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Otoitidae
Otoidtidae: stephanoceratoid ammonitina from the early Middle Jurassic that begin as cadicones but become more planualte with age; derived from the Hammitoceratidae (Hildoceratoidea), probably through '' Erycites'' by way of ''Abbasites''. Shells begin barrel shaped with depressed whorls, broad outer rims, and deep, crater-like umbilici—cadiconic—but become compressed, with the out rims becoming bluntly rounded—planulate. Ribbing is common; may be heavy and tuberculate on the umbilical shoulders and may divide along the flanks before crossing the outer rim -the venter- uninterrupted. The Otoitidae is the ancestral family of the Stephanoceratoidea and is known only from a relatively short interval of time within the Bajocian stage at the beginning the Middle Jurassic and begins with ''Docidoceras''. They gave rise, probably through varieties of ''Docidoceras'' to the Stephanoceratidae Stephanoceratidae is a family of planulate and coronate ammonites within the Stepha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Otoites
''Otoites'' is the type genus of the Ammonitida, ammonite family Otoitidae that live during the Middle Jurassic.Arkell ''et al'', 1957; Treatise on Invertebrate Paleontology, Part L, Ammonoidea; Geological Society of America and Univsity of Kansas press. part L (L232,L287) The Otoitidae, which is part of the superfamily Stephanoceratoidea, are part of the well known subclass of prehistoric cephalopods known in general terms as ammonites ''Otoites'' is characterized by barrel-shaped, cadiconic, inner whorls and contracted last whorl; coarse ribs with long secondaries that come off of low lateral tubercles; and lappets flanking the aperture. Distribution The Jurassic of Spain References Jurassic ammonites Fossils of Spain Bajocian life Ammonitida genera Stephanoceratoidea {{ammonitina-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stephanoceratoidea
Stephanoceratoidea, formerly Stephanocerataceae, is a superfamily of middle- upper Jurassic ammonoid cephalopods within the order Ammonitida containing diverse forms, generally with sharp ribbing and complex suture lines. Aptychi are believed to be mostly granular (Granulaptycus) or concentrically ribbed on the surface (Praestriaptychus) (Arkell ''et al.'' 1957) Morphologic variation The shells of the Stephanoceratoidea, which determine the different included families, are highly variable in form. They are discoidal and evolute with all whorls exposed, spheroidal and involute with only the outer whorl showing, cadiconic with a deep umbilicus and broad ventral margin, and oxiconic with the ventral margin sharp. They are united by being generally sharply ribbed and by their complex suture lines with a dominant 1st lateral lobe and a well-developed umbilical lobe. (Arkell ''et al.'' 1957) Taxonomy Stephanoceratoidea contains five families according to Donovan ''et al.'' (1981), a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abbasites
''Abbasites'' is an extinct genus of ammonites from the early Middle Jurassic epoch, included in the ammonitid family Erycitidae. Description ''Abbasites'' is small and subglobular with ribbing that divides high on its sides and which has an interruption on the venter that replaces the keel, generally characteristic of the Hammatoceratidae Arkell,Kummel, and Wright 1957. Mesozoic Ammonoidea, Treatise on Invertebrate Paleontology, Part L, Mollusca 4 Classification ''Abbasites'' was originally described by Sydney S. Buckman in 1921, with ''A. abbas'' as its type species, and was considered by some to be a subgenus of '' Erycites''. ''Abbasites'' was included in the Otoitidae, the ancestral family of the Stephanoceratoidea, according to Westermann (1965)Imlay, Ralph W . 1984. Early and Middle Bajocian (Middle Jurassic) Ammonites from Southern Alaska; U.S.G.S PP 132/ref>Westernamm,G. E. G. 1965.Septal and Sutural Patterns in Evolution and Taxonomy of Thamboceratidae and Clydonicera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Docidoceras
''Docidoceras'' is an extinct ammonite genus from the order Ammonitida that lived during the Middle Jurassic. ''Docidoceras'' is included in the family Otoitidae which makes up part of the ammonite superfamily Stephanoceratoidea. ''Docidoceras'' has a broad, finely ribbed, evolute shell with a depressed whorl section. The venter, the outer rim, is broadly arched and crossed by the ribs without interruption. The dorsum, on the inner rim of the whorls is broadly impressed. Distribution Fossils of ''Docidoceras'' have been found in: * Laberge Group, Yukon, Canada * Agoudim Formation, Morocco * Andalusia, Spain * Inferior Oolite The Inferior Oolite is a sequence of Jurassic age sedimentary rocks in Europe. It was deposited during the Middle Jurassic.Weishampel, David B; et al. (2004). "Dinosaur distribution (Middle Jurassic, Europe)." In: Weishampel, David B.; Dodson, Pet ..., United Kingdom * Kialagvik Formation, Alaska, United States References Bibliography * Arkell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emileia
''Emileia'' is an extinct genus from a well-known class of fossil cephalopods, the ammonites, that lived during the early part of the Bajocian. ''Emileia''is a large form with fine ribbing that includes may secondaries. It begins as a barrel shaped cadicone, with an eccentric, more or less smooth body chamber.Mesozoic Ammonoidea, Treatise on Invertebrate Paleontology part L (L232,L287) ''Emileia'' is included in the family Otoitidae Otoidtidae: stephanoceratoid ammonitina from the early Middle Jurassic that begin as cadicones but become more planualte with age; derived from the Hammitoceratidae (Hildoceratoidea), probably through '' Erycites'' by way of ''Abbasites''. Sh ... and superfamily Stephanoceratoidea of the Ammonitina References Jurassic ammonites Ammonites of Europe Bajocian life Ammonitida genera Stephanoceratoidea {{ammonitina-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stephanoceratidae
Stephanoceratidae is a family of planulate and coronate ammonites within the Stephanoceratoidea.Arkell, Kummel, and Wright, 1957. Mesozoic Ammonoidea; Treatise on Invertebrate Paleontology, Part L, Mollusca 4. Shells are evolute so that all whorls are exposed and have strong ribbing that bifurcates, that is splits in two, on the flanks. Many have tubercles at the point of bifurcation. Whorl sections are generally subequant; the outer rim, or venter, commonly rounded. Stephanoceratidae is derived from the Otoitidae. Their fossils are found in upper Middle- and lower Upper Jurassic sediments. Subfamilies and genera * Cadomitinae * Frebolditinae * Garantianinae * Mollistephaninae * Stephanoceratinae *''Ermoceras'' *''Kosmermoceras'' *''Kumatostephanus'' *''Skirroceras ''Skirroceras'' is a Stephanoceratacean (ammonite) genus belonging to the family Stephanoceratidae. These fast-swimming carnivores lived during the Jurassic The Jurassic ( ) is a Geological period, geologic peri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammonitina
Ammonitina comprises a diverse suborder of ammonite cephalopods that lived during the Jurassic and Cretaceous periods of the Mesozoic Era. They are excellent index fossils, and it is often possible to link the rock layer in which they are found to specific geological time periods. The shells of Ammonitina are typically planospiral; coiled in a plane, symmetrical side to side. Shells vary in form, including those that are evolute, such that all whorls are exposed, and those that are strongly involute with only the outer whorl showing. They may be strongly ribbed, some bearing nodes and spines; others are entirely smooth. Some have broad rounded venters (the outer rim); in others the venter is sharp and keel-like. Sutures are generally ammonitic, with intricately patterned saddle and lobes. However, in some derived forms the suture becomes simplified, ceratitic, even goniatitic. The Ammonitina are derived from the Phylloceratina, another ammonitid suborder which has its origin in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations containing land animal fossils include the Forest Marble Formation in England, the Kilmaluag Formation in Scotland,British Geological Survey. 2011Stratigraphic framework for the Middle Jurassic strata of Great Britain and the adjoining continental shelf: research report RR/11/06 British Geological Survey, Keyworth, Nottingham. the Daohugou Beds in China, the Itat Formation in Russia, and the Isalo III Formation of western Madagascar. Paleogeography During the Middle Jurassic Epoch, Pangaea began to separate into Laurasia and Gondwana, and the Atlantic Ocean formed. Eastern Laurasia was tectonically active as the Cimmerian plate continued to collide with Laurasia's southern coast, completely closing the Paleo-Tethys Ocean. A subd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bajocian
In the geologic timescale The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geoch ..., the Bajocian is an age (geology), age and stage (stratigraphy), stage in the Middle Jurassic. It lasted from approximately 170.3 annum, Ma to around 168.3 Ma (million years ago). The Bajocian Age succeeds the Aalenian Age and precedes the Bathonian Age. Stratigraphic definitions The Bajocian Stage takes its name from the Latin name (Bajocae) of the town of Bayeux, in the region of Normandy in France. The stage was named and introduced in scientific literature by French palaeontologist Alcide d'Orbigny in 1842. The base of the Bajocian stage is defined as the place in the stratigraphic column where fossils of the ammonite genus ''Hyperlioceras'' first appear. A global reference profile (a GSSP) for the ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
