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Spironema (gastropod)
†''Spironema'' is a genus of extinct (Cretaceous) sea snails, marine gastropod mollusks in the family Naticidae, the moon snails.Siemers C. T. & King N. R. (1974). "Macroinvertebrate paleoecology of a transgressive marine sandstone, Cliff House Sandstone (Upper Cretaceous), Chaco Canyon, northwestern New Mexico". ''New Mexico Geol. Soc. Guidebook'', 25th Field Conf., Ghost Ranch (Central-Northern N.M.): 267-277PDF Description The American paleontologist Fielding Bradford Meek firstly defined this genus in 1864. He classified the genus in the family Littorinidae. He recognized two species '' Spironema bella'' and '' Spironema tenuilineata'' in 1864. These species were previously classified within the family Trochidae. Meek's diagnosis reads as follows: Species Species within the genus ''Spironema'' include: * '' Spironema bella'' (Conrad) - synonym: ''Tuba'' (?) ''bella'' Conrad, from Cretaceous of Alabama * '' Spironema tenuilineata'' (Meek & Hayden, 1856) - from Cretaceou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal
Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motility, able to move, can Sexual reproduction, reproduce sexually, and go through an ontogenetic stage in which their body consists of a hollow sphere of Cell (biology), cells, the blastula, during Embryogenesis, embryonic development. Over 1.5 million Extant taxon, living animal species have been Species description, described—of which around 1 million are Insecta, insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from to . They have Ecology, complex interactions with each other and their environments, forming intricate food webs. The scientific study of animals is known as zoology. Most living animal species are in Bilateria, a clade whose members have a Symmetry in biology#Bilate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Littorinidae
The Littorinidae are a taxonomic family of over 200 species of sea snails, marine gastropod molluscs in the clade Littorinimorpha, commonly known as periwinkles and found worldwide. Names In English-speaking countries, gastropod molluscs from other families, such as the Neritidae, are sometimes also commonly known as "winkles" because they are small, round snails that occupy a similar ecological niche. Taxonomy These subfamilies have been recognized in the taxonomy of Bouchet & Rocroi (2005): * Subfamily Littorininae Children, 1834 – synonyms: Echinininae Rosewater, 1972; Tectariinae Rosewater, 1972; Melaraphidae Starobogatov & Sitnikova, 1983 * Subfamily Lacuninae Gray, 1857 – synonyms: Risellidae Kesteven, 1903; Cremnoconchinae Preston, 1915; Bembiciidae Finlay, 1928. * Subfamily Laevilitorininae Reid, 1989 Genera within the family Littorinidae include: ; Littorininae * ''Afrolittorina'' Williams, Reid & Littlewood, 2003 * ''Austrolittorina'' Rosewater, 1970 * ''Cenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maastrichtian
The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval from . The Maastrichtian was preceded by the Campanian and succeeded by the Danian (part of the Paleogene and Paleocene). The Cretaceous–Paleogene extinction event (formerly known as the Cretaceous–Tertiary extinction event) occurred at the end of this age. In this mass extinction, many commonly recognized groups such as non-avian dinosaurs, plesiosaurs and mosasaurs, as well as many other lesser-known groups, died out. The cause of the extinction is most commonly linked to an asteroid about wide colliding with Earth, ending the Cretaceous. Stratigraphic definitions Definition The Maastrichtian was introduced into scientific literature by Belgian geologist André Hubert Dumont in 1849, after studying rock strata of the Chalk Group c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spironema Perryi
''Spironema'' may refer to: Animals: * ''Spironema'' (gastropod), ''Spironema'' Meek, 1864 – a genus of Cretaceous sea snails Plants: *''Spironema'' Raf. 838– sometimes considered a synonym of ''Cassytha'' L. (Lauraceae) *''Spironema'' Lindl. 840nom. illeg. hom. – a synonym of ''Callisia'' Loefl. (Commelinaceae) *''Spironema'' Hochst. 842nom. illeg. hom. – a synonym of ''Clerodendrum'' L. (Lamiaceae) Protists: * ''Spironema'' (flagellate), ''Spironema'' Klebs, 1893 – a genus of flagellate protists in the family Spironemidae, possibly a synonym of ''Spironematella'' P. C. Silva Spirochaetes: *''Spironema'' Vuillemin, 1905 – a synonym of ''Treponema ''Treponema'' is a genus of spiral-shaped bacteria. The major treponeme species of human pathogens is ''Treponema pallidum'', whose subspecies are responsible for diseases such as syphilis, bejel, and yaws. ''Treponema carateum'' is the cause o ...'' Schaudinn, 1905 Microsporidia: *''Spironema'' Léger & Hesse, 1924 â ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proceedings Of The Academy Of Natural Sciences Of Philadelphia
The ''Proceedings of the Academy of Natural Sciences of Philadelphia'' is a peer-reviewed scientific journal published by Academy of Natural Sciences of Drexel University The Academy of Natural Sciences of Drexel University, formerly the Academy of Natural Sciences of Philadelphia, is the oldest natural science research institution and museum in the Americas. It was founded in 1812, by many of the leading natura ... since 1841. References External links Publications established in 1841 Academic journals published in the United States Drexel University {{sci-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dakota Territory
The Territory of Dakota was an organized incorporated territory of the United States that existed from March 2, 1861, until November 2, 1889, when the final extent of the reduced territory was split and admitted to the Union as the states of North and South Dakota. History The Dakota Territory consisted of the northernmost part of the land acquired in the Louisiana Purchase in 1803, as well as the southernmost part of Rupert's Land, which was acquired in 1818 when the boundary was changed to the 49th parallel. The name refers to the Dakota branch of the Sioux tribes which occupied the area at the time. Most of Dakota Territory was formerly part of the Minnesota and Nebraska territories. When Minnesota became a state in 1858, the leftover area between the Missouri River and Minnesota's western boundary fell unorganized. When the Yankton Treaty was signed later that year, ceding much of what had been Sioux Indian land to the U.S. Government, early settlers formed a provisiona ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Umbilicus (mollusc)
The umbilicus of a shell is the axially aligned, hollow cone-shaped space within the whorls of a coiled mollusc shell. The term umbilicus is often used in descriptions of gastropod shells, i.e. it is a feature present on the ventral (or under) side of many (but not all) snail shells, including some species of sea snails, land snails, and freshwater snails. The word is also applied to the depressed central area on the planispiral coiled shells of ''Nautilus'' species and fossil ammonites. (These are not gastropods, but shelled cephalopods.) In gastropods The spirally coiled whorls of gastropod shells frequently connect to each other by their inner sides, during the natural course of its formation. This results in a more or less solid central axial pillar, known as the columella. The more intimate the contact between the concave side of the whorls is, the more solid the columella becomes. On the other hand, if this connection is less intense, a hollow space inside the whorls may re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Columella (gastropod)
The columella (meaning "little column") or (in older texts) pillar is a central anatomical feature of a coiled snail shell, a gastropod shell. The columella is often only clearly visible as a structure when the shell is broken, sliced in half vertically, or viewed as an X-ray image. The columella runs from the apex of the shell to the midpoint of the undersurface of the shell, or the tip of the siphonal canal in those shells which have a siphonal canal. If a snail shell is visualized as a cone of shelly material which is wrapped around a central axis, then the columella more or less coincides spatially with the central axis of the shell. In the case of shells that have an umbilicus, the columella is a hollow structure. The columella of some groups of gastropod shells can have a number of plications or folds (the columellar fold, plaits or plicae), which are usually visible when looking to the inner lip into the aperture of the shell. These folds can be wide or narrow, prominent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aperture (mollusc)
The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where the head-foot part of the body of the animal emerges for locomotion, feeding, etc. The term ''aperture'' is used for the main opening in gastropod shells, scaphopod shells, and also for ''Nautilus'' and ammonite shells. The word is not used to describe bivalve shells, where a natural opening between the two shell valves in the closed position is usually called a ''gape''. Scaphopod shells are tubular, and thus they have two openings: a main anterior aperture and a smaller posterior aperture. As well as the aperture, some gastropod shells have additional openings in their shells for respiration; this is the case in some Fissurellidae (keyhole limpets) where the central smaller opening at the apex of the shell is called an orifice, and in the Haliotidae (abalones) where the row of respiratory openings in the shell are also called orifices. In gastropods In some prosobranch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Suture (gastropod)
In anatomy, a suture is a fairly rigid joint between two or more hard elements of an organism, with or without significant overlap of the elements. Sutures are found in the skeletons or exoskeletons of a wide range of animals, in both invertebrates and vertebrates. Sutures are found in animals with hard parts from the Cambrian period to the present day. Sutures were and are formed by several different methods, and they exist between hard parts that are made from several different materials. Vertebrate skeletons The skeletons of vertebrate animals (fish, amphibians, reptiles, birds, and mammals) are made of bone, in which the main rigid ingredient is calcium phosphate. Cranial sutures The skulls of most vertebrates consist of sets of bony plates held together by cranial sutures. These sutures are held together mainly by Sharpey's fibers which grow from each bone into the adjoining one. Sutures in the ankles of land vertebrates In the type of crurotarsal ankle which is found i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Whorl (mollusc)
A whorl is a single, complete 360° revolution or turn in the spiral growth of a mollusc shell. A spiral configuration of the shell is found in numerous gastropods, but it is also found in shelled cephalopods including ''Nautilus'', ''Spirula'' and the large extinct subclass of cephalopods known as the ammonites. A spiral shell can be visualized as consisting of a long conical tube, the growth of which is coiled into an overall helical or planispiral shape, for reasons of both strength and compactness. The number of whorls which exist in an adult shell of a particular species depends on mathematical factors in the geometric growth, as described in D'Arcy Wentworth Thompson's classic 1917 book ''On Growth and Form'', and by David Raup. The main factor is how rapidly the conical tube expands (or flares-out) over time. When the rate of expansion is low, such that each subsequent whorl is not that much wider than the previous one, then the adult shell has numerous whorls. When the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gastropod Shell
The gastropod shell is part of the body of a Gastropoda, gastropod or snail, a kind of mollusc. The shell is an exoskeleton, which protects from predators, mechanical damage, and dehydration, but also serves for muscle attachment and calcium storage. Some gastropods appear shell-less (slugs) but may have a remnant within the mantle, or in some cases the shell is reduced such that the body cannot be retracted within it (semi-slug). Some snails also possess an operculum that seals the opening of the shell, known as the Aperture (mollusc), aperture, which provides further protection. The study of mollusc shells is known as conchology. The biological study of gastropods, and other molluscs in general, is malacology. Shell morphology terms vary by species group. Shell layers The gastropod shell has three major layers secreted by the Mantle (mollusc), mantle. The calcareous central layer, tracum, is typically made of calcium carbonate precipitated into an organic matrix known as c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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