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Diestoceratidae
Diestoceratidae is a family in the nautiloid cephalopod order Oncocerida The Oncocerida comprise a diverse group of generally small nautiloid cephalopods known from the Middle Ordovician to the Mississippian (early Carboniferous; one possible member is known from the Early Permian), in which the connecting rings are t ... with compressed, straight to faintly endogastic breviconic shells with a marginal siphuncle that contains discrete, irregular actinosphonate deposits. The Diestoceratidae contains five known genera. They are: *'' Diestoceras'' *'' Danoceras'' *'' Dowlingoceras'' *'' Lyckholmoceras'' *'' Suttonoceras'' References External linksDiestoceratidae -Paleobio db* Sweet, Walter C. 1964. Nautiloidea -Oncocera. Treatise on Invertebrate Paleontology, Part K. Geological Soc. of America & Univ Kansas Press. {{Taxonbar, from=Q5275040 Oncocerida Prehistoric nautiloid families ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oncocerida
The Oncocerida comprise a diverse group of generally small nautiloid cephalopods known from the Middle Ordovician to the Mississippian (early Carboniferous; one possible member is known from the Early Permian), in which the connecting rings are thin and siphuncle segments are variably expanded (Flower, 1950). At present the order consists of some 16 families, a few of which, such as the Oncoceratidae, Brevicoceratidae, and Acleistoceratidae contain a fair number of genera each while others like the Trimeroceratidae and Archiacoceratidae are represented by only two or three (Sweet, 1964). Physical characteristics The shells of oncocerids are primarily somewhat compressed cyrtoconic brevicones. More advanced forms include gyrocones, serpenticones, torticones, and elongate orthocones and cyrtocones, reflective of the different families and genera (Flower, 1950; Sweet, 1964). The siphuncle in the Oncocerida is commonly located at or near the ventral margin. Connecting rings are mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Danoceras
''Danoceras'' is an essentially straight shelled oncocerid named by Troedsson in 1926, and included in the Diestoceratidae Diestoceratidae is a family in the nautiloid cephalopod order Oncocerida The Oncocerida comprise a diverse group of generally small nautiloid cephalopods known from the Middle Ordovician to the Mississippian (early Carboniferous; one possible .... It has been found in the upper, and possibly middle, Ordovician of Europe, (Estonia), Greenland, and Russia, (Taimyr Peninsula). Named species include ''Danoceras ravni'', type, ''D. inutile'', ''D. scandinavicum'', and ''D. skalbergensis''. The ''Danoceras'' shell is oval in section, laterally compressed with broadly rounded sides and narrowly rounded dorsum and venter. Chambers are short, septa close spaced, sutures straight and transverse. The siphuncle is subventral, close to but not touching the ventral margin. In form, cyrtochoanitic, necks recumbant. Related genera include '' Diestoceras'', '' Dowlingo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nautiloidea
Nautiloids are a group of marine cephalopods (Mollusca) which originated in the Late Cambrian and are represented today by the living ''Nautilus'' and ''Allonautilus''. Fossil nautiloids are diverse and speciose, with over 2,500 recorded species. They flourished during the early Paleozoic era, when they constituted the main predatory animals. Early in their evolution, nautiloids developed an extraordinary diversity of shell shapes, including coiled morphologies and giant straight-shelled forms ( orthocones). Only a handful of rare coiled species, the nautiluses, survive to the present day. In a broad sense, "nautiloid" refers to a major cephalopod subclass or collection of subclasses (Nautiloidea ''sensu lato''). Nautiloids are typically considered one of three main groups of cephalopods, along with the extinct ammonoids (ammonites) and living coleoids (such as squid, octopus, and kin). While ammonoids and coleoids are monophyletic clades with exclusive ancestor-descendant rela ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
