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Plectoceratidae
The Plectoceratidae is a family of tarphycerids in the suborder Barrandeocerina established as a place for the genus '' Plectoceras''; defined (Sweet 1964) simply as coiled, costate barrandeocerids with subcentral adult siphuncle. According to Sweet, in the original ''Treatise'' Part K, the Plectoceratidae included only ''Plectoceras''. Flower, 1984, however added six other genera, two new and four removed from both the Barrandeoceratidae and Apsidoceratidae. Genera according to Flower, 1984 are: '' Plectoceras'' Hyatt -type genus '' Avilionella'' -removed from Barradeoceratidae '' Bodeiceras'', Flower 1984. added '' Chidleyenoceras'' - removed from the Apsidoceratidae '' Metaplectoceras'', Flower (?synonym for Plectoceras) '' Laureloceras'' Flower 1957, removed from Barrandeoceratidae '' Laurelplecoceras'' Flower 1984 -added According to Flower, 1984, ''Plectoceras'', and therefore the Plectoceratidae, is derived from the Tarphyceratid genus '' Campbelloceras'' while ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Avilionella
''Avilionella'' is a Middle Ordovician tarphyceroid genus consisting of closely coiled, compressed shells with a small perforation in the center, shallow dorsal impression, and subventral tubular siphuncle with thin connecting rings. Chambers are very short, separated by closely spaced, dish-shaped septa. Coiling becomes loose in the mature, adoral, part of the shell. The subventral, tubular siphuncle along with the looser coiling in the mature portion of the shell and perforation at the center put ''Avilionella'' in the Plectoceratidae The Plectoceratidae is a family of tarphycerids in the suborder Barrandeocerina established as a place for the genus '' Plectoceras''; defined (Sweet 1964) simply as coiled, costate barrandeocerids with subcentral adult siphuncle. According to ... (Flower, 1984) rather than in the Barrandeoceratidae (Sweet 1964) where it had been placed earlier. It has been found the New York and Ontario. References *Rousseau H. Flower, 1984. ''Bodeicera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chidleyenoceras
''Chidleyenoceras'' is a Middle Ordovician tarphyceroid with a closely coiled, evolute shell; whorl section subquadrate, widest just above a broadly rounded venter; dorsum with a broad shallow impression; sutures moderately spaced, weakly sinuous; siphuncle large, subventral, apparently orthochoantitic with tubular segments. The tubular, subventral siphuncle separates ''Chidleyenoceras'' from the Apsidoceratidae (Sweet, 1964) where it had been included and puts it well into the Plectoceratidae (Flower, 1984). References * Flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ..., (1984). ''Bodeiceras''; a New Mohawkian Oxycone, with Revision of the Older Barrandeocerida and Discussion of the Status of the Order. Journal of Paleontology v. 58, no.6, pp 1372–1379, Nov. 1984. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laureloceras
''Laureloceras'' is a genus of the tarphycerid family Plectoceratidae that lived during the Middle Silurian in what is now North America. The shell of ''Laureloceras'' is a smooth, slender, compressed cyrtocone or gyrocone with the venter more narrowly rounded than the dorsum. Sutures are transverse but may form broad lateral lobes. The siphuncle is subventral - close to the outer rim; necks are straight, connecting rings slightly expanded into the chambers. Cameral and siphonal deposits are lacking. ''Laureloceras'' was previously included in the Barrandeoceratidae (Flower, 1950, Sweet, 1964) but was removed (Flower, 1984) primarily on the bases of the subventral siphuncle (Barrandeoceratid siphuncles are central - subcentral. Reassignment to the Tarphycerida from the Barrandeocerida is based on barrandeoceratid taxa being polyphyletic (having more than one common ancestor). Barrandeocerina The Barrandeocerina comprise a suborder of Early Paleozoic nautiloid cephalopods, pri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tarphycerida
The Tarphycerida were the first of the coiled cephalopods, found in marine sediments from the Lower Ordovician (middle and upper Canad) to the Middle Devonian. Some, such as '' Aphetoceras'' and '' Estonioceras'', are loosely coiled and gyroconic; others, such as '' Campbelloceras'', '' Tarphyceras'', and '' Trocholites'', are tightly coiled, but evolute with all whorls showing. The body chamber of tarphycerids is typically long and tubular,Furnish and Glenister 1964; Nautiloidea - Tarphycerida; In the ''Treatise on Invertebrate Paleontology'' Vol K; Teichert and Moore, (eds) GSA and U of Kansas Press 1964 as much as half the length of the containing whorl in most, greater than in the Silurian Ophidioceratidae. The Tarphycerida evolved from the elongated, compressed, exogastric Bassleroceratidae, probably ''Bassleroceras'', around the end of the Gasconadian through forms like ''Aphetoceras''. Close coiling developed rather quickly, and both gyroconic and evolute forms are fou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barrandeocerina
The Barrandeocerina comprise a suborder of Early Paleozoic nautiloid cephalopods, primitively coiled but later forms may be cyrtoconic, gyroconic, torticonic, and even breviconic, all having empty siphuncles with thin connecting rings. The Barrandeocerina were originally defined as a separate order by Rousseau Flower (Flower and Kummel, 1950), but since then have been united within the Tarphycerida as a suborder (Teichert 1988). Derivation is from the Tarphyceratidae. In early forms the siphuncle is central or subcentral, orthochoanitic (septal necks short and straight), and thin, with tubular segments. Later forms include those with cyrtochoanitic septal necks (curved outward) and segments that may be slightly to strongly expanded into the chambers. Taxonomy Six families are included in the Barrandeocerina, (ex Barrandeocerida). : Barrandeoceratidae M Ord-M Dev :Plectoceratidae M-U Ord :Apsidoceratidae M-U Ord : Uranoceratidae U Ord-M Sil : Lechritrochoceratidae M-U Si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Campbelloceras
''Campbelloceras'' is a tarphyceratid nautiloid known from the Lower Ordovician, Upper Canadian Epoch of North America, where it is widespread. ''Campbelloceras'' was named by Ulrich and Foerste in 1936. The shell of ''Campbelloceras'' has a circular whorl section, only slightly impressed, and a siphuncle that is close to the venter in all growth stages. ''Campbelloceras'' differs from ''Tarphyceras'' in that the rate of expansion is greater, the siphuncle is proportionally largers, and an impression is shallower. ''Campbelloceras'' may have given rise to the barrandeocerid '' Plectoceras'' (Plectoceratidae) through simplification of the connecting rings, and to ''Tarphyceras'' through tighter coiling, development of a deeper impression, and reduction in the size of the siphuncle. ''Campbelloceras'' may be conceivably derived from '' Estonioceras'' (Estonioceratidae). The cross section of ''Campbelloceras'' and that of the outer whorl of ''Estonioceras'' are similar, except f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barrandeoceratidae
The Barrandeoceratidae is a family of coiled nautiloids included in the Tarphycerida (''sensu lato'') that lived from the Middle Ordovician to the Middle Devonian, characterised by mostly compressed shells with a subcentral siphuncle composed of thin-walled segments that may become secondarily ventral.(Flower and Kummel 1950, Sweet 1964). The Barrandeoceratidae are derived from the tarphyceratid genus, ''Centrotarphyceras'' through '' Barrandeoceras'' (Flower 1984), and is the source for the Uranoceratidae and Nephriticeratidae. These three families form the barrandeoceratid group. Sometimes a fourth family, the Bickmoritidae, is added, based on the genus ''Bickmorites''. Genera (Flower 1984) include '' Barrandeoceras'', '' Centrocyrtoceras'', '' Paquettoceras'', '' Savageoceras'', '' Gasconsoceras'', ''Haydenoceras'', and '' Paraplectoceras''; and if included, '' Bickmorites''. ''Avilionella'' and ''Laureloceras'', included in the Barrandeocerida in the ''Treatise on Invert ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apsidoceratidae
The Apsidoceratidae is a family of Middle and Upper Ordovician Barrandeocerina, (a suborder of tarphycerids), characterized by curved or coiled, smooth, transversely marked, or laterally costate shells, with a conspicuous hyponomic sinus. Early whorl sections tend to be subtriangular; become broader and dorsally impressed in closely coiled forms. Sutures are with lateral lobes in primitive forms but are without lateral lobes, but with ventral lobes in more advanced species with broader sections. Siphuncles are between the center and ventral margin, but not close to either. Genera remaining in the Apsidoceratidae include: :'' Apsidoceras'' :'' Charactoceras'' :'' Charactocerina'' :'' Deckeroceras'' :'' Fremontoceras'' :'' Wilsonoceras'' '' Chidleyenoceras'', previously assigned, tentatively, to the Apsidoceratidae has been reassigned (Flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barrandeoceras
''Barrandeoceras'' is a large, coiled, Middle Ordovician nautiloid cephalopod and part of the Tarphycerida. The shell is serpenticonic with whorls touching but not embracing. The adult body chamber becomes freed of the preceding whorl, a rather common character among tarphycerids. Whorl section is oval, somewhat more narrowly rounded ventrally, on the outer rim, than dorsally, on the inner rim. Prominent lateral ribs, at least on inner whorls. Grow lines show a distinct hyponomic sinus. Sutures have lateral lobes. The siphuncle is subcentral. Barrandeoceras has been found in the Middle Ordovician of New York, Ontario, and Quebec. It is the type genus for the Barrandeoceratidae The Barrandeoceratidae is a family of coiled nautiloids included in the Tarphycerida (''sensu lato'') that lived from the Middle Ordovician to the Middle Devonian, characterised by mostly compressed shells with a subcentral siphuncle composed of .... References *Rousseau H Flower and Bernhard Kümmel ... [...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] |
