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Wutinoceratidae
The Wutinoceratidae are a family of early actinocerids defined by Shimazu and Obata in 1938Flower 1976. New American Wutinoceratidae with Review of Actinoceroid Occurrences in Eastern Hemisphere;PartI, Memoir 28; New Mexico Bureau of Mines and Mineral Resources for actinocerids with thick connecting rings and a complex irregular canal system. Actinocerids are generally straight shelled nautiloid cephalopods with a siphuncle composed of expanded segments, typically with thin connecting rings, in which the internal deposits are penetrated by a system of canals.Teichert 1964. Actinoceratoidea, Treatise on Invertebrate Paleontology, part K.(Nautiloidea) The Wutinoceratidae include three genera,Flower 1957. Studies of the Actinoceratida. Memoir 2; New Mexico Bureau of Mines and Mineral Resources, Socorro, NM ''Wutinoceras'', ''Cyrtonybyoceras'', and ''Adamsoceras'', known especially from the early Middle Ordovician (Whiterock stage) in northeastern China and North America, but foun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wutinoceras
''Wutinoceras'' is a genus of now extinct nautiloid cephalopods of the Wutinoceratidae family. It exhibits orthoconic actinocerids with ventral siphuncles composed of broadly expanded segments.Memoir 2, Studies of the Actinocerida, New Mexico Bureau of Mines and Mineral ResourcesMemoir 19, The First Great Expansion of the Actinoceroids, New Mexico Bureau of Mines and Mineral Resources Distinguishing characteristics ''Wutinoceras'', as with its family the Wutinoceratidae, has a reticulated canal system within the siphuncle, distinguishing it from later forms with arcuate canal systems. Septal necks, components of the siphuncle that project from the back side of the septa, are cyrtochoanitic (outwardly curved) and may be recumbent. Connecting rings are thick, reflective of the ancestral form. Varieties The three varieties of ''Wutinoceras'' are based on the form of the siphuncle, and each contains a number of species. These have not been ascribed to subgenera. They include th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Actinocerida
The Actinocerida are an order of generally straight, medium to large cephalopods that lived during the early and middle Paleozoic, distinguished by a siphuncle composed of expanded segments that extend into the adjacent chambers, in which deposits formed within contain a system of radial canals and a narrow space along the inner side of the connecting ring known as a paraspatium. (Teichert 1964) Septal necks are generally short and cyrtochoanitic, some being recumbent, some hook shaped. Most grew to lengths of about but some, like the Huroniidae of the Silurian grew significantly larger. Ecology The Actinocerida inhabited shallow to quite deep waters, where they alternated between swimming and lying on the bottom. They were predatory, and able to control their buoyancy to a greater degree than their contemporaries. Derivation The derivation of the Actinocerida remains enigmatic. They first appear late in the Early Ordovician (Cassinian Stage, late Floian) with the Georginida ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyrtonybyoceras
''Cyrtonybyoceras'' is a genus of slightly exogastric members of the Wutinoceratidae, a family of actinocerids and probably derived from an earlier ''Wutinoceras'' . The shell of ''Cyrtonybyoceras'' is curved slightly upwardly and is slightly compressed. Sutures slope toward the aperture, from the dorsum to the venter. The siphuncle is ventral but not marginal, in general form like that of ''Nybyoceras''. Upper and lower septal necks are recumbent or narrowly free. The canal system is reticular, characteristic of the Wutinoceratidae.Flower R.H.,1968;The First Great Expansion of the Actinoceroids, New Mexico Bureau of Mines and Mineral Resources, Memoir 19 Part I, Socorro NM ''Cyrtonybyoceras'' and ''Wutinoceras'' are similar, except for ''Cyrtonybyoceras'' being slightly cyrtoconic, and almost intergrade. ''Cyrtonybyoceras'' is so far known only from the Whiterock Stage in North America. The genotype, ''Cyrtonybyoceras haesitans'', was named by Teichert in 1933, based on ''Orthoc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adamsoceras
''Adamsoceras'' is a genus of actinocerids of the family Wutinoceratidae, with spheroidal siphuncle segments like '' Ormoceras'', but having a reticular canal system like ''Wutinoceras''. Adamsoceras has a slender, gently expanding, orthoconic shell that is slightly broader than high, i.e. depressed, with close spaced septa that form ventral lobes and a siphuncle that is near the ventral margin. ''Adamsoceras'' is known from rocks of Whiterockian age (early Middle Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. T ...) in Nevada, the Baltic, Tasmania, and Manchuria. It may have been derived from ''Wutinoceras'', or from a common ancestor, and gave rise to ''Ormoceras''. The genotype is ''Adamsoceras isabelae'' from the upper Pogonip Group in Ikes Canyon in the Toquima Ran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ordovician
The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. The Ordovician, named after the Celtic Britons, Welsh tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same Rock (geology), rock beds in North Wales in the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed Stratum, strata were different from those of either the Cambrian or the Silurian systems, and placed them in a system of their own. The Ordovician received international approval in 1960 (forty years after Lapworth's death), when it was adopted as an official period of the Paleozoic Era by the International Union of Geological Sciences, Intern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nautiloidea
Nautiloids are a group of marine cephalopods (Mollusca) which originated in the Late Cambrian and are represented today by the living ''Nautilus'' and ''Allonautilus''. Fossil nautiloids are diverse and speciose, with over 2,500 recorded species. They flourished during the early Paleozoic era, when they constituted the main predatory animals. Early in their evolution, nautiloids developed an extraordinary diversity of shell shapes, including coiled morphologies and giant straight-shelled forms ( orthocones). Only a handful of rare coiled species, the nautiluses, survive to the present day. In a broad sense, "nautiloid" refers to a major cephalopod subclass or collection of subclasses (Nautiloidea ''sensu lato''). Nautiloids are typically considered one of three main groups of cephalopods, along with the extinct ammonoids (ammonites) and living coleoids (such as squid, octopus, and kin). While ammonoids and coleoids are monophyletic clades with exclusive ancestor-descendant rela ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siphuncle
The siphuncle is a strand of tissue passing longitudinally through the shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the living nautiluses, cuttlefish, and ''Spirula''. In the case of the cuttlefish, the siphuncle is indistinct and connects all the small chambers of that animal's highly modified shell; in the other cephalopods it is thread-like and passes through small openings in the septa (walls) dividing the camerae (chambers). Some older studies have used the term siphon for the siphuncle, though this naming convention is uncommon in modern studies to prevent confusion with a mollusc organ of the same name. Function The siphuncle is used primarily in emptying water from new chambers as the shell grows. To perform this task, the cephalopod increases the saltiness of the blood in the siphuncle, and the water moves from the more dilute chamber into the blood through osmosis. At the sam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Armenoceratidae
The Armenoceratidae are a family of early Paleozoic nautiloid cephalopods belonging to the order Actinocerida.Flower 1957.Studies of the Actinoceratida.; Memoir 2; New Mexico Bureau of Mines and Mineral Resources, Socorro, NM Teichert 1964. Actinoceratoidea, Treatise on Invertebrate Paleontology, part K.(Nautiloidea) The Armenoceratidae, established by Troedsson (1926) are characterized by large, straight, or slightly curved shells and large siphuncles with strongly expanded segments between the septa. Septal necks are short and abruptly recurved along brims. Radial canals in the endosiphuncular canal system are typically arched, curving forward and backward from near the septal foramina (openings) to connect with the parispatium on either side of the middle of each segments. The parispatium is the narrow opening between the inner side of the connecting rings in actinocerids and the internal siphuncular deposits that grow forward and back from the region of the septal open ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Actinoceras
''Actinoceras'' is the principal and root genus of the Actinoceratidae, a major family in the Actinocerida, that lived during the Middle and Late Ordovician. It is an extinct genus of nautiloid cephalopod that thrived in the warm waters of the United States during the Paleozoic era. Morphology ''Actinoceras'' are generally large, with typically straight shells reaching a meter or so in length (about 3 ft), with a blunt apex, and usually with a circular to subcircular cross section. . Shell characteristics The shells of ''Actinoceras'' are generally straight and long, although some are breviconic. Some are fusiform with the diameter decreasing from the anterior end of the phragmocone toward the aperture. Chambers are short and contain cameral deposits which are more concentrated apically and ventrally. Septa are close spaced, sutures are mostly transverse. The siphuncle, which varies in proportion to the size of the shell among species, is ventral, but not on the ventral ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ordovician Cephalopods
The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. The Ordovician, named after the Welsh tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same rock beds in North Wales in the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed strata were different from those of either the Cambrian or the Silurian systems, and placed them in a system of their own. The Ordovician received international approval in 1960 (forty years after Lapworth's death), when it was adopted as an official period of the Paleozoic Era by the International Geological Congress. Life continued to flourish during the Ordovician as it did in the earlier Cambr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Middle Ordovician First Appearances
Middle or The Middle may refer to: * Centre (geometry), the point equally distant from the outer limits. Places * Middle (sheading), a subdivision of the Isle of Man * Middle Bay (other) * Middle Brook (other) * Middle Creek (other) * Middle Island (other) * Middle Lake (other) * Middle Mountain, California * Middle Peninsula, Chesapeake Bay, Virginia * Middle Range, a former name of the Xueshan Range on Taiwan Island * Middle River (other) * Middle Rocks, two rocks at the eastern opening of the Straits of Singapore * Middle Sound, a bay in North Carolina * Middle Township (other) * Middle East Music * "Middle" (song), 2015 * "The Middle" (Jimmy Eat World song), 2001 * "The Middle" (Zedd, Maren Morris and Grey song), 2018 *"Middle", a song by Rocket from the Crypt from their 1995 album ''Scream, Dracula, Scream!'' *"The Middle", a song by Demi Lovato from their debut album ''Don't Forget'' *"The Middle", a song by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
