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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] |
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] |
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] |
Elrodoceras
''Elrodoceras'' is a genus of armenoceratids, (Cephalopoda, Actinocerida), that grew fairly large, characterized by a straight shell, slightly curved at the apex, a siphuncle narrower than that of ''Armenoceras'' but with segments still wider than long, and an arched endosiphuncular canal system. ''Elrodoceras'', which comes from the Middle Silurian of North America and Europe, is a late armenoceratid and, according to Curt Teichert, 1964, a member of one of the two branches 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 ... that also includes ''Armenoceras'' and '' Monocyrtoceras''. References * Curt Teichert, 1964. Actinoceratoidea, Treatise on Invertebrate Paleontology, Part K. Geological Society of America and University of Kansas press. Prehistori ... [...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] |
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] |
Monocyrtoceras
''Monocyrtoceras'' is a genus of armenoceratids (Cephalopoda) from the Middle Silurian of North America (Wisconsin), with a gently curved shell and a siphuncle like that of ''Elrodoceras''. According to Teichert, 1964, in the Treatise part K, ''Monocyrtoceras'' along with ''Elrodoceras'' and ''Armenoceras'' forms one of the two branches 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 .... 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] |
Paleozoic Life Of The Northwest Territories
The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ''zōḗ'' (), "life", meaning "ancient life" ). It is the longest of the Phanerozoic eras, lasting from , and is subdivided into six geologic periods (from oldest to youngest): # Cambrian # Ordovician # Silurian # Devonian # Carboniferous # Permian The Paleozoic comes after the Neoproterozoic Era of the Proterozoic Eon and is followed by the Mesozoic Era. The Paleozoic was a time of dramatic geological, climatic, and evolutionary change. The Cambrian witnessed the most rapid and widespread diversification of life in Earth's history, known as the Cambrian explosion, in which most modern phyla first appeared. Arthropods, molluscs, fish, amphibians, reptiles, and synapsids all evolved during the Paleozoic. Life began in the ocean but even ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleozoic Life Of Manitoba
The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ''zōḗ'' (), "life", meaning "ancient life" ). It is the longest of the Phanerozoic eras, lasting from , and is subdivided into six geologic periods (from oldest to youngest): # Cambrian # Ordovician # Silurian # Devonian # Carboniferous # Permian The Paleozoic comes after the Neoproterozoic Era of the Proterozoic Eon and is followed by the Mesozoic Era. The Paleozoic was a time of dramatic geological, climatic, and evolutionary change. The Cambrian witnessed the most rapid and widespread diversification of life in Earth's history, known as the Cambrian explosion, in which most modern phyla first appeared. Arthropods, molluscs, fish, amphibians, reptiles, and synapsids all evolved during the Paleozoic. Life began in the ocean but eve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ordovician Cephalopods Of North America
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 Cambri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silurian Extinctions
The Silurian ( ) is a period (geology), geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago (annum, Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozoic Era (geology), Era. As with other geologic periods, the Rock (geology), rock beds that define the period's start and end are well identified, but the exact dates are uncertain by a few million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when up to 60% of marine genera were wiped out. One important event in this period was the initial establishment of terrestrial life in what is known as the Silurian-Devonian Terrestrial Revolution: vascular plants emerged from more primitive land plants, dikaryan fungi started expanding and diversifying along with glomeromycotan fungi, and three groups of arthropods (myriapods, arachnids and Hexapoda, hexapods) became fully 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] |
Silurian Animals Of Asia
The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago (Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozoic Era. As with other geologic periods, the rock beds that define the period's start and end are well identified, but the exact dates are uncertain by a few million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when up to 60% of marine genera were wiped out. One important event in this period was the initial establishment of terrestrial life in what is known as the Silurian-Devonian Terrestrial Revolution: vascular plants emerged from more primitive land plants, dikaryan fungi started expanding and diversifying along with glomeromycotan fungi, and three groups of arthropods ( myriapods, arachnids and hexapods) became fully terrestrialized. A significant evolutionary milestone during ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
