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Foraminifera are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular ectoplasm for catching food and other uses; and commonly an external shell of diverse forms and materials. Tests of chitin are believed to be the most primitive type. Most foraminifera are marine, the majority of which live on or within the seafloor sediment, while a smaller number float in the water column at various depths. 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.
Ismailia is a genus of foraminifera with an agglutinated, planispirally coiled, semi-involute shell, known from the Egyptian Sinai, that lived during the early part of the Late Cretaceous (Cenomanian). Agglutinated shells are composed of selected foreign material cemented together.
The Allogromiida is an order of single-chambered, mostly organic-walled foraminiferans, including some that produce agglutinated tests (Lagynacea). Genetic studies indicate that some foraminiferans with agglutinated tests, previously included in the Textulariida or as their own order Astrorhizida, may also belong here. Allogromiids produce relatively simple tests, usually with a single chamber, similar to those of other protists such as Gromia. They are found as both marine and freshwater forms, and are the oldest forms known from the fossil record.
The Rotaliida are an order of Foraminifera, characterized by multilocular tests (shells) composed of bilamellar perforate hyaline lamellar calcite that may be optically radial or granular.
The Textulariida are an order of foraminifera that produce agglutinated shells or tests. An agglutinated test is one made of foreign particles glued together with an organic or calcareous cement to form an external shell on the outside of the organism. Commonly, the order had been made up of all species of Foraminifera with these types of shells, but genetic studies indicate these organisms do not form an evolutionary group, and several superfamilies in the order have been moved to the order Allogromiida. The remaining forms are sometimes divided into three orders: the Trochamminida and Lituolida, which have organic cement, and the Textulariida sensu stricto, which use a calcareous cement. All three orders or superfamilies are known as fossils from the Cambrian onwards.
Platysolenites is a genus of agglutinated foraminifera known from Ediacaran and lower Cambrian assemblages.
Carterinida is an order of multi-chambered foraminifera within the Globothalamea. Members of this order form hard tests out of thin calcite rods known as spicules, which are held together by a proteinaceous matrix.
Hantkeninoidea is a superfamily of foraminifera with planispiral or enrolled biserial tests, found in marine sediments of Paleocene to Miocene age, in which chambers vary from globular to elongate and the primary aperture is equatorial in position. It contains one family, the Hantkeninidae.
The Foraminiferal Colouration Index (FCI) is a tool for assessing the thermal alteration of organic matter buried in sedimentary rock. It uses temperature-controlled colour changes in the organic cement of agglutinated foraminifera (microfossils) to estimate thermal alteration. The method is empirical and based on determination of colour by visual comparison of fossil specimens to the Geological Society of America Rock-Color Chart under a binocular microscope.
The Cassidulinacea is a superfamily of benthic amoeboid foraminifera in the order Rotaliida that has been extant from the Paleocene down to the present. Tests are composed of secreted, optically radial or granular, perforate calcite with chambers biserially coiled at least in the early part, Apertures are usually an interiomarginal slit, but may become terminal and may have secondary features.
The Pseudogaudryinidae is a family of Late Cretaceous to recent benthic aggultinated Foraminifera included in the Textulariida. Tests are elongate with an early triserial stage, later reduced to biserial or uniserial. Walls are of agglutinated material and are canaliculate, that is have micro-tubular cavities. Apertures, an interiomarginal arch. The Pseudogaudryinidae differs from the Verneuilinidae in the canaliculate wall and from the Valvulinidae in having a simple aperture with-out a tooth.
The Buliminida is an order of mostly benthic foraminifera with tests commonly of perforate, hyaline, radially laminated calcite, with chambers arranged biserially or triserially, at least in the early stages. Superfamilies include the Bolivinacea, Buliminacea, Eouvigerinacea, and Turrilinacea.
Rotaliata is a class of Foraminifera characterized by tests that are exclusively multichambered, mostly planospiral or trochspiral, or derived from either. The aperture is commonly at the base of the apertural face, at least in early stages, but may be terminal, and single or complex. Test interior may be complex with secondary chambers and interconnecting canal system.
Globigerinana are free living pelagic foraminiferan, included in the class Rotaliata that range from the Jurassic to recent. Test are commonly planospiral or trochospiral but may be uniserial to multiserial and are of secreted hyaline (glassy) calcite. Chambers are flattened in planospiral forms and spheroidal in trochospiral and serial forms. Some have long radial spines, or needles that may be solidly fixed or moveable in sockets. Gametes are biflagellate and are produced in greater number than by bottom dwelling benthic forms.
Miliamminana is a subclass of miliolates established by Mikhalevich, 1980 that combines two groups of foraminifers with agglutinated tests. They are the Rzehakinidae which previously were included in the Texulariina in the Treatise on Invertebrate Paleontology although milioline in form, and the milioline Schlumbergerinida which includes genera removed from the Miliolina. The rzehakinids are composed of finely agglutinated material, insoluble in acid, over an organic base. Schlumbergerinids are composed of acid soluble agglutinated material over a porcelenous base. The unifying character is the nature of their coiling in which there are two tubular chambers, or sections, per whorl arranged in various planes and the fact that they are in part all agglutinated.
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.
Tubothalamea is a taxonomic class established for foraminiferans with tubular chambers. Includes the porcelaceous and agglutinated Miliolida and the monocrystalline and agglutinated Spirillinida. It is one of two classes of multichambered foraminifera based on SSU rDNA molecular studies with consideration of major morphological trands, the other being the Globothalamea.
Globothalamea comprises a class of multichambered foraminifera based in part on SSU rDNA evidence; the other is Tubothalamea.
"Monothalamea" is a grouping of foraminiferans, traditionally consisting of all foraminifera with single-chambered tests. Recent work has shown that the grouping is paraphyletic, and as such does not constitute a natural group; nonetheless, the name "monothalamea" continues to be used by foraminifera workers out of convenience.
Heterohelicoidea is a superfamily of middle Jurassic to Oligocene planktonic forams characterized by biserial or triserial tests, at least in the early stage, that may be reduced in the later stage but more commonly show chamber proliferation in the later stage. Aperture a low or high arch at the base of the final chamber or terminal in uniserial stage. Heterohelicoidea contains one family, the Heterohelicidae.
References
- Textulariacea in Loeblich and Tappan, 1988, Foraminferal genera and their classification
- Gupta, Barun K. Sen (2002). Modern Foraminifera. Springer. pp. 16–. ISBN 978-1-4020-0598-5.