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Equisetum Dimorphum
''Equisetum dimorphum'' is an extinct horsetail species of the family Equisetaceae, and one of the oldest records of the genus ''Equisetum''. It was found in rocks from the Lower Jurassic of Chubut, Argentina, among other plants as ferns, conifers and pteridosperms. Their remains consist of stems, leaves, strobili, and pagoda structures, which are preserved as impressions and casts. The combination of fine grained sediment, and the probable silica deposits in the epidermis of the plant, have managed to conserve not only its gross morphology, but also epidermal details not often present in this kind of preservation. This species was described in 2015 in Ameghiniana by a team led by Andres Elgorriaga, that included investigators of the Museum of Paleontology Egidio Feruglio, the Swedish Museum of Natural History, and the Buenos Aires University. Description The stems are dimorphic, unbranched and present no sign of superficial ribs and valleys. They are hollow except at the nodal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pliensbachian
The Pliensbachian is an age of the geologic timescale and stage in the stratigraphic column. It is part of the Early or Lower Jurassic Epoch or Series and spans the time between 190.8 ± 1.5 Ma and 182.7 ± 1.5 Ma (million years ago). The Pliensbachian is preceded by the Sinemurian and followed by the Toarcian. The Pliensbachian ended with the extinction event called the Toarcian turnover. During the Pliensbachian, the middle part of the Lias was deposited in Europe. The Pliensbachian is roughly coeval with the Charmouthian regional stage of North America. Stratigraphic definitions The Pliensbachian takes its name from the hamlet of Pliensbach in the community of Zell unter Aichelberg in the Swabian Alb, some 30 km east of Stuttgart in Germany. The name was introduced into scientific literature by German palaeontologist Albert Oppel in 1858. The base of the Pliensbachian is at the first appearances of the ammonite species '' Bifericeras donovani'' and genera ''Apoderocer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buenos Aires University
The University of Buenos Aires ( es, Universidad de Buenos Aires, UBA) is a public university, public research university in Buenos Aires, Argentina. Established in 1821, it is the premier institution of higher learning in the country and one of the most prestigious universities of Ibero-America. It has educated 17 President of Argentina, Argentine presidents, produced four of the country's five Nobel Prize laureates, and is responsible for approximately 40% of the country's research output. The ''QS World University Rankings'' currently places the UBA at number 67, the highest ranking university in the Spanish-speaking world. The university's academic strength and regional leadership make it attractive to many international students, especially at the postgraduate level. Just over 4 percent of undergraduates are foreigners, while 15 percent of postgraduate students come from abroad. The Faculty of Economic Sciences, University of Buenos Aires, Faculty of Economic Sciences has t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossils Of Argentina
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the absolute ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flora Of Argentina
The Environment of Argentina is characterised by high biodiversity. Biodiversity Subtropical plants dominate the Gran Chaco in the north, with the ''Dalbergia'' genus of trees well represented by Brazilian rosewood and the quebracho tree; also predominant the wacho white and black algarrobo trees ('' Prosopis alba'' and ''Prosopis nigra''). Savannah-like areas exist in the drier regions nearer the Andes. Aquatic plants thrive in the wetlands of Argentina. In central Argentina the ''humid pampas'' are a true tallgrass prairie ecosystem. The original pampa had virtually no trees; some imported species like the American sycamore or eucalyptus are present along roads or in towns and country estates (''estancias''). The only tree-like plant native to the pampa is the evergreen Ombú. The surface soils of the pampa are a deep black color, primarily mollisols, known commonly as ''humus''. This makes the region one of the most agriculturally productive on Earth; however, this is also res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jurassic Argentina
The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of the Mesozoic Era and is named after the Jura Mountains, where limestone strata from the period were first identified. The start of the Jurassic was marked by the major Triassic–Jurassic extinction event, associated with the eruption of the Central Atlantic Magmatic Province. The beginning of the Toarcian Stage started around 183 million years ago and is marked by an extinction event associated with widespread oceanic anoxia, ocean acidification, and elevated temperatures likely caused by the eruption of the Karoo-Ferrar large igneous provinces. The end of the Jurassic, however, has no clear boundary with the Cretaceous and is the only boundary between geological periods to remain formally undefined. By the beginning of the Jurassic, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
