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Atlanta (gastropod)
''Atlanta'' is a genus of pelagic marine gastropod molluscs in the family Atlantidae. They are sometimes called heteropods.Bouchet, P.; Gofas, S. (2012). Atlanta. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=137687 on 2012-07-18 Distribution All of the nineteen species but one, '' Atlanta californiensis'', dwell in tropical and subtropical waters. The majority of species (ten) are cosmopolitan and, among the remaining nine species, five are Indo-Pacific, two are restricted to the Pacific Ocean, one is Indo-Atlantic, and one is limited to the Atlantic Ocean. They are floating or swimming snails in tropical and subtropical seas. Most have a cosmopolitan distribution, but ''A. brunnea'', ''A. pulchella'' and ''A. quoyi'' are only found in American waters. ''A. fusca'', ''A. pacifica'' and ''A. rosea'' are restricted the seas around Japan. Description It has been recognized by several authors that identification of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bartonian
The Bartonian is, in the ICS's geologic time scale, a stage or age in the middle Eocene Epoch or Series. The Bartonian Age spans the time between . It is preceded by the Lutetian and is followed by the Priabonian Age. Stratigraphic definition The Bartonian Stage was introduced by Swiss stratigrapher Karl Mayer-Eymar in 1857. The name derives from the coastal village Barton-on-Sea (part of New Milton) in southern England. The Barton Group, a lithostratigraphic unit from the south English Hampshire Basin, is of Bartonian age. The distinction between group and stage was made in the second part of the 20th century, when stratigraphers saw the need to distinguish between litho- and chronostratigraphy. The base of the Bartonian is at the first appearance of the calcareous nanoplankton species ''Reticulofenestra reticulata''. In 2009, an official reference profile (GSSP) for the base of the Bartonian had not yet been established. The top of the Bartonian Stage (the ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operculum (gastropod)
The operculum (; ) is a corneous or calcareous anatomical structure like a trapdoor that exists in many (but not all) groups of sea snails and freshwater snails, and also in a few groups of land snails; the structure is found in some marine and freshwater gastropods, and in a minority of terrestrial gastropods, including the families Helicinidae, Cyclophoridae, Aciculidae, Maizaniidae, Pomatiidae, etc. The operculum is attached to the upper surface of the foot and in its most complete state, it serves as a sort of "trapdoor" to close the aperture of the shell when the soft parts of the animal are retracted. The shape of the operculum varies greatly from one family of gastropods to another. It is fairly often circular, or more or less oval in shape. In species where the operculum fits snugly, its outline corresponds exactly to the shape of the aperture of the shell and it serves to seal the entrance of the shell. Many families have opercula that are reduced in size, and which a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atlanta Frontieri
Atlanta ( ) is the capital and most populous city of the U.S. state of Georgia. It is the seat of Fulton County, the most populous county in Georgia, but its territory falls in both Fulton and DeKalb counties. With a population of 498,715 living within the city limits, it is the eighth most populous city in the Southeast and 38th most populous city in the United States according to the 2020 U.S. census. It is the core of the much larger Atlanta metropolitan area, which is home to more than 6.1 million people, making it the eighth-largest metropolitan area in the United States. Situated among the foothills of the Appalachian Mountains at an elevation of just over above sea level, it features unique topography that includes rolling hills, lush greenery, and the most dense urban tree coverage of any major city in the United States. Atlanta was originally founded as the terminus of a major state-sponsored railroad, but it soon became the convergence point among several railro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atlanta Fragilis
''Atlanta fragilis'' is a species of sea snail, a holoplanktonic marine gastropod mollusk in the family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ... Atlantidae. Distribution Description The maximum recorded shell length is 3 mm.Welch J. J. (2010). "The "Island Rule" and Deep-Sea Gastropods: Re-Examining the Evidence". '' PLoS ONE'' 5(1): e8776. . Habitat Minimum recorded depth is 30 m. Maximum recorded depth is 250 m. References Atlantidae Gastropods described in 1993 {{Atlantidae-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atlanta Echinogyra
''Atlanta echinogyra'' is a species of sea snail, a holoplanktonic marine gastropod mollusk in the family Atlantidae. Description ''Atlanta echinogyra'' was described in 1972 by Dr. Gotthard Richter (from Senckenberg Museum, Frankfurt am Main, Germany) based on specimens collected during the Meteor Expedition to the northern Indian Ocean. Richter named the species after the unique structure of the opercular gyre, with its raised spiral row of spines. ''Atlanta echinogyra'' is a small species (to 2.5 mm shell diameter). The shell is colorless, although the tissues underlying the shell spire give it a red-violet to red-brown color. The spire is low conical and consists of 3-3.25 whorls. The spire whorls have incised sutures and bear low spiral ridges on the second through most of the fourth whorls. The outer edge of the third and fourth whorls have a raised ridge (seen best in the larval shell). The fourth whorl (first teleoconch whorl) increases rapidly in width and bears ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atlanta Brunnea
''Atlanta brunnea'' is a species of sea snail, a holoplanktonic marine gastropod mollusk in the family Atlantidae. Description ''Atlanta brunnea'' is a small species (shell diameter to 2.0 mm) that is darkly pigmented (brown to reddish-and golden-brown). The keel is tall and colorless, and inserts between the last and penultimate shell whorls in animals larger than 1.5 mm. The spire is tall and conical, consisting of 4 whorls and possessing a complex pattern of spiral sculpture that ends on the protoconch and is replaced by spiral rows of small punctae on the teleoconch. Coloration ranges from brown to amber and reddish brown. Juveniles of this species are easily recognised by their shape and ornament. The protoconch is rather high conical and has 3½ - 3¾ whorls, slowly increasing in diameter. On the first whorl, in front of the nucleus, an ornament is seen of some nine or ten irregular spirals. Two stronger spirals from the second whorl on delimit a subsutural zone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atlanta Arenularia
Atlanta ( ) is the capital and most populous city of the U.S. state of Georgia. It is the seat of Fulton County, the most populous county in Georgia, but its territory falls in both Fulton and DeKalb counties. With a population of 498,715 living within the city limits, it is the eighth most populous city in the Southeast and 38th most populous city in the United States according to the 2020 U.S. census. It is the core of the much larger Atlanta metropolitan area, which is home to more than 6.1 million people, making it the eighth-largest metropolitan area in the United States. Situated among the foothills of the Appalachian Mountains at an elevation of just over above sea level, it features unique topography that includes rolling hills, lush greenery, and the most dense urban tree coverage of any major city in the United States. Atlanta was originally founded as the terminus of a major state-sponsored railroad, but it soon became the convergence point among several railr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atlanta Selvagensis
''Atlanta selvagensis'' is a species of sea snail, a holoplanktonic marine gastropod mollusk in the family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ... Atlantidae. References Atlantidae Gastropods described in 2006 {{Atlantidae-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Recrystallization (geology)
In geology, solid-state recrystallization is a metamorphic process that occurs under high temperatures and pressures where atoms of minerals are reorganized by diffusion and/or dislocation glide. During this process, the physical structure of the minerals is altered while the composition remains unchanged. This is in contrast to metasomatism, which is the chemical alteration of a rock by hydrothermal and other fluids. Solid-state recrystallization can be illustrated by observing how snow recrystallizes to ice. When snow is subjected to varying temperatures and pressures, individual snowflakes undergo a physical transformation but their composition remains the same. Limestone is a sedimentary rock that undergoes metamorphic recrystallization to form marble, and clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operculum (gastropod)
The operculum (; ) is a corneous or calcareous anatomical structure like a trapdoor that exists in many (but not all) groups of sea snails and freshwater snails, and also in a few groups of land snails; the structure is found in some marine and freshwater gastropods, and in a minority of terrestrial gastropods, including the families Helicinidae, Cyclophoridae, Aciculidae, Maizaniidae, Pomatiidae, etc. The operculum is attached to the upper surface of the foot and in its most complete state, it serves as a sort of "trapdoor" to close the aperture of the shell when the soft parts of the animal are retracted. The shape of the operculum varies greatly from one family of gastropods to another. It is fairly often circular, or more or less oval in shape. In species where the operculum fits snugly, its outline corresponds exactly to the shape of the aperture of the shell and it serves to seal the entrance of the shell. Many families have opercula that are reduced in size, and which a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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