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Lotagnostus
''Lotagnostus'' is a genus of very small trilobites in the order Agnostida, which lived on the outer continental shelves worldwide, during the late Upper Cambrian. It was described by Whitehouse in 1936, and the type species is ''Lotagnostus trisectus'', which was originally described as a species of ''Agnostus'' by Salter in 1864. Taxonomy The Treatise on Invertebrate Paleontology divides ''Lotagnostus'' into three subgenera that differ in the degree of effacement: ''L. (Lotagnostus)'' Whitehouse, 1936 (neither cephalon nor pygidium strongly effaced), ''L. (Distagnostus)'' Shergold, 1972 (strongly effaced on the outer/dorsal surface, but with clear furrows on the inner/ventral surface and ''L. (Eolotagnostus)'' Zhou ''in'' Zhiqiang Zhou, li & Qu, 1982 (with even the inner/ventral surface strongly effaced). Later authors however consider it likely that creating these subgenera would render the nominate subgenus paraphyletic. Biostratographic significance The first appearance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agnostus
''Agnostus'' is a genus of agnostid trilobites, belonging to the family Agnostidae, that lived during the late Middle Cambrian – early Upper Cambrian (about 506 to 492 million years ago). It is the type genus of the family Agnostidae and is subdivided into two subgenera, ''Agnostus'' and ''Homagnostus''. Etymology ''Agnostus'' is from the Ancient Greek άγνωστος (''ágnostos'') "unknown", and reflects the fact that early paleontologists did not know what type of animal with which they were confronted. The species epithet has this origin: * ''pisiformis'' derives from the Latin ''pīsum'' which means "pea", and ''forma'' meaning "shape", for its globe-like appearance when rolled. Description ] Like all Agnostida, ''Agnostus'' is diminutive and the headshield (or Cephalon (arthropod head)#Trilobites, cephalon) and tailshield (or pygidium) are around the same size (or isopygous) and outline. As in all Agnostina, ''Agnostus'' has two thorax segments. When Agnostina are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian Stage 10
Stage 10 of the Cambrian is the still unnamed third and final stage of the Furongian series. It follows the Jiangshanian and precedes the Ordovician Tremadocian Stage. The proposed lower boundary is the first appearance of the trilobite ''Lotagnostus americanus'' around million years ago, but other fossils are also being discussed ( see below). The upper boundary is defined as the appearance of the conodont ''Iapetognathus fluctivagus'' which marks the beginning of the Tremadocian and is radiometrically dated as million years ago. Naming The 10th stage of the Cambrian has not been formally named by the ICS yet, although a number of local names exist. Several authors favor the name "Lawsonian" after Lawson Cove, in the Wah Wah Mountains of Utah. The lower part of the North American Skullrockian Stage corresponds roughly to the Cambrian Stage 10. Stratotype The ICS is still discussing which geological section and biostratigraphic marker will be used to define the base of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John William Salter
John William Salter (15 December 1820 – 2 December 1869) was an English naturalist, geologist, and palaeontologist. Salter was apprenticed in 1835 to James De Carle Sowerby, and was engaged in drawing and engraving the plates for Sowerby's ''Mineral Conchology'', the ''Supplement to Sowerby's English Botany'', and other natural history works. In 1842, he was employed for a short time by Adam Sedgwick in arranging the fossils in the Woodwardian Museum at Cambridge, and he accompanied the professor on several geological expeditions (1842–1845) into Wales. Salter was born in Pratt Place, Camden Town, the son of John Salter (1779–1837), a banking clerk, and his wife, Mary Ann. His birth was registered at Dr. William's Library near Cripplegate, London. In 1846, Salter married Sally, daughter of James De Carle Sowerby, and eventually fathered seven children with her. Also in 1846, Salter was appointed on the staff of the Geological Survey and worked under Edward Forbes until 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agnostidae
Agnostidae is a family of Agnostida trilobites. Like all Agnostina, they were eyeless and bore only two thoracic segments. They ranged in benthic waters across the globe from 508 to 461 million years ago, containing the following genera, among others: *''Acmarhachis'' *'' Agnostus'' *'' Aistagnostus'' *''Anglagnostus'' *''Biciragnostus'' *''Connagnostus'' *''Distagnostus'' *''Eolotagnostus'' *''Gymnagnostus'' *''Homagnostus'' *''Idolagnostus'' *''Innitagnostus'' *''Ivshinagnostus'' *''Kymagnostus'' *''Lotagnostus'' *''Micragnostus'' *''Obelagnostus'' *''Oncagnostus'' *''Peronopsis'' *''Phalacroma'' *''Phalagnostus'' *''Quadrahomagnostus ''Quadrahomagnostus'' is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. They lived from 501 to 490 million years ago during the Dresbachian faunal stage of the late Cambrian period The Cambrian Period ...'' *'' Raragnostus'' *'' Semagnostus'' *'' Strictagnostus'' *'' Trilobagnostus'' References ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sunwaptan
The Cambrian Period ( ; sometimes symbolized Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago (mya) to the beginning of the Ordovician Period mya. Its subdivisions, and its base, are somewhat in flux. The period was established as "Cambrian series" by Adam Sedgwick, who named it after Cambria, the Latin name for 'Cymru' (Wales), where Britain's Cambrian rocks are best exposed. Sedgwick identified the layer as part of his task, along with Roderick Murchison, to subdivide the large "Transition Series", although the two geologists disagreed for a while on the appropriate categorization. The Cambrian is unique in its unusually high proportion of sedimentary deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells. As a result, our understanding of the Cambrian biol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
White Leaved Oak Shale
White is the lightest color and is achromatic (having no hue). It is the color of objects such as snow, chalk, and milk, and is the opposite of black. White objects fully reflect and scatter all the visible wavelengths of light. White on television and computer screens is created by a mixture of red, blue, and green light. The color white can be given with white pigments, especially titanium dioxide. In ancient Egypt and ancient Rome, priestesses wore white as a symbol of purity, and Romans wore white togas as symbols of citizenship. In the Middle Ages and Renaissance a white unicorn symbolized chastity, and a white lamb sacrifice and purity. It was the royal color of the kings of France, and of the monarchist movement that opposed the Bolsheviks during the Russian Civil War (1917–1922). Greek and Roman temples were faced with white marble, and beginning in the 18th century, with the advent of neoclassical architecture, white became the most common color of new churches ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chesley Drive Group for artistic achievement in science fiction and fantasy art
{{disambiguation, geo ...
Chesley can refer to: Places * Chesley, Ontario, Canada, a community * Chesley, Aube, France, a commune * 12104 Chesley, an asteroid Others * Chesley (name) * Chesley Awards The Chesley Awards were established in 1985 by the Association of Science Fiction and Fantasy Artists to recognize individual artistic works and achievements during a given year. The Chesleys were initially called the ASFA Awards, but were later r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eoconodontus
''Eoconodontus'' is an extinct genus of conodonts of the Late Cambrian. It is a two-elements (rounded and compressed) genus from the '' Proconodontus'' lineage. Use in stratigraphy It is suggested that ''Eoconodontus notchpeakensis'' can be a marker of the Stage 10 of the Furongian the fourth and final series of the Cambrian. In 2006, a working group proposed the first appearance of '' Cordylodus andresi''. Currently the first appearance of ''E. notchpeakensis'' is favored by many authors because it is globally widespread and is independent of facies In geology, a facies ( , ; same pronunciation and spelling in the plural) is a body of rock with specified characteristics, which can be any observable attribute of rocks (such as their overall appearance, composition, or condition of formatio ... (known from continental rise to peritidal environments).Landing, E.; Westrop, S.R.; Adrain, J.M. (19 September 2011). "The Lawsonian Stage - the Eoconodontus notchpeakensis FAD and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cordylodus
''Cordylodus'' is an extinct genus of conodonts in the family of Cordylodontidae. Use in stratigraphy It is suggested that ''Cordylodus andresi'' can be a marker of the Cambrian Stage 10. Distribution Fossils of ''Cordylodus'' have been found in Argentina, Australia, Canada (Quebec), China, Colombia ( Tarqui, Huila),Moreno et al., 2008, p.10 Kazakhstan, Malaysia, Mexico, Norway, the Russian Federation, Sweden, and the United States, in the states of Alaska, Minnesota, Nevada, New York, Oklahoma ( Bromide Formation), Vermont and Wyoming. ''C. horridus'' has been recovered from the Blakely Sandstone The Blakely Sandstone is a Middle Ordovician geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. First described in 1892, this unit was not named until 1909 by Albert Homer Purdue in his study of the Ouachita Mountains of Arkans ... and ''C. angulatus'' from the Collier Shale, Ordovician geologic formations in the Ouachita Mountains of Arkansas and Oklaho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Index Fossil
Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them.Hine, Robert. “Biostratigraphy.” ''Oxford Reference: Dictionary of Biology'', 8th ed., Oxford University Press, 2019. The primary objective of biostratigraphy is ''correlation'', demonstrating that a particular horizon in one geological section represents the same period of time as another horizon at a different section. Fossils within these strata are useful because sediments of the same age can look completely different, due to local variations in the sedimentary environment. For example, one section might have been made up of clays and marls, while another has more chalky limestones. However, if the fossil species recorded are similar, the two sediments are likely to have been laid down around the same time. Ideally these fossils are used to help identify biozones, as they make up the basic biostratigraphy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymorphism (biology)
In biology, polymorphism is the occurrence of two or more clearly different morphs or forms, also referred to as alternative ''phenotypes'', in the population of a species. To be classified as such, morphs must occupy the same habitat at the same time and belong to a panmictic population (one with random mating). Ford E.B. 1965. ''Genetic polymorphism''. Faber & Faber, London. Put simply, polymorphism is when there are two or more possibilities of a trait on a gene. For example, there is more than one possible trait in terms of a jaguar's skin colouring; they can be light morph or dark morph. Due to having more than one possible variation for this gene, it is termed 'polymorphism'. However, if the jaguar has only one possible trait for that gene, it would be termed "monomorphic". For example, if there was only one possible skin colour that a jaguar could have, it would be termed monomorphic. The term polyphenism can be used to clarify that the different forms arise from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
