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Spirillinata
The Spirillinata are a group of Foraminifera established by Maslakova, 1990, for spirally wound forms, where the Foraminifera are regarded as a phylum. Two subclasses are included, the agglutinated Ammodiscana and the calcareous Spirillinana. Tests of the Spirillinata consist typically of a proloculus followed by an undivided planospirally or trochospirally wound tubular chamber such that the test is either planar or conical. Some however are pseudochambered as the result of constrictions of the test wall or by short septula (incomplete septa). The two orders are distinguished by their composition. The Ammodiscana are composed of fine agglutinated matter. The Spirillinana, in the original sense, are composed of an optically single crystal of calcite. Genera added from the Involutinida are of aragonite Aragonite is a carbonate mineral, one of the three most common naturally occurring crystal forms of calcium carbonate, (the other forms being the minerals calcite and vat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spirillinata
The Spirillinata are a group of Foraminifera established by Maslakova, 1990, for spirally wound forms, where the Foraminifera are regarded as a phylum. Two subclasses are included, the agglutinated Ammodiscana and the calcareous Spirillinana. Tests of the Spirillinata consist typically of a proloculus followed by an undivided planospirally or trochospirally wound tubular chamber such that the test is either planar or conical. Some however are pseudochambered as the result of constrictions of the test wall or by short septula (incomplete septa). The two orders are distinguished by their composition. The Ammodiscana are composed of fine agglutinated matter. The Spirillinana, in the original sense, are composed of an optically single crystal of calcite. Genera added from the Involutinida are of aragonite Aragonite is a carbonate mineral, one of the three most common naturally occurring crystal forms of calcium carbonate, (the other forms being the minerals calcite and vat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Involutinida
Involutinida is an order of foraminifera included in the Spirillinata found in the fossil record from the early Permian to early Late Cretaceous (Cenomanian). Diagnosis The Involutinida are characterized by a two chambered aragonitic test Test(s), testing, or TEST may refer to: * Test (assessment), an educational assessment intended to measure the respondents' knowledge or other abilities Arts and entertainment * ''Test'' (2013 film), an American film * ''Test'' (2014 film), ... consisting of an initial spheroidal chamber, or proloculus, enclosed by a tubular second, or main chamber. The test wall may be bilamellar (two layered), the inner layer being microgranular and often dark, the outer hyaline (ckear, glassy). Coiling may be planispiral or trochospiral, forming a cone. Lamellar thickenings or pillar-like structures may be found in the umbilical region on one ore both sides. Alfred R. Loeblich Jr & Helen Tappan,1988. Forminiferal Genera and their Classification. Van ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foraminifera
Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular Ectoplasm (cell biology), ectoplasm for catching food and other uses; and commonly an external shell (called a "Test (biology), test") of diverse forms and materials. Tests of chitin (found in some simple genera, and Textularia in particular) are believed to be the most primitive type. Most foraminifera are marine, the majority of which live on or within the seafloor sediment (i.e., are benthos, benthic), while a smaller number float in the water column at various depths (i.e., are planktonic), which belong to the suborder Globigerinina. Fewer are known from freshwater or brackish conditions, and some very few (nonaquatic) soil species have been identified through molecular analysis of small subunit ribosomal DNA. Foraminifera typically produce a test (biology), test, or shell, which can have eithe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian
The Cambrian Period ( ; sometimes symbolized C with bar, 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 Ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eukaryota
Eukaryotes () are organisms whose Cell (biology), cells have a cell nucleus, nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the Three-domain system, three domains of life. Bacteria and Archaea (both prokaryotes) make up the other two domains. The eukaryotes are usually now regarded as having emerged in the Archaea or as a sister of the Asgard (archaea), Asgard archaea. This implies that there are only Two-domain system, two domains of life, Bacteria and Archaea, with eukaryotes incorporated among archaea. Eukaryotes represent a small minority of the number of organisms, but, due to their generally much larger size, their collective global biomass (ecology), biomass is estimated to be about equal to that of prokaryotes. Eukaryotes emerged approximately 2.3–1.8 billion years ago, during the Proterozoic eon, likely as Flagellated cell, flagellated phagotrophs. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SAR Supergroup
The SAR supergroup, also just SAR or Harosa, is a clade that includes stramenopiles (heterokonts), alveolates, and Rhizaria. The name is an acronym derived from the first letters of each of these clades; it has been alternatively spelled "RAS". The term "Harosa" (at the subkingdom level) has also been used. The SAR supergroup is a node-based taxon. Note that as a formal taxon, "Sar" has only its first letter capitalized, while the earlier abbreviation, SAR, retains all uppercase letters. Both names refer to the same group of organisms, unless further taxonomic revisions deem otherwise. Members of the SAR supergroup were once included under the separate supergroups Chromalveolata (Chromista and Alveolata) and Rhizaria, until phylogenetic studies confirmed that stramenopiles and alveolates diverged with Rhizaria. This apparently excluded haptophytes and cryptomonads, leading Okamoto ''et al.'' (2009) to propose the clade Hacrobia to accommodate them. Phylogeny Based on a compi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhizaria
The Rhizaria are an ill-defined but species-rich supergroup of mostly unicellular eukaryotes. Except for the Chlorarachniophytes and three species in the genus Paulinella in the phylum Cercozoa, they are all non-photosynthethic, but many foraminifera and radiolaria have a symbiotic relationship with unicellular algae. A multicellular form, ''Guttulinopsis vulgaris'', a cellular slime mold, has also been described. This group was used by Cavalier-Smith in 2002, although the term "Rhizaria" had been long used for clades within the currently recognized taxon. Being described mainly from rDNA sequences, they vary considerably in form, having no clear morphological distinctive characters (synapomorphies), but for the most part they are amoeboids with filose, reticulose, or microtubule-supported pseudopods. In the absence of an apomorphy, the group is ill-defined, and its composition has been very fluid. Some Rhizaria possess mineral exoskeleton (thecae or loricas), which is in differ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retaria
Retaria is a clade within the supergroup Rhizaria containing the Foraminifera and the Radiolaria. In 2019, the Retaria were recognized as a basal Rhizaria group, as sister of the Cercozoa Cercozoa is a phylum of diverse single-celled eukaryotes. They lack shared morphological characteristics at the microscopic level, and are instead defined by molecular phylogenies of rRNA and actin or polyubiquitin. They were the first major eu .... References External links Taxa named by Thomas Cavalier-Smith SAR supergroup phyla {{Retaria-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Miliolata
Miliollata is a class wherein Foraminifera is regarded as a phylum that unites the porcelaneous Miliolida, (subclass Miliolana Saidova, 1981) and siliceous Rzehakinidae (subclass Miliamminana Mikhalevich, 1980) based on similarities of their tests. Previously the Rzehakinidae were included in the Textulariina (Loeblich and Tappan, 1964) based on test wall composition rather than test form. The meaning of Miliolida is retained. The Miliolana are variable in form. All are porceleneous and iperphorate, some incorporating foreign material; some are attached, others free. Includes the Milliolidae which have two tubular chambers per whorl, the multichambered Sorititdae and the mostly prolate Alveolinidae. The Rzehakinidae (Miliamminana) resemble the Miliolidae in overall form but differ in composition. References Miliolta-Foraminiferai(V.I. Mikhalevich et al.) * Alfred R. Loeblich Jr and Helen Tappan Helen may refer to: People * Helen of Troy, in Greek mythology, the mos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcite
Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on Scratch hardness, scratch hardness comparison. Large calcite crystals are used in optical equipment, and limestone composed mostly of calcite has numerous uses. Other polymorphs of calcium carbonate are the minerals aragonite and vaterite. Aragonite will change to calcite over timescales of days or less at temperatures exceeding 300 °C, and vaterite is even less stable. Etymology Calcite is derived from the German ''Calcit'', a term from the 19th century that came from the Latin word for Lime (material), lime, ''calx'' (genitive calcis) with the suffix "-ite" used to name minerals. It is thus etymologically related to chalk. When applied by archaeology, archaeologists and stone trade pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
