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Nybyoceras
''Nybyoceras'' is an actinocerid genus assigned to the Armenoceratidae and similar to ''Armenoceras'' except for having a siphuncle close to the ventral side of the shell. Morphology As with ''Armenoceras'', ''Nybyoceras'' has a medium to large, straight shell.(Teichert 1964) Its primary diagnostic feature is its ventral siphuncle which the septa across obliquely.(Flower 1957,Teichert 1964) Ventrally, the septal necks are short and free, or recumbent for a short distance. Dorsally the brims are definitely recumbent.(Flower 1957) The connecting rings are broadly adnate to the septa ventrally at the posterior ends of the segments and dorsally at the anterior (adoral) ends.(Teichert 1964) Flower (1957) described the canal system within the siphuncle as being primarily of the single arc type, like ''Armenoceras'', and with interconnecting tubes. Teichert (1964) describes the canal system as being reticulate to curved and branching. Phylogengy and distribution ''Nybyoceras'' is de ... [...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] |
Armenoceras
''Armenoceras'' is a genus of actinocerid nautiloid cephalopods whose fossils ranged from the late Whiterockian Stage in the early Middle Ordovician, through the remainder of the period and on into the Upper Silurian. It is the type genus of the family Armenoceratidae. The shells of ''Armenoceras'' are straight and medium to large in size with a circular to subcircular cross section. The siphuncle is large, located subcentrally to resting on the ventral margin. Segments are wider than long, broadly expanded into the camerae. Septal necks short with wide brings that may be in contact with posterior surface of septa. In most the canal system within the siphuncle in is of the double arc type. Cameral deposits are rare. ''Armenoceras'' is derived from ''Wutinoceras'' through a thinning of the connecting rings and a simplification of the endosiphuncular canal system. The earliest ''Armenoceras'' known comes from the lower Whiterock equivalent in northern China and Korea but is unkn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selkirkoceras
''Selkirkoceras'' is a genus of armonoceratid cephalopods similar to ''Kochoceras'' of the Actinoceratidae, but with recumbent septal necks. The first siphuncular segment is large, broad, and blunt. ''Selkirkoceras'', which is known from the Middle Ordovician of western North America, is included in the '' Nybyoceras'' branch of the 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. Act ... (Teichert, 1964), which also includes ''Nybyoceras'' and '' Megadisocosorus''. References * Curt Teichert, 1964. Actinoceratoidea, Treatise on Invertebrate Paleontology, Part K. Geological Society of America and University of Kansas Press. Prehistoric nautiloid genera Actinocerida {{paleo-nautiloidea-stub ... [...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] |
Megadisocosorus
''Megadisocosorus'' is a genus of actinocerid cephalopods similar to ''Armenoceras'' but with a short, slightly curved, breviconic shell. The siphuncle is in contact with the ventral wall, unlike that of ''Armenoceras'' in which the siphuncle is close to the center. ''Megadisocosorus'' is known from the Middle Silurian of North America. According to Teichert, 1964, ''Megadisocosorus'' is a member of one of the two branches of the Armenoceratidae that also includes ''Nybyoceras'' and ''Selkirkoceras ''Selkirkoceras'' is a genus of armonoceratid cephalopods similar to ''Kochoceras'' of the Actinoceratidae, but with recumbent septal necks. The first siphuncular segment is large, broad, and blunt. ''Selkirkoceras'', which is known from the Mid ...''. References * Curt Teichert, 1964. Actinoceratoidea, Treatise on Invertebrate Paleontology, Part K. Geological Society of America and University of Kansas Press. Prehistoric nautiloid genera Actinocerida {{paleo-nautiloidea ... [...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] |
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] |
Chazyan
The Chazy Reef Formation is a mid-Ordovician limestone deposit in northeastern North America. It consists of some of the oldest reef systems built by a community of organisms rather than the deposit of a limited range of similar organisms, such as Stromatolite mounds deposited by ancient cyanobacteria. The reef structure was formed largely by cryptostome and trepostome bryozoa, some of the oldest known bryozoans, but corals made an early appearance, and stromatoporoids. The formation is named for the small town of Chazy, New York, where the reef was noted by James Hall in ''Palaeontology of New York'' (vol. I, 1847) and the fossils first studied by the Canadian paleontologist Elkanah Billings (1858, 1859). The reef extends from Tennessee to Quebec and Newfoundland, but its most easily studied outcropping is at Goodsell Ridge, Isle La Motte, the northernmost island in Lake Champlain; there, gentle uplift has tilted the sediments: the bedding planes now dip slightly to the north ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prehistoric Cephalopod Genera
Prehistory, also known as pre-literary history, is the period of human history between the use of the first stone tools by hominins 3.3 million years ago and the beginning of recorded history with the invention of writing systems. The use of symbols, marks, and images appears very early among humans, but the earliest known writing systems appeared 5000 years ago. It took thousands of years for writing systems to be widely adopted, with writing spreading to almost all cultures by the 19th century. The end of prehistory therefore came at very different times in different places, and the term is less often used in discussing societies where prehistory ended relatively recently. In the early Bronze Age, Sumer in Mesopotamia, the Indus Valley Civilisation, and ancient Egypt were the first civilizations to develop their own scripts and to keep historical records, with their neighbors following. Most other civilizations reached the end of prehistory during the following Iron Age. ... [...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] |
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