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Bathmoceras
''Bathmoceras'' is a primitive cephalopod genus from the Middle and Upper Ordovician. It is a member of the order Cyrtocerinida and is the only genus in the family Bathmoceratidae. Derivation At one time ''Bathmoceras'' was thought to have possibly given rise to ''Polydesmia'', once thought to have been the ancestral actinocerid. Since then revision of actinocerid phylogeny and of Ordovician stratigraphy in east Asia have cast doubts on this hypothesis. ''Bathmoceras'' is most likely derived from ''Eothinoceras'' through lengthening of the septal necks and of the inward projections of the connecting rings in a forward direction. ''Eothinoceras'' differs in that the septal necks are vestigial rather than being somewhat long as in ''Bathmoceras'' and that the inward projections of the connecting rings point straight in rather than projecting forward. Both are straight shelled or slightly exogastric. Eothinoceras is also apparently more slender. Furnish and Glenister also include ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bathmoceratidae
''Bathmoceras'' is a primitive cephalopod genus from the Middle and Upper Ordovician. It is a member of the order Cyrtocerinida and is the only genus in the family Bathmoceratidae. Derivation At one time ''Bathmoceras'' was thought to have possibly given rise to ''Polydesmia'', once thought to have been the ancestral actinocerid. Since then revision of actinocerid phylogeny and of Ordovician stratigraphy in east Asia have cast doubts on this hypothesis. ''Bathmoceras'' is most likely derived from ''Eothinoceras'' through lengthening of the septal necks and of the inward projections of the connecting rings in a forward direction. ''Eothinoceras'' differs in that the septal necks are vestigial rather than being somewhat long as in ''Bathmoceras'' and that the inward projections of the connecting rings point straight in rather than projecting forward. Both are straight shelled or slightly exogastric. Eothinoceras is also apparently more slender. Furnish and Glenister also include ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyrtocerinida
Cyrtocerinida is an order of Ordovician nautiloid cephalopods. The order includes the families Cyrtocerinidae and Eothinoceratidae, as well as the genera '' Bathmoceras'' and '' Rummoceras''. Cyrtocerinids can be characterized by a broad siphuncle encased by very thick connecting rings with concave outer surfaces. Despite their thickness, the connecting rings are nautilosiphonate, meaning that their inner layer is a poorly-mineralized organic sheath (similar to modern nautiluses) rather than a porous calcified structure. There are various calcified endosiphuncular deposits such as collars and longitudinal ridges on the inner layer of the connecting ring. These deposits are discontinuous, reforming after each chamber. This differentiates them from the continuous endosiphuncular ridges found in other nautiloids, such as the related oncocerids. The overall shell shape is typically orthoconic (straight, pointed) or breviconic (stout). The body chamber is oncomyarian, meaning ... [...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] |
Treatise On Invertebrate Paleontology
The ''Treatise on Invertebrate Paleontology'' (or ''TIP'') published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and covering every phylum, class, order, family, and genus of fossil and extant (still living) invertebrate animals. The prehistoric invertebrates are described as to their taxonomy, morphology, paleoecology, stratigraphic and paleogeographic range. However, taxa with no fossil record whatsoever have just a very brief listing. Publication of the decades-long ''Treatise on Invertebrate Paleontology'' is a work-in-progress; and therefore it is not yet complete: For example, there is no volume yet published regarding the post-Paleozoic era caenogastropods (a molluscan group including the whelk and Common periwinkle, periwinkle). Furthermore, every so often, previously published volumes of the ''Treatise'' are revised. Evolution of the proje ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macdonnell Ranges
The MacDonnell Ranges, or Tjoritja in Arrernte, is a mountain range located in southern Northern Territory. MacDonnell Ranges is also the name given to an interim Australian bioregion broadly encompassing the mountain range, with an area of .IBRA Version 6.1 data The range is a long series of mountains in central , consisting of parallel ridges running to the east and west of . The mountain range contains many spectacular gaps and gorges as well as areas of A ... [...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] |
Ellesmerocerida
The Ellesmerocerida is an order of primitive cephalopods belonging to the subclass Nautiloidea with a widespread distribution that lived during the Late Cambrian and Ordovician. Morphology The Ellesmerocerida are characterized by shells that are typically small, some even tiny, with close-spaced septa and relatively large ventral siphuncles. In some genera (e.g. '' Paleoceras''), the septa are uniformly spaced. Shells of ellesmerocerids are typically smooth and compressed and vary in form. They may be breviconic (short) or longiconic (elongate), straight (orthoconic) or curved (cyrtoconic). Cyrtoconic forms are usually endogastric, with longitudinally convex ventral margins. The apeces of straight forms typically have an endogastric curvature. Some may have grown to as much as 15 cm. Siphuncle segments are tubular or concave. Septal necks are short. Connecting rings which may appear layered are thick and typically wedge shaped with their maximum width at or near where ... [...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] |
Ordovician Cephalopods Of Europe
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 Cambrian Perio ... [...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] |
