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Small Shelly Fauna
The small shelly fauna, small shelly fossils (SSF), or early skeletal fossils (ESF) are mineralized fossils, many only a few millimetres long, with a nearly continuous record from the latest stages of the Ediacaran to the end of the Early Cambrian Period. They are very diverse, and there is no formal definition of "small shelly fauna" or "small shelly fossils". Almost all are from earlier rocks than more familiar fossils such as trilobites. Since most SSFs were preserved by being covered quickly with phosphate and this method of preservation is mainly limited to the late Ediacaran and early Cambrian periods, the animals that made them may actually have arisen earlier and persisted after this time span. Some of the fossils represent the entire skeletons of small organisms, including the mysterious '' Cloudina'' and some snail-like molluscs. However, the bulk of the fossils are fragments or disarticulated remains of larger organisms, including sponges, molluscs, slug-like halkier ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biomineralization
Biomineralization, also written biomineralisation, is the process by which living organisms produce minerals, often to harden or stiffen existing tissues. Such tissues are called mineralized tissues. It is an extremely widespread phenomenon; all six taxonomic kingdoms contain members that are able to form minerals, and over 60 different minerals have been identified in organisms. Examples include silicates in algae and diatoms, carbonates in invertebrates, and calcium phosphates and carbonates in vertebrates. These minerals often form structural features such as sea shells and the bone in mammals and birds. Organisms have been producing mineralized skeletons for the past 550 million years. Calcium carbonates and calcium phosphates are usually crystalline, but silica organisms (sponges, diatoms...) are always non crystalline minerals. Other examples include copper, iron and gold deposits involving bacteria. Biologically formed minerals often have special uses such as ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silica
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and most abundant families of materials, existing as a compound of several minerals and as a synthetic product. Notable examples include fused quartz, fumed silica, silica gel, opal and aerogels. It is used in structural materials, microelectronics (as an electrical insulator), and as components in the food and pharmaceutical industries. Structure In the majority of silicates, the silicon atom shows tetrahedral coordination, with four oxygen atoms surrounding a central Si atomsee 3-D Unit Cell. Thus, SiO2 forms 3-dimensional network solids in which each silicon atom is covalently bonded in a tetrahedral manner to 4 oxygen atoms. In contrast, CO2 is a linear molecule. The starkly different structures of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Punctuated Equilibrium
In evolutionary biology, punctuated equilibrium (also called punctuated equilibria) is a theory that proposes that once a species appears in the fossil record, the population will become stable, showing little evolutionary change for most of its geological history. : ''Reprinted in'' * * This state of little or no morphological change is called ''stasis''. When significant evolutionary change occurs, the theory proposes that it is generally restricted to rare and geologically rapid events of branching speciation called cladogenesis. Cladogenesis is the process by which a species splits into two distinct species, rather than one species gradually transforming into another. Punctuated equilibrium is commonly contrasted with phyletic gradualism, the idea that evolution generally occurs uniformly by the steady and gradual transformation of whole lineages (anagenesis). In 1972, paleontologists Niles Eldredge and Stephen Jay Gould published a landmark paper developing the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stephen Jay Gould
Stephen Jay Gould (; September 10, 1941 – May 20, 2002) was an American paleontologist, evolutionary biologist, and historian of science. He was one of the most influential and widely read authors of popular science of his generation. Gould spent most of his career teaching at Harvard University and working at the American Museum of Natural History in New York. In 1996, Gould was hired as the Vincent Astor Visiting Research Professor of Biology at New York University, after which he divided his time teaching between there and Harvard. Gould's most significant contribution to evolutionary biology was the theory of punctuated equilibrium developed with Niles Eldredge in 1972.Eldredge, Niles, and S. J. Gould (1972)"Punctuated equilibria: an alternative to phyletic gradualism."In T.J.M. Schopf, ed., ''Models in Paleobiology''. San Francisco: Freeman, Cooper and Company, pp. 82–115. The theory proposes that most evolution is characterized by long periods of evolutionary st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Niles Eldredge
Niles Eldredge (; born August 25, 1943) is an American biologist and paleontologist, who, along with Stephen Jay Gould, proposed the theory of punctuated equilibrium in 1972. Education Eldredge began his undergraduate studies in Latin at Columbia University. Before completing his degree he switched to the study of geology under Norman D. Newell. It was at this time that his work at the American Museum of Natural History began, under the combined Columbia University-American Museum graduate studies program. Eldredge graduated ''summa cum laude'' from Columbia College of Columbia University in 1965, and enrolled in the university's doctoral program while continuing his research at the museum. He completed his PhD in 1969. Career and research Paleontology In 1969, Eldredge became a curator in the Department of Invertebrates at the American Museum of Natural History, and subsequently a curator in the Invertebrate Paleontology section, a position from which he recently retired. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Preston Cloud
Preston Ercelle Cloud, Jr. (September 26, 1912 – January 16, 1991) was an American earth scientist, biogeologist, cosmologist, and paleontologist. He served in the United States Navy (in which he was a bantamweight boxing champion), and led several field explorations of the U.S. Geological Survey. In academia, he was a member of the faculty of Harvard University, University of Minnesota, University of California, Los Angeles, and lastly University of California, Santa Barbara. He was best known for his work on the geologic time scale and the origin of life on Earth, and as a pioneering ecologist and environmentalist. His works on the significance of Cambrian fossils in the 1940s led to the development of the concept " Cambrian explosion," for which he coined the phrase "eruptive evolution." Early life and education Cloud was born in West Upton, Massachusetts. He was the third of seven children of Preston Ercelle and Pauline L. (''née'' Wiedemann) Cloud. His father was a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soviet Union
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a Federation, federal union of Republics of the Soviet Union, fifteen national republics; in practice, both Government of the Soviet Union, its government and Economy of the Soviet Union, its economy were highly Soviet-type economic planning, centralized until its final years. It was a one-party state governed by the Communist Party of the Soviet Union, with the city of Moscow serving as its capital as well as that of its largest and most populous republic: the Russian Soviet Federative Socialist Republic, Russian SFSR. Other major cities included Saint Petersburg, Leningrad (Russian SFSR), Kyiv, Kiev (Ukrainian Soviet Socialist Republic, Ukrainian SSR), Minsk (Byelorussian Soviet Socialist Republic, Byelorussian SSR), Tas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archaeocyatha
Archaeocyatha (or archaeocyathids 'ancient cups') is a taxon of extinct, sessile, reef-building marine sponges that lived in warm tropical and subtropical waters during the Cambrian Period. It is believed that the centre of the Archaeocyatha origin is now located in East Siberia, where they are first known from the beginning of the Tommotian Age of the Cambrian, 525 million years ago ( mya). In other regions of the world, they appeared much later, during the Atdabanian, and quickly diversified into over a hundred families. They became the planet's very first reef-building animals and are an index fossil for the Lower Cambrian worldwide. Preservation The remains of Archaeocyatha are mostly preserved as carbonate structures in a limestone matrix. This means that the fossils cannot be chemically or mechanically isolated, save for some specimens that have already eroded out of their matrices, and their morphology has to be determined from thin cuts of the stone in which th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Periwinkle (mollusc)
The Littorinidae are a taxonomic family of over 200 species of sea snails, marine gastropod molluscs in the clade Littorinimorpha, commonly known as periwinkles and found worldwide. Names In English-speaking countries, gastropod molluscs from other families, such as the Neritidae, are sometimes also commonly known as "winkles" because they are small, round snails that occupy a similar ecological niche. Taxonomy These subfamilies have been recognized in the taxonomy of Bouchet & Rocroi (2005): * Subfamily Littorininae Children, 1834 – synonyms: Echinininae Rosewater, 1972; Tectariinae Rosewater, 1972; Melaraphidae Starobogatov & Sitnikova, 1983 * Subfamily Lacuninae Gray, 1857 – synonyms: Risellidae Kesteven, 1903; Cremnoconchinae Preston, 1915; Bembiciidae Finlay, 1928. * Subfamily Laevilitorininae Reid, 1989 Genera within the family Littorinidae include: ; Littorininae * ''Afrolittorina'' Williams, Reid & Littlewood, 2003 * '' Austrolittorina'' Rosewater, 1970 * ''C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pleistocene
The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in 2009 by the International Union of Geological Sciences, the cutoff of the Pleistocene and the preceding Pliocene was regarded as being 1.806 million years Before Present (BP). Publications from earlier years may use either definition of the period. The end of the Pleistocene corresponds with the end of the last glacial period and also with the end of the Paleolithic age used in archaeology. The name is a combination of Ancient Greek grc, label=none, πλεῖστος, pleīstos, most and grc, label=none, καινός, kainós (latinized as ), 'new'. At the end of the preceding Pliocene, the previously isolated North and South American continents were joined by the Isthmus of Panama, causing a faunal interchange between the two reg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Misnomer
A misnomer is a name that is incorrectly or unsuitably applied. Misnomers often arise because something was named long before its correct nature was known, or because an earlier form of something has been replaced by a later form to which the name no longer suitably applies. A misnomer may also be simply a word that someone uses incorrectly or misleadingly. The word "misnomer" does not mean " misunderstanding" or " popular misconception", and a number of misnomers remain in common usage — which is to say that a word being a misnomer does not necessarily make usage of the word incorrect. Sources of misnomers Some of the sources of misnomers are: * An older name being retained after the thing named has changed (e.g., tin can, mince meat pie, steamroller, tin foil, clothes iron, digital darkroom). This is essentially a metaphorical extension with the older item standing for anything filling its role. * Transference of a well-known product brand name into a genericized t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phylum
In biology, a phylum (; plural: phyla) is a level of classification or taxonomic rank below kingdom and above class. Traditionally, in botany the term division has been used instead of phylum, although the International Code of Nomenclature for algae, fungi, and plants accepts the terms as equivalent. Depending on definitions, the animal kingdom Animalia contains about 31 phyla, the plant kingdom Plantae contains about 14 phyla, and the fungus kingdom Fungi contains about 8 phyla. Current research in phylogenetics is uncovering the relationships between phyla, which are contained in larger clades, like Ecdysozoa and Embryophyta. General description The term phylum was coined in 1866 by Ernst Haeckel from the Greek (, "race, stock"), related to (, "tribe, clan"). Haeckel noted that species constantly evolved into new species that seemed to retain few consistent features among themselves and therefore few features that distinguished them as a group ("a self-contained un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
