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Actinoceratidae
The Actinoceriatidae are a family of actinocerids named by Saemann in 1853 for those that grew to have large shells with blunt apices and large siphuncles with widely expanded segments and a generally arcuate endosiphucular canal system.Teichert 1964. Actinoceratoidea, Treatise on Invertebrate Paleontology, part K.(Nautiloidea) Their range is from the upper Middle Ordovician to the Lower Silurian. 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 Actinoceratids are derived from ''Wutinoceras'', possibly through an early '' Armenoceras'' or through '' Nybyoceras''Flower 1957.Studies of the Actinoceratida; Memoir 2; New Mexico Bureau of Mines and Mineral Resources, Socorro, NM and give rise to ''Lambeoceras'' and to the Huroniidae. Seven genera are included in the Actinoceratidae, ''Actinoceras'', '' Flowerocer ... [...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] |
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] |
Kochoceras
''Kochoceras'' is an extinct nautiloid genus from the later Ordovician belonging to the family Actinoceratidae and found in North America. Morphology ''Kochoceras'' is relatively short, breviconic, and grew to be fairly large with a shell more rapidly expanding than in ''Actinoceras''. The ventral, or under, side is strongly flattened with prominent lobes that may give the impression of ''Lambeoceras''. However septa in ''Kochoceras'' are more widely spaced and the siphuncle, which is proportionally very large, is in broad contact with the ventral wall. The siphucle in ''Lambeoceras'' is proportionally much smaller and is removed about one diameter from the ventral wall. The diameter of the siphuncle in the apical part of ''Kochoceras'' is 3/4 or more that of the shell. The siphuncle of ''Kochoceras'' is similar to that of ''Actinoceras'', the main difference between the two being that ''Kochoceras'' is breviconic (short) and has a narrow stratigraphic range, while ''Actinocera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Troostoceras
''Troostoceras'' is a genus of actinoceratid nautiloids with a cyrtoconic shell, otherwise similar to ''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 U ...''. The shell is slightly endogastric, curved such that the under or ventral side is longitudinally concave, tucked in. The siphuncle is ventral and is in contact with the shell wall. Segments begin small but expand during growth. ''Troostoceras'' has been found in the Middle Ordovician of eastern North America and Siberia and may be a variety of ''Actinoceras'', along with '' Saffordoceras'' and '' Leurorthoceras''. References * 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 * Actinocerida Prehistoric nautiloid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saffordoceras
''Saffordoceras'' is an actinoceratid from the Middle Ordovician, found in eastern North America, characterized by a flattened venter; sutures with broad, deep ventral lobes and narrow lateral saddles; and subventral siphuncle with segments decreasing from about 0.3 to less than 0.2 the shell diameter. ''Saffordoceras'' is probably derived from ''Actinoceras''. Related contemporary genera include '' Paractinoceras'' and ''Troostoceras ''Troostoceras'' is a genus of actinoceratid nautiloids with a cyrtoconic shell, otherwise similar to ''Actinoceras ''Actinoceras'' is the principal and root genus of the Actinoceratidae, a major family in the Actinocerida, that lived during ...'' References * Curt Teichert, 1964. Actinoceratoidea. Treatise on Invertebrate Paleontology, Part K. Geological Soc of America and Univ of Kansas Press. {{Taxonbar, from=Q7398716 Actinocerida Ordovician cephalopods of North America Prehistoric nautiloid genera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paractinoceras
''Paractinoceras'' is a genus of long straight slender actinocerid nautiloid with siphuncular segments in the early stages like those of ''Actinoceras'', becoming narrower in the later stages of the chambered phragmocone like those in '' Ormoceras''. As with ''Kochoceras'' and '' Floweroceras'' ''Paractinoceras'' is considered a separate genus within the Actinoceratidae, distinct from ''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 U ...''. References * 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 * Actinocerida Prehistoric nautiloid genera Paleozoic life of Manitoba Paleozoic life of the Northwest Territories Paleozoic life of Nunavut {{paleo-nautiloide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leurorthoceras
''Leurorthoceras'' is a genus of flattened actinoceratids with a siphuncle narrower than in ''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 U ...'', segments of which tend to become longer in the mature parts of the phragmocone, the chambered part of the shell. This fossil is known from the Middle Ordovician of North America, Europe, and Siberia.Curt Teichert, 1964. Actinoceratoidea, Treatise on Invertebrate Paleontology, Part K. Geological Society of America and University of Kansas Press. References Prehistoric nautiloid genera Paleozoic life of Nunavut Ordovician cephalopods of North America Ordovician cephalopods of Europe {{paleo-nautiloidea-stub ... [...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] |
Silurian Cephalopods
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 durin ... [...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] |
Prehistoric Nautiloid Families
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] |
Ormoceras
''Ormoceras'' is an actinocerid nautiloid genus and type for the family Ormoceratidae, found in North America from the late Chazyan through the early Cincinnatian of the Middle and Upper Ordovician, but which continued through the Devonian worldwide. ''Ormoceras'' is a characterized by its straight shell, more or less circular in cross section, and a relatively narrow subcentral siphuncle composed of globular segments in which the radial canals in the endosiphuncular canal system are straight and normal to the central canal. Septal necks are short, narrowly rounded or sharply recurved, but never recumbent. As with most actinocerids, cameral deposits are common. ''Ormoceras'' is derived from ''Adamsoceras'' which has a siphuncle with the same general form but in which the canal system is reticulate as in ''Wutinoceras''. ''Ormoceras'' gave rise to ''Deiroceras'' early on during the Mohawkian (Middle Ordovician) and slightly later to ''Troedssonoceras''. Ormoceras also gave ris ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
