Sigmoilina

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Sigmoilina
Temporal range: Early Miocene - Recent.
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Sigmoilina

Schlumberger 1887

Sigmoilina is a miliolid genus, referring to the foraminiferal order Miliolida, characterized by an assymmetricall biconvex test formed by strongly overlapping chambers, one-half coil in length, that form a sigmoid (S-shaped) curve in cross section. The strongly overlapping chambers obliterate earlier ones from view resulting in the compressed biloculine appearance, differing from the squat, depressed biloculine form of Pyrgo and Biloculina . The test, as for all Miliolida, is porcelaneous and imperphorate, the terminal aperture, with tooth, the only point of egress and ingress for the animal.

Sigmoilina is a protist, or proctoctist according to B.K. Sen Gupta, 1999, included in the miliolid family Hauerinidae (Loeblich & Tappan, 1988). It was previously assigned to the Miliolidae (Loeblich & Tappan, 1964) when foraminifera were regarded as comprising a suborder (Foraminiferida).

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<span class="mw-page-title-main">Miliolida</span> Order of single-celled organisms

The Miliolida are an order of foraminifera with calcareous, porcelacous tests that are imperforate and commonly have a pseudochitinous lining. Tests are composed of randomly oriented calcite needles that have a high proportion of magnesium along with organic material. Tests lack pores and generally have multiple chambers.

<span class="mw-page-title-main">Rotaliida</span> Order of single-celled organisms

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.

<span class="mw-page-title-main">Textulariida</span> Order of single-celled organisms

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.

Carterina is a genus in the family Trochamminidae, composing its own subfamily Carterininae. The genus is described from specimens gathered during the Challenger expedition's circumnavigation of the Earth from 1872-1876.

Idalina is a genus of foraminifera included in the Hauerinidae, (Miliolida), that lived during the latter part of the Late Cretaceous.

Miliamellus is a genus of Cenozoic benthic foraminifera with tests made of imperforate opaline silica. It is the only genus in the order Silicoloculinida and the family Silicoloculinidae. It is sometimes referred to by the junior synonym Silicoloculina.

<i>Cibicides</i> Genus of foraminifers

Cibicides is a genus of cosmopolitan benthic foraminifera known from at least as far back as the Paleocene that extends down to the present.

Discorbis is a genus of benthic Foraminifera, that made its first appearance during the Eocene. Its present distribution is cosmopolitan.

Rosalina is a genus of foraminifera included in the rotaliid family Rosalinidae.

Neoconorbina is a genus of recent (Holocene) discorbacean foraminifers related to Rosalina with a low conical trochoidal test, circular in outline. The conical side is the spiral side, on which all three whorls are visible, the final chamber taking up most of the periphery. The umbilical side is flat to concave. exposing only the three to four chambers of the final whorl around an open umbilicus. Chambers on the umbilical side have triangular to platelike umbilical extensions as with other rasalinids. The wall of is calcite, finely and densely perforate on the spiral side, more coarsely perforate on the umbilical side; surface smooth; aperture at the umbilical margin of the chamber, beneath the platelike extension, or folium.

Astrononion is a genus of foraminifera in the family Nonionidae, characterized by an evolute planispiral test with radially stellate structures partly covering the sutures on either side. The test is free, bilaterally symmetrical; periphery broadly rounded; chambers distinct, separated by depressed radial sutures, increasing gradually in size, and usually inflated; aperture a low arched opening at the base of the face of the test. The wall is of finely perforate monolamellar granular calcite.

Globulina is a genus of Foraminifera with an ovate to globular test, included in the Polymorphinidae, Notocariacea, that has been extant since the Middle Jurassic (Callovian).

Triloculina is a genus of foraminifera in the order Miliolida, included in the Quinqueloculininae. The test is three, chambers each a half coil in length. Early chambers, at least in the microspheric generation, in quinqueloculinan arrangement, later becoming triloculine with successive chambers added in planes 120 degrees apart. Only the final three chambers are visible externally. The aperture is terminal, at the end of the final chamber, with a bifid tooth in adult forms. As with the entire order, the test is composed of imperforate, porcelaneous calcite.

Sigmoilinopsis is a genus of miliolid Foraminifera, with an ovate test, chambers one-half coil in length, arranged in rapidly changing planes in the early stage resulting in two spiralling series that appear sigmoid in section, gradually becoming planispiral in the adult. Walls are thick, porcelaneous but enclosing a large quantity of agglutinated quartz particles, sponge spicules, and shell fragments; the aperture terminal, rounded, with a small tooth.

Triloculinella is a genus of Miliolacean forams with a fusiform to asymmetrically globular test. Inner chambers, one-half coil in length, are crypto-quinqueloculine to quinqueloculine in arrangement; The final three to five visible from the exterior. The aperture is an arch at the end of the final chamber, largely covered by a broad apertural flap, which distinguishes the genus from Triloculina, Quinqueloculina and such, characterized by a more narrow tooth. The wall, as for all miliolids, is calcareous, imperforate, porcelaneous.

<span class="mw-page-title-main">Hauerinidae</span> Family of single-celled organisms

Hauerinidae is a large and diverse family of miliolid forams that includes genera distributed among various subfamilies in the Treatise as well as genera named and described since.

<span class="mw-page-title-main">Fischerinidae</span> Family of single-celled organisms

Fischerinidae is a foraminiferal family now in the miliolid superfamily Cornuspiracea that comprises genera that can be free or attached, in which the proloculus is followed by an undivided tubular or spreading second chamber. Commonly, especially in free, i.e. unattached, forms the second chamber is looped around in coils. As diagnostic for the Miliolida the test wall is of imperphorate porcelaneous calcite. The aperture, which is the avenue of egress and ingress for the protoplasm, is terminal; can be rounded or slitlike.

Cornuspiracea comprise a superfamily of miliolid forams in which the test may be free or attached, planispiral or trochospiral, evolute or involute, spreading or discoidal. The proloculus, or initial chamber, is followed by undivided spiral passage or enrolled tubular chamber, later may be irregularly coiled, unicoiled, or show zigzag growth pattern and may be distinctly chambered. The test wall is composed of imperforate porcelaneous calcite, a character of the Miliolida

Miliolana is a subclass established by Saidova, 1981 that comprises porcelaneous members of the Miliolata from the Cornuspirida, Miliolida with agglutinated forms removed to the Miliamminana, and Soritida. Included are both free and attached forms, some coiled with two chambers per whorl arranged in different planes, others that are irregular or have serial chambers, and still others are fusiform with complex interiors, superficially resembling the Fusulinacea. The unifying character is their imperforate porcelaneous tests.

Meandropsinidae is an extinct family of miliolid forams found in Upper Cretaceous (Cenomanian) to middle Paleocene marine sediments.

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