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Australopithecus Bahrelghazali
''Australopithecus bahrelghazali'' is an extinct species of australopithecine discovered in 1995 at Koro Toro, Bahr el Gazel, Chad, existing around 3.5 million years ago in the Pliocene. It is the first and only australopithecine known from Central Africa, and demonstrates that this group was widely distributed across Africa as opposed to being restricted to East and southern Africa as previously thought. The validity of ''A. bahrelghazali'' has not been widely accepted, in favour of classifying the specimens as ''A. afarensis'', a better known Pliocene australopithecine from East Africa, because of the anatomical similarity and the fact that ''A. bahrelghazali'' is known only from 3 partial jawbones and an isolated premolar. The specimens inhabited a lakeside grassland environment with sparse tree cover, possibly similar to the modern Okavango Delta, and similarly predominantly ate C4 savanna foods—such as grasses, sedges, storage organs, or rhizomes—and to a lesser degre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Piacenzian
The Piacenzian is in the international geologic time scale the upper stage or latest age of the Pliocene. It spans the time between 3.6 ± 0.005 Ma and 2.588 ± 0.005 Ma (million years ago). The Piacenzian is after the Zanclean and is followed by the Gelasian (part of the Pleistocene). The Piacenzian is roughly coeval with the European land mammal age MN 16, overlaps the late Chapadmalalan and early Uquian South American land mammal age and falls inside the more extensive Blancan North American land mammal age. It also correlates with the Astian, Redonian, Reuverian and Romanian regional stages of Europe. Some authorities describe the British Red Crag Formation and Waltonian Stage as late Piacenzian, while others regard them as early Pleistocene. Carbon dioxide levels during the Piacenzian were similar to those of today, making this age, with global mean temperature 2–3 °C higher and sea levels about twenty meters higher than today, an important analogue for predictions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abel (hominid)
Abel (KT-12/H1) is the name given to the only specimen ever discovered of ''Australopithecus bahrelghazali''. Abel was found in January 1995 in Chad in the Kanem Region by the paleontologist Michel Brunet,Brunet, M., Beauvilain, A., Coppens, Y., Heintz, É., Moutaye, A.H.E et Pilbeam, D. (1995) - "The first australopithecine 2,500 kilometres west of the Rift Valley (Chad)", ''Nature'', 378, pp. 273-275. who named the fossil "Abel" in memory of his close friend Abel Brillanceau, who had died of malaria in 1989. Of Abel remains only part of a jaw, which explains the little information discernable concerning its way of life. The few teeth confirm it to be of the genus ''Australopithecus'': it has a second premolar with a broad and molarized crown, not dissimilar to the Lucy fossil, and as such to the ''Australopithecus afarensis''. See also *List of human evolution fossils The following tables give an overview of notable finds of hominin fossils and remains relating to human ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
In Situ
''In situ'' (; often not italicized in English) is a Latin phrase that translates literally to "on site" or "in position." It can mean "locally", "on site", "on the premises", or "in place" to describe where an event takes place and is used in many different contexts. For example, in fields such as physics, geology, chemistry, or biology, ''in situ'' may describe the way a measurement is taken, that is, in the same place the phenomenon is occurring without isolating it from other systems or altering the original conditions of the test. The opposite of ''in situ'' is ''ex situ''. Aerospace In the aerospace industry, equipment on-board aircraft must be tested ''in situ'', or in place, to confirm everything functions properly as a system. Individually, each piece may work but interference from nearby equipment may create unanticipated problems. Special test equipment is available for this ''in situ'' testing. It can also refer to repairs made to the aircraft structure or flight con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beryllium-9
Beryllium (4Be) has 11 known isotopes and 3 known isomers, but only one of these isotopes () is stable and a primordial nuclide. As such, beryllium is considered a monoisotopic element. It is also a mononuclidic element, because its other isotopes have such short half-lives that none are primordial and their abundance is very low (standard atomic weight is ). Beryllium is unique as being the only monoisotopic element with both an even number of protons and an odd number of neutrons. There are 25 other monoisotopic elements but all have odd atomic numbers, and even numbers of neutrons. Of the 10 radioisotopes of beryllium, the most stable are with a half-life of million years and with a half-life of . All other radioisotopes have half-lives under , most under . The least stable isotope is , with a half-life of . The 1:1 neutron–proton ratio seen in stable isotopes of many light elements (up to oxygen, and in elements with even atomic number up to calcium) is prevented in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beryllium-10
Beryllium-10 (10Be) is a radioactive isotope of beryllium. It is formed in the Earth's atmosphere mainly by cosmic ray spallation of nitrogen and oxygen. Beryllium-10 has a half-life of 1.39 × 106 years, and decays by beta decay to stable boron-10 with a maximum energy of 556.2 keV. It decays through the reaction 10Be→10B + e−. Light elements in the atmosphere react with high energy galactic cosmic ray particles. The spallation of the reaction products is the source of 10Be (t, u particles like n or p): :14N(t,5u)10Be; Example: 14N(n,p α)10Be :16O(t,7u)10Be Because beryllium tends to exist in solutions below about pH 5.5 (and rainwater above many industrialized areas can have a pH less than 5), it will dissolve and be transported to the Earth's surface via rainwater. As the precipitation quickly becomes more alkaline, beryllium drops out of solution. Cosmogenic 10Be thereby accumulates at the soil surface, where its relatively long half-life (1.387 million years) permit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiometric Dating
Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares the abundance of a naturally occurring radioactive isotope within the material to the abundance of its decay products, which form at a known constant rate of decay. The use of radiometric dating was first published in 1907 by Bertram Boltwood and is now the principal source of information about the absolute age of rocks and other geological features, including the age of fossilized life forms or the age of Earth itself, and can also be used to date a wide range of natural and man-made materials. Together with stratigraphic principles, radiometric dating methods are used in geochronology to establish the geologic time scale. Among the best-known techniques are radiocarbon dating, potassium–argon dating and uranium–lead dating. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sedimentary Rock
Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles to settle in place. The particles that form a sedimentary rock are called sediment, and may be composed of geological detritus (minerals) or biological detritus (organic matter). The geological detritus originated from weathering and erosion of existing rocks, or from the solidification of molten lava blobs erupted by volcanoes. The geological detritus is transported to the place of deposition by water, wind, ice or mass movement, which are called agents of denudation. Biological detritus was formed by bodies and parts (mainly shells) of dead aquatic organisms, as well as their fecal mass, suspended in water and slowly piling up on the floor of water bodies (marine snow). Sedimentation may also occur as dissolved minerals precipitate from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pelite
A pelite ( Greek: ''pelos'', "clay") or metapelite is a metamorphosed fine-grained sedimentary rock, i.e. mudstone or siltstone. The term was earlier used by geologists to describe a clay-rich, fine-grained clastic sediment or sedimentary rock, i.e. mud or a mudstone, the metamorphosed version of which would technically have been a ''metapelite''. It was equivalent to the now little-used Latin-derived term lutite.Potter, P.E., J.B. Maynard, and P.J. Depetris (2005) ''Muds and Mudstones.'' New York, New York, Springer. 279 pp. Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds. (2005) ''Glossary of Geology'' (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. A semipelite is defined in part as having similar chemical composition but being of a crystalloblastic nature. Pettijohn (1975) gives the following descriptive terms based on grain size, avoiding the use of terms such as clay or argillaceous which carry an implication of chemical composition. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paratype
In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype nor a syntype). Often there is more than one paratype. Paratypes are usually held in museum research collections. The exact meaning of the term ''paratype'' when it is used in zoology is not the same as the meaning when it is used in botany. In both cases however, this term is used in conjunction with ''holotype''. Zoology In zoological nomenclature, a paratype is officially defined as "Each specimen of a type series other than the holotype.", ''International Code of Zoological Nomenclature'' In turn, this definition relies on the definition of a "type series". A type series is the material (specimens of organisms) that was cited in the original publication of the new species or subspecies, and was not excluded from being type material by the author ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holotype
A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several examples, but explicitly designated as the holotype. Under the International Code of Zoological Nomenclature (ICZN), a holotype is one of several kinds of name-bearing types. In the International Code of Nomenclature for algae, fungi, and plants (ICN) and ICZN, the definitions of types are similar in intent but not identical in terminology or underlying concept. For example, the holotype for the butterfly '' Plebejus idas longinus'' is a preserved specimen of that subspecies, held by the Museum of Comparative Zoology at Harvard University. In botany, an isotype is a duplicate of the holotype, where holotype and isotypes are often pieces from the same individual plant or samples from the same gathering. A holotype is not necessarily " ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Classical Arabic
Classical Arabic ( ar, links=no, ٱلْعَرَبِيَّةُ ٱلْفُصْحَىٰ, al-ʿarabīyah al-fuṣḥā) or Quranic Arabic is the standardized literary form of Arabic used from the 7th century and throughout the Middle Ages, most notably in Umayyad and Abbasid literary texts such as poetry, elevated prose and oratory, and is also the liturgical language of Islam. The first comprehensive description of ''Al-ʿArabiyyah'' "Arabic", Sibawayh's ''al''-''Kitāb'', was upon a corpus of poetic texts, in addition to the Qurʾān and Bedouin informants whom he considered to be reliable speakers of the ''ʿarabiyya''. Modern Standard Arabic is its direct descendant used today throughout the Arab world in writing and in formal speaking, for example prepared speeches, some radio and TV broadcasts and non-entertainment content. Whilst the lexis and stylistics of Modern Standard Arabic are different from Classical Arabic, the morphology and syntax have remained basically unchang ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
David Pilbeam
David Pilbeam (born 21 November 1940 in Brighton, Sussex, England) is the Henry Ford II Professor of the Social Sciences at Harvard University and curator of paleoanthropology at the Peabody Museum of Archaeology and Ethnology. He is a member of the National Academy of Sciences. He received his Ph.D. from Yale University. Biography Pilbeam has produced numerous publications related to hominoid evolution since the mid-1960s, with some of his papers reprinted in later books. In the 1970s, he was a co-discoverer, in the Potwar Plateau of Pakistan, of a nearly complete skull subsequently described as belonging to '' Sivapithecus indicus'', an extinct Late Miocene great ape, on which he published several papers. In 2005, in honour of his 65th birthday, Pilbeams' students, colleagues, collaborators and friends assembled a collection to honour his work. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
