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Strandoceras
''Strandoceras'' is a strongly curved cyrtogomphoceratid with a laterally compressed cross section from the middle and upper Ordovician of Northern Europe; Estonia, Norway, the U.K. The body chamber of ''Stradoceras'' is straighter and more slender than the chambered phragmocone; the venter narrowly rounded with a shallow hyponomic sinus; the aperture open, sutures with shallow lateral lobes. The siphuncle is close to the venter which is on the inside, endogastric curvature. Segments are large and broadly rounded; connecting rings thick, bullettes large. ''Strandoceras'' gave rise to the Phragmoceratidae and very likely to '' Kiaeroceras'' and '' Cyrtogomphoceras'', which in turn gave rise to '' Landeroceras'', within the Cyrtogomphoceratidae The Cyrtogomphoceratidae are a family in the cephalopod order Discosorida that comprises genera commonly with compressed, endogastrically curved shells. Siphuncles lie close to the ventral side, segments are broadly inflated, connecti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyrtogomphoceratidae
The Cyrtogomphoceratidae are a family in the cephalopod order Discosorida that comprises genera commonly with compressed, endogastrically curved shells. Siphuncles lie close to the ventral side, segments are broadly inflated, connecting rings thick and apically expanded thick bullettes. Chambers are short, separated by shallow, dish shaped septa. Apertures are generally simple. The Cyrtogomphoceratidae are derived from the discosorid family Reudemannoceratidae, probably from '' Reudemannoceras'', through the ancestral genus '' Ulrichoceras'', and have a range from the Middle Ordovician to the Lower Silurian. The familyTeicher, C. 1964. Nautiloidea-Discosorida. Treatise on Invertebrate Paleontology, Part K. Teichert and Moore, eds. includes: :*'' Cyrtogomphoceras'' :*'' Kiaeroceras'' :*'' Konglungenoceras'' :*'' Landeroceras'' :*'' Parryoceras'' :*'' Strandoceras'' :*'' Ulrichoceras'' ''Ulrichoceras'' is also considered the source for the exogastric Westonoceratidae. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kiaeroceras
''Kiaeroceras'' is a slender, nearly stright shelled, cyrogomphoceratid ( Nautiloidea-Discosorida) from the Upper Ordovician of northern Europe (e.g. Norway). The cross section of the shell is compressed, height greater than width. The body chamber is slightly contracted so as to narrow toward the aperture, which in some is slightly flared. The venter, narrowly rounded. The siphuncle is close to the venter, septal necks short, connecting rings thick, bullettes prominent. ''Kiaeroceras'' is thought to be derived from ''Strandoceras ''Strandoceras'' is a strongly curved cyrtogomphoceratid with a laterally compressed cross section from the middle and upper Ordovician of Northern Europe; Estonia, Norway, the U.K. The body chamber of ''Stradoceras'' is straighter and more sle ...'' although derivation is possibly from '' Cyrtogomphoceras'', which is intermediary in form. References *Flower, Rousseau H. and Curt Teichert, 1957; The Cephalopod Order Discosorida, in University of K ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyrtogomphoceras
''Cyrtogomphoceras'' is a genus of nautiloid cephalopods, recognized by its large breviconic shell with a notable endogastric curvature. The shell is fusiform in profile, reaching maximum width at or near the base of body chamber, which narrows toward the aperture. The siphuncle is large and slightly removed from the ventral side, that with the concave longitudinal profile. Siphuncle segments are short, as are chambers; septal necks recurved, connecting rings thick, bullettes at the apical end of the rings swollen. Cameral deposits are lacking. ''Cyrtogomphoceras'' seems to be derived from ''Strandoceras'' by a reduction in the degree of endogastric curvature and may have given rise to '' Landeroceras'' by a further evolutionary straightening of the shell. ''Cyrtogomphoceras'', named by Foeste, 1924, has been found in middle and upper Ordovician beds in North America and Greenland. Fossils identified as such have also been found in the Silurian of Estonia. The type species is ... [...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] |
Northern Europe
The northern region of Europe has several definitions. A restrictive definition may describe Northern Europe as being roughly north of the southern coast of the Baltic Sea, which is about 54th parallel north, 54°N, or may be based on other geographical factors such as climate and ecology. Climate The climate is mainly Oceanic climate (Cfb), Humid continental climate (Dfb), Subarctic climate (Dfc and Dsc) and Tundra (ET). Geography Northern Europe might be defined roughly to include some or all of the following areas: British Isles, Fennoscandia, the peninsula of Jutland, the Baltic region, Baltic plain that lies to the east and the many islands that lie offshore from mainland Northern Europe and the main European continent. In some cases, Greenland is also included, although it is only politically European, comprising part of the Kingdom of Denmark, and not considered to be geographically in Europe. The area is partly mountainous, including the northern volcanic islands ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phragmoceratidae
The Phragmoceratidae is a family of extinct nautiloid cephalopods from the Order Discosorida that lived during the latter part of the Silurian. Diagnosis Phragmoceratids are characterized by generally compressed, upwardly curved endogastric shells with slit-like apertures for egress and ventral siphuncles with broadly expanded segments, thick connecting rings, and small to vestigial bullettes. Phragmoceratids are morphologically similar in regards to their constricted apertures to the more cylindrical and orthoconic Mandaloceratidae, also discosorids, and to the oncocerid Hemiphragmoceratidae Hemiphragmoceratidae is a family of endogastrically brevconic oncocerids characterized by elaborately visored apertures in which the hyponomic sinus in mature specimens is on a spout-like process and there may be lateral and dorsal salients. (S ... (Sweet 1964); both which also come from the Silurian. Derivation The Phragmoceratidae are derived from the Ordovician Cyrtogomphocerat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Landeroceras
''Landeroceras'' is a genus of straight shelled cyrtogomphoceratid from the Middle Ordovician Big Horn dolomite of Wyoming. The shell of ''Landeroceras'' is a subcylindrical brevicone with the siphuncle on one side, determined as ventral. Siphuncle segments are short and well expanded into the chambers. Connecting rings are thick, septal necks cyrochoanitic to recumbent, bullettes markedly swollen. ''Landeroceras'' is at the end of a small offshoot within the discosorid family Cyrtogomphoceratidae that also includes ''Cyrtogomphoceras'', and not in the line which gave rise to the Phragmoceratidae The Phragmoceratidae is a family of extinct nautiloid cephalopods from the Order Discosorida that lived during the latter part of the Silurian. Diagnosis Phragmoceratids are characterized by generally compressed, upwardly curved endogastric sh .... References * Flower, R H and Teichert, C., 1957. The Cephalopod Order Discosorida. University of Kansas Paleontological Contributio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Discosorida
Discosorida are an order of cephalopods that lived from the beginning of the Middle Ordovician, through the Silurian, and into the Devonian. Discosorids are unique in the structure and formation of the siphuncle, the tube that runs through and connects the camerae (chambers) in cephalopods, which unlike those in other orders is zoned longitudinally along the segments rather than laterally. Siphuncle structure indicated that the Discosorida evolved directly from the Plectronoceratida rather than through the more developed Ellesmerocerida, as did the other orders. Finally and most diagnostic, discosorids developed a reinforcing, grommet-like structure in the septal opening of the siphuncle known as the bullette, formed by a thickening of the connecting ring as it draped around the folded back septal neck. Evolution The origin of the Discosorida is unknown, thought at one timeRousseau H. Flower. 1964. The Nautiloid Order Ellesmerocerida (Cephalopods); relevant pages. Memoir 12, Ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prehistoric Nautiloid 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. T ... [...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] |
