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Bahe Formation
The Bahe Formation is a Late Miocene (Tortonian/Vallesian/ Bahean, about 11.6 to 9.0 mya) geological formation in Shaanxi, China. It has "a complex lithology of predominantly orange-yellow conglomerates, sandstones, tan-yellow sandy mudstones, and tan-red mudstones." The main fossil locality is in the Jiulaopo region on the left bank of the Bahe River in Lantian. Geology and environment Six general facies have been identified in the region: (1) massive or crudely bedded conglomerates, (2) cross-stratified conglomerate and sandstone deposits, (3) minor sandstone deposits, (4) fine-grained deposits, (5) gritty mudstone and sandstone deposits and (6) marl deposits. The presence of these types of facies suggest active channels, crevasse splays, sheet floods, and floodplains with paleosols and lakes. Thick and laterally pervasive units of fine-grained sediments, formed as suspension fall-out on the floodplain, indicating low-energy conditions and a relatively gentle surface gra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geological Formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by Abraham Gottlob Wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lantian County
Lantian County () is a county under the administration of Xi'an, the capital of Shaanxi province, China. It is the easternmost and second-most spacious (after Zhouzhi County) of the 13 county-level divisions of Xi'an. The county borders the prefecture-level cities of Weinan to the northeast and Shangluo to the southeast, Lintong District to the north, Chang'an District to the west, and Baqiao District to the northwest. Toponymy Lantian County was first founded in 379 BCE, and was named after the nearby Lantian Mountain (), located to the southeast of the current county seat. History Lantian County was first established in 379 BCE, in present-day , west of its current seat. The county was named for the nearby Lantian Mountain (). Numerous ancient Chinese texts, such as the ''Taiping Huanyu Ji'' and the '' Rites of Zhou'' state that the mountain was renown for its jade. From 446 CE to 487 CE, under the Xianbei-led Northern Wei, Lantian County was merged into Bacheng County ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erinaceus
''Erinaceus'' is a genus of hedgehog from the family of Erinaceidae. There are four main species of ''Erinaceus''. The range is all across Europe, throughout the Middle East, parts of Russia, and extending to northern China and Korea. The European hedgehog (''Erinaceus europaeus'') has been introduced to New Zealand.Macdonald, David W. The Encyclopedia of Mammals. New York, NY: Facts on File, 1984 . Description As is characteristic of other hedgehogs, members of ''Erinaceus'' have spines. These spines are a modification of the hair that is formed and strengthened by keratin. They contain hollow air filled gaps separated by thin inner layers of the spine to lessen the weight load.Grzimek, Bernhard, Neil Schlager, Donna Olendorf, and Melissa C. McDade. Grzimek's Animal Life Encyclopedia. Vol. 13. Detroit: Thomson Gale, 2004. Every spine is tapered at the end to form a point and also at the base where it then forms a bulb that is attached to the skin. The tapering at the base allo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dicerorhinus Sumatrensis
The Sumatran rhinoceros (''Dicerorhinus sumatrensis''), also known as the Sumatran rhino, hairy rhinoceros or Asian two-horned rhinoceros, is a rare member of the family Rhinocerotidae and one of five extant species of rhinoceros. It is the only extant species of the genus ''Dicerorhinus''. It is the smallest rhinoceros, although it is still a large mammal; it stands high at the shoulder, with a head-and-body length of and a tail of . The weight is reported to range from , averaging . Like both African species, it has two horns; the larger is the nasal horn, typically , while the other horn is typically a stub. A coat of reddish-brown hair covers most of the Sumatran rhino's body. The Sumatran rhinoceros once inhabited rainforests, swamps and cloud forests in India, Bhutan, Bangladesh, Myanmar, Laos, Thailand, Malaysia, Indonesia and southwestern China, particularly in Sichuan. It is now critically endangered, with only five substantial populations in the wild: four in Suma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dicerorhinus
''Dicerorhinus'' (Greek: "two" (dio), "horn" (keratos), "nose" (rhinos)) is a genus of the family Rhinocerotidae, consisting of a single extant species, the two-horned Sumatran rhinoceros (''D. sumatrensis''), and several extinct species. The genus likely originated in the Mid to Late Pliocene of Northern Indochina and South China. Many species attributed to the genus probably actually belong in ''Stephanorhinus.'' Taxonomy Historically, ''Dicerorhinus'' was a wastebasket taxon. Revisions by several authors over the years have removed many species: Transferred to ''Stephanorhinus'' *''Dicerorhinus merckii'' *''Dicerorhinus hemitoechus'' *''Dicerorhinus etruscus'' *''Dicerorhinus yunchuchenensis'' *''Dicerorhinus jeanvireti'' *''Dicerorhinus choukoutienensis'' (synonym of Merck's rhinoceros) *''Dicerorhinus orientalis'' (synonym of Merck's rhinoceros) *''Dicerorhinus nipponicus'' Transferred to ''Dihoplus'' *''Dicerorhinus megarhinus'' *''Dicerorhinus schleiermacheri'' *''Dicero ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Suidae
Suidae is a family of artiodactyl mammals which are commonly called pigs, hogs or swine. In addition to numerous fossil species, 18 extant species are currently recognized (or 19 counting domestic pigs and wild boars separately), classified into between four and eight genera. Within this family, the genus ''Sus'' includes the domestic pig, ''Sus scrofa domesticus'' or ''Sus domesticus'', and many species of wild pig from Europe to the Pacific. Other genera include babirusas and warthogs. All suids, or swine, are native to the Old World, ranging from Asia to Europe and Africa. The earliest fossil suids date from the Oligocene epoch in Asia, and their descendants reached Europe during the Miocene. Several fossil species are known and show adaptations to a wide range of different diets, from strict herbivory to possible carrion-eating (in Tetraconodontinae). Physical characteristics Suids belong to the order Artiodactyla, and are generally regarded as the living members of that or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chleuastochoerus
''Chleuastochoerus'' is an extinct genus in the pig family that lived in the Miocene and PliocenePickford, M. 1993. Old World suoid systematics, phylogeny, biogeography, and biostratigraphy. Paleont. Evol., 26-27:237-269 in Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eig ... and Eastern Asia. References Prehistoric Suidae Miocene mammals of Asia Miocene even-toed ungulates Prehistoric even-toed ungulate genera {{paleo-eventoedungulate-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhinoceros
A rhinoceros (; ; ), commonly abbreviated to rhino, is a member of any of the five extant species (or numerous extinct species) of odd-toed ungulates in the family Rhinocerotidae. (It can also refer to a member of any of the extinct species of the superfamily Rhinocerotoidea.) Two of the extant species are native to Africa, and three to South and Southeast Asia. Rhinoceroses are some of the largest remaining megafauna: all weigh at least one tonne in adulthood. They have a herbivorous diet, small brains (400–600 g) for mammals of their size, one or two horns, and a thick (1.5–5 cm), protective skin formed from layers of collagen positioned in a lattice structure. They generally eat leafy material, although their ability to ferment food in their hindgut allows them to subsist on more fibrous plant matter when necessary. Unlike other perissodactyls, the two African species of rhinoceros lack teeth at the front of their mouths; they rely instead on their lips to pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acerorhinus
''Acerorhinus'' was a genus of rhinoceros of the tribe Aceratheriini endemic to Asia from the Miocene, living from 13.6—7.0 mya existing for approximately . Among other locations, well-preserved ''Acerorhinus'' skull specimens have been found at Kerassiá in North Eubonea, Greece. Taxonomy ''Acerorhinus'' was named by Kretzoi (1942). Its type is ''Aceratherium zernowi''. Originally, many species in this genus including ''A. zernowi'' were assigned to '' Chilotherium''. It was assigned to Aceratheriini by Kaya and Heissig (2001); and to Aceratheriini by Antoine and Saraç (2005). Description ''Acerorhinus'' had very short legs, more like ''Teleoceras ''Teleoceras'' (Greek: "perfect" (teleos), "horn" (keratos)) is an extinct genus of grazing rhinoceros. It lived in North America during the Miocene and Pliocene epochs during the Hemingfordian to the end of Hemphillian from around 17.5 to 4. ...'' than other Aceratherines. While most other Aceratherines were grazers, ''Ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anastomosing
An anastomosis (, plural anastomoses) is a connection or opening between two things (especially cavities or passages) that are normally diverging or branching, such as between blood vessels, leaf veins, or streams. Such a connection may be normal (such as the foramen ovale in a fetus's heart) or abnormal (such as the patent foramen ovale in an adult's heart); it may be acquired (such as an arteriovenous fistula) or innate (such as the arteriovenous shunt of a metarteriole); and it may be natural (such as the aforementioned examples) or artificial (such as a surgical anastomosis). The reestablishment of an anastomosis that had become blocked is called a reanastomosis. Anastomoses that are abnormal, whether congenital or acquired, are often called fistulas. The term is used in medicine, biology, mycology, geology, and geography. Etymology Anastomosis: medical or Modern Latin, from Greek ἀναστόμωσις, anastomosis, "outlet, opening", Gr ana- "up, on, upon", stoma "mouth", ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sedimentary
Sedimentary rocks are types of rock (geology), rock that are formed by the accumulation or deposition of mineral or organic matter, organic particles at Earth#Surface, Earth's surface, followed by cementation (geology), 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 detritus (geology), geological detritus (minerals) or detritus, 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 wasting, 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Gradient
In vector calculus, the surface gradient is a vector differential operator that is similar to the conventional gradient. The distinction is that the surface gradient takes effect along a surface. For a surface S in a scalar field u, the surface gradient is defined and notated as :\nabla_S u = \nabla u - \mathbf (\mathbf \cdot \nabla u) where \mathbf is a unit normal to the surface.R. Shankar SubramanianBoundary Conditions in Fluid Mechanics Examining the definition shows that the surface gradient is the (conventional) gradient with the component normal to the surface removed (subtracted), hence this gradient is tangent to the surface. In other words, the surface gradient is the orthographic projection of the gradient onto the surface. The surface gradient arises whenever the gradient of a quantity over a surface is important. In the study of capillary surfaces for example, the gradient of spatially varying surface tension doesn't make much sense, however the surface gradient doe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
