the Equator as part of the supercontinent of Euramerica where fossil signatures of widespread reefs indicate tropical climates that were warm and moderately humid but in fact the climate in the Devonian differed during its epochs and between geographic regions.
For example, during the Early Devonian, arid conditions were prevalent through much of the world including Siberia, North America, China, but Africa and South America had a warm temperate climate. In the Late Devonian, by contrast, arid conditions were less prevalent across the world and temperate climates were more common; the Devonian Period is formally broken into Early and Late subdivisions. The rocks corresponding to those epochs are referred to as belonging to the Lower and Upper parts of the Devonian System. Early DevonianThe Early Devonian lasted from 419.2 ± 2.8 to 393.3 ± 2.5 and began with the Lochkovian stage, which lasted until the Pragian. It spanned from 410.8 ± 2.8 to 407.6 ± 2.5, was followed by the Emsian, which lasted until the Middle Devonian began, 393.3± 2.7 million years ago. During this time, the first ammonoids appeared. Ammonoids during this time period differed little from their nautiloid counterparts; these ammonoids belong to the order Agoniatitida, which in epochs evolved to new ammonoid orders, for example Goniatitida and Clymeniida.
This class of cephalopod molluscs would dominate the marine fauna until the beginning of the Mesozoic era. Middle DevonianThe Middle Devonian comprised two subdivisions: first the Eifelian, which gave way to the Givetian 387.7± 2.7 million years ago. During this time the jawless agnathan fishes began to decline in diversity in freshwater and marine environments due to drastic environmental changes and due to the increasing competition and diversity of jawed fishes; the shallow, oxygen-depleted waters of Devonian inland lakes, surrounded by primitive plants, provided the environment necessary for certain early fish to develop such essential characteristics as well developed lungs, the ability to crawl out of the water and onto the land for short periods of time. Late DevonianFinally, the Late Devonian started with the Frasnian, 382.7 ± 2.8 to 372.2 ± 2.5, during which the first forests took shape on land. The first tetrapods appeared in the fossil record in the ensuing Famennian subdivisi
National University of Patagonia San Juan Bosco
The National University of the Patagonia San Juan Bosco is a higher education establishment in Patagonia, southern Argentina. It was created on February 25, 1980, by law 22.713, as the merge of two national universities: the "Universidad de San Juan Bosco" and "Universidad Nacional de la Patagonia". It is named after patron saint of the area; the university has four schools - Engineering, Humanities and Natural Sciences, spread over several cities in Patagonia: Puerto Madryn, Esquel, Comodoro Rivadavia, Ushuaia. The central faculty is located in Comodoro Rivadavia; the University has as of 2005 14,000 students, with 5000 in the main school. In 2015, the university opened to the inhabitants of the Falkland Islands; the academic program was translated into English, language courses were designed and a system of special scholarship was established. Thus, National University of the Patagonia San Juan Bosco became the first Argentine university to extend their academic offer to Falkland Islanders. Viviana Alder, marine microbiologist, Argentine Antarctic researcher List of Argentine universities Science and Education in Argentina Argentine Higher Education Official Site
The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous epoch, or a stage in the Upper Cretaceous series. It spans the time between 93.9 ± 0.8 Ma and 89.8 ± 1 Ma. The Turonian underlies the Coniacian stage. At the beginning of the Turonian an anoxic event took place, called the Cenomanian-Turonian boundary event or the "Bonarelli Event"; the Turonian was defined by the French paleontologist Alcide d'Orbigny in 1842. Orbigny named it after the French city of Tours in the region of Touraine, the original type locality; the base of the Turonian stage is defined as the place where the ammonite species Wutinoceras devonense first appears in the stratigraphic column. The official reference profile for the base of the Turonian is located in the Rock Canyon anticline near Pueblo, Colorado; the top of the Turonian stage is defined as the place in the stratigraphic column where the inoceramid bivalve species Cremnoceramus rotundatus first appears. The Turonian is sometimes subdivided in Lower/Early and Upper/Late substages or subages.
In the Tethys domain, it contains the following ammonite biozones: zone of Subprionocyclus neptuni zone of Collignoniceras woollgari zone of Mammites nodosoides zone of Watinoceras coloradoense or Watinoceras devonense Other important index fossils are species of the inoceramid genus Inoceramus. Inoceramids are bivalve Mollusca related to today's mussels. Gradstein, F. M.. G. & Smith, A. G.. Kennedy, W. J.. & Cobban, W. A.. S. A. Episodes 28: pp 93–104. GeoWhen Database - Turonian Late Cretaceous timescale, at the website of the subcommission for stratigraphic information of the ICS Stratigraphic charts of the Cretaceous: and, at the website of Norges Network of offshore records of geology and stratigraphy Turonian Microfossils: 48 images of Foraminifera
The Jurassic period was a geologic period and system that spanned 56 million years from the end of the Triassic Period 201.3 million years ago to the beginning of the Cretaceous Period 145 Mya. The Jurassic constitutes the middle period of the Mesozoic Era known as the Age of Reptiles; the start of the period was marked by the major Triassic–Jurassic extinction event. Two other extinction events occurred during the period: the Pliensbachian-Toarcian extinction in the Early Jurassic, the Tithonian event at the end; the Jurassic period is divided into three epochs: Early and Late. In stratigraphy, the Jurassic is divided into the Lower Jurassic, Middle Jurassic, Upper Jurassic series of rock formations; the Jurassic is named after the Jura Mountains within the European Alps, where limestone strata from the period were first identified. By the beginning of the Jurassic, the supercontinent Pangaea had begun rifting into two landmasses: Laurasia to the north, Gondwana to the south; this created more coastlines and shifted the continental climate from dry to humid, many of the arid deserts of the Triassic were replaced by lush rainforests.
On land, the fauna transitioned from the Triassic fauna, dominated by both dinosauromorph and crocodylomorph archosaurs, to one dominated by dinosaurs alone. The first birds appeared during the Jurassic, having evolved from a branch of theropod dinosaurs. Other major events include the appearance of the earliest lizards, the evolution of therian mammals, including primitive placentals. Crocodilians made the transition from a terrestrial to an aquatic mode of life; the oceans were inhabited by marine reptiles such as ichthyosaurs and plesiosaurs, while pterosaurs were the dominant flying vertebrates. The chronostratigraphic term "Jurassic" is directly linked to the Jura Mountains, a mountain range following the course of the France–Switzerland border. During a tour of the region in 1795, Alexander von Humboldt recognized the limestone dominated mountain range of the Jura Mountains as a separate formation that had not been included in the established stratigraphic system defined by Abraham Gottlob Werner, he named it "Jura-Kalkstein" in 1799.
The name "Jura" is derived from the Celtic root *jor via Gaulish *iuris "wooded mountain", borrowed into Latin as a place name, evolved into Juria and Jura. The Jurassic period is divided into three epochs: Early and Late. In stratigraphy, the Jurassic is divided into the Lower Jurassic, Middle Jurassic, Upper Jurassic series of rock formations known as Lias and Malm in Europe; the separation of the term Jurassic into three sections originated with Leopold von Buch. The faunal stages from youngest to oldest are: During the early Jurassic period, the supercontinent Pangaea broke up into the northern supercontinent Laurasia and the southern supercontinent Gondwana; the Jurassic North Atlantic Ocean was narrow, while the South Atlantic did not open until the following Cretaceous period, when Gondwana itself rifted apart. The Tethys Sea closed, the Neotethys basin appeared. Climates were warm, with no evidence of a glacier having appeared; as in the Triassic, there was no land over either pole, no extensive ice caps existed.
The Jurassic geological record is good in western Europe, where extensive marine sequences indicate a time when much of that future landmass was submerged under shallow tropical seas. In contrast, the North American Jurassic record is the poorest of the Mesozoic, with few outcrops at the surface. Though the epicontinental Sundance Sea left marine deposits in parts of the northern plains of the United States and Canada during the late Jurassic, most exposed sediments from this period are continental, such as the alluvial deposits of the Morrison Formation; the Jurassic was a time of calcite sea geochemistry in which low-magnesium calcite was the primary inorganic marine precipitate of calcium carbonate. Carbonate hardgrounds were thus common, along with calcitic ooids, calcitic cements, invertebrate faunas with dominantly calcitic skeletons; the first of several massive batholiths were emplaced in the northern American cordillera beginning in the mid-Jurassic, marking the Nevadan orogeny. Important Jurassic exposures are found in Russia, South America, Japan and the United Kingdom.
In Africa, Early Jurassic strata are distributed in a similar fashion to Late Triassic beds, with more common outcrops in the south and less common fossil beds which are predominated by tracks to the north. As the Jurassic proceeded and more iconic groups of dinosaurs like sauropods and ornithopods proliferated in Africa. Middle Jurassic strata are neither well studied in Africa. Late Jurassic strata are poorly represented apart from the spectacular Tendaguru fauna in Tanzania; the Late Jurassic life of Tendaguru is similar to that found in western North America's Morrison Formation. During the Jurassic period, the primary vertebrates living in the sea were marine reptiles; the latter include ichthyosaurs, which were at the peak of their diversity, plesiosaurs and marine crocodiles of the families Teleosauridae and Metriorhynchidae. Numerous turtles could be found in rivers. In the invertebrate world, several new groups appeared, including rudists (a reef-formi