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Eoderoceratidae
Eoderoceratidae is the ancestral and most primitive family of the Eoderoceratoidea; lower Jurassic ammonite cephalopods, characterized by evolute, commonly serpenticonic, shells that had long body chambers and would have had no stable floating position; and thus resemble contemporary Psiloceratoidea. Spines, or tubercles, are typically found in two rows on the inner and outer parts of the whorl sides, joined by radial ribs. These are often more developed on the inner and middle whorls, becoming less so or absent on the outer. Sutures are highly complex. The Eoderoceratidae can be divided into two subfamilies, the Xiphoceratinae which is the earliest and in which there is an early maximum development of spines of the inner whorls, and the Eoderoceratinae. Two other subfamilies were included in the Treatise 1957 but are now regarded as families in their own right, These are the Phricodoceratidae and Coeloceratidae Genera that have been attributed to the Xiphoceratinae are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eoderoceratoidea
Eoderoceratoidea is a superfamily of true ammonites (suborder Ammonitina) from the Lower Jurassic, comprising seven phylogenetically related families, characterized in general by having ribbed evolute shells that commonly bear spines or tubercles. Adult shell size ranges from 2 or 3 cm to giants reaching 50 cm in such genera as '' Apoderoceras'', '' Epideroceras'', and ''Liparoceras''.Donovan,D.T., Callomon and Howarth 1981. Classification of the Jurassic Ammonitina; Systematics Association. Arkell ''et al.'', 1957. Mesozoic Ammonoidea, in Treatise on Invertebrate Paleontology, (Part L); Geological Soc. of America and University of Kansas press The earliest known eodoceroceratoidean is the eoderoceratid genus ''Microderoceras''. Although its origin is uncertain, it is likely that it is derived from the Psiloceratoidea. It has also been proposed, with some imagination, that ''Microderoceas'' has its origin some earlier Jurassic lytoceratid such as ''Analytoceras'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bifericeras
''Bifericeras'' is a Lower Jurassic ammonite belonging to the family Eoderoceratidae, and sometimes placed in the subfamily Xipherceratinae. Whorls are strongly depressed, but still evolute in coiling. The early growth state is prolonged, and smooth, followed by a late growth stage with rounded, straight, bituberculate ribs. ''Bifericeras'' was named by Buckman in 1913 and is found in Europe. Biostratigraphic significance The International Commission on Stratigraphy (ICS) has assigned the First Appearance Datum of ''Bifericeras donovani'' and of genus ''Apoderoceras'' the defining biological marker for the start of the Pliensbachian Stage of the Jurassic, 190.8 ± 1.0 million years ago. Distribution Only found at Dimmer Camp, Castle Cary, Somerset ( en, All The People of Somerset) , locator_map = , coordinates = , region = South West England , established_date = Ancient , established_by = , preceded_by = , origin = , lord_lieutenant_office =Lord Lieutenant of S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microderoceras
''Microderoceras'' is a flat sided, evolute, radially ribbed Lower Jurassic ammonite belonging to the ammonitid family Eoderoceratidae and superfamily Eoderoceratoidea. Its whorls are subquadrangular in section; venter on the outer rim, rounded; sides with two rows if distinct spines, tubercles on internal molds, formed at either end of the ribs. The lateral surface of the ribcage is concave toward both sides, the lateral side of the dorsal and the lateral side of the ventral surface. The ribs are divided into six pairs (1-3) of the following types: 2-3 is the only type. In the first type, the ribs on the ventral face are fused to the ribs on the ventral sides; the ribs on the dorsal face are fused to the ribs on the dorsal sides. The second type represents the ribbed body, the ribs are in the same arrangement as in the first type and the rib cage does not fuse to the dorsal surface. These shelled cephalopods, named by Alpheus Hyatt in 1871, are part of the now extinct Ammonoid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Promicroceras
''Promicroceras'' is an extinct ammonite genus from the upper Sinemurian ( Lower Jurassic) of Europe, named by Leonard Spath in 1925. ''Promicroceras'' is included in the family Eoderoceratidae, which is part of the ammonitid superfamily Eoderoceratoidea. Shells are evolute with an open umbilicus; strongly ribbed, ribs flattened on the venter, and with small spines without distinct tubercles. Distribution ''Promicroceras'' species are commonly found in South West England, particularly along the Dorset coast. Pyritic ''Promicroceras'' fossils are commonly found along the coast of Lyme Regis and Charmouth where they are well preserved in the Lower Jurassic (Sinemurian) Black Ven Marl Marl is an earthy material rich in carbonate minerals, clays, and silt. When hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae. Marl makes up the lower part o .... Fossil shops in the area commonly sell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eoderoceras
''Eoderoceras'' is an evolute, round whorled ammonite from the Lower Jurassic with an outer row of distinct spines, and in some, an inner row of tubercles, on either side; ribs only on the inner whorls. ''Eoderoceras'', named by Leonard Spath in 1925, is the type genus for the family Eoderoceratidae to which it belongs, which is part of the ammonitid superfamily Eoderoceratoidea, ammonoid cephalopods distinct from the more conservative but more successful 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. ... still around today. References *Arkell ''et al.'', 1957. Mesozoic Ammonoidea, in Treatise on Invertebrate Paleontology, (Part L); Geological Soc. of America and University of Kansas press *Donovan, Callomon and Howarth 1981 Classification of the Jurassic Ammonitin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coeloceratidae
Coeloceratidae is a family of ammonites belonging to the Eoderoceratoidea that lived during the Early Jurassic. Shells are evolute, tending to be broadly discoidal with depressed whorls bearing primary and secondary ribs that branch from outer lateral tubercles. Most of the included species have coronate inner whorls and outer tubercles only. In general, Coeloceratids resemble the Middle Jurassic ''Stephanoceras''. Once regarded as the subfamily Coeloceratinae in the Eoderoceratidae, these ammonites are now given familial rank. Genera included in the Coeloceratidae are '' Coeloceras'', ''Apoderoceras'' '' Coeloderoceras'', '' Hyperderoceras'', '' Pimalites'', '' Praesphaeroceras'', and '' Tetraspidoceras''. ''Tetraspidoceras'', which is bituberculate, is a possible ancestral member of the family. The Coeloceratidae give rise to the Dactylioceratidae The family Dactylioceratidae comprises Early Jurassic ammonite genera with ribbed and commonly tuberculate shells that res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crucilobiceras
''Crucilobiceras'' is an ammonoid cephalopod genus from the Lower Jurassic belonging to the eoderoceratoidean family Eoderoceratidae. ''Cruciliboceras'' has an evolute shell, such that all whorls are well exposed, with persistent radial ribbing and with spines or tubercles on the outer, ventral, rim, and in some, tubercles in the inner, umbilical, rim. The genus ''Crucilobiceras'' is commonly found along the Jurassic Coast of England. ''Metaderoceras'', named by Leonard Spath in 1925, is a jr. synonym for ''Crucilobiceras'' named by S.S. Buckman in 1920 according to Arkell ''et al.'', in the Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology'' (or ''TIP'') published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and co ... (1957). References ;Notes ;Bibliography *Arkell ''et al.'', 1957. Mesozoic Ammonoidea, in Treatise ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammonitida Families
Ammonitida is an order of Ammonoidea, ammonoid cephalopods that lived from the Jurassic through Paleocene time periods, commonly with intricate ammonitic sutures. Ammonitida is divided into four suborders, the Phylloceratina, Lytoceratina, Ancyloceratina, and Ammonitina. The Phylloceratina is the ancestral stock, derived from the Ceratitida near the end of the Triassic. The Phylloceratina gave rise to the Lytoceratina near the beginning of the Jurassic which in turn gave rise to the highly specialized Ancyloceratina near the end of the Jurassic. Both the Phylloceratina and Lytoceratina gave rise to various stocks combined in the Ammonitina. These four suborders are further divided into different stocks, comprising various families combined into superfamilies. Some like the Hildoceratoidea and Stephanoceratoidea are restricted to the Jurassic. Others like the Hoplitoidea and Acanthoceratoidea are known only from the Cretaceous. Still others like the Perisphinctoidea are found ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of the Mesozoic, Mesozoic Era and is named after the Jura Mountains, where limestone strata from the period were first identified. The start of the Jurassic was marked by the major Triassic–Jurassic extinction event, associated with the eruption of the Central Atlantic magmatic province, Central Atlantic Magmatic Province. The beginning of the Toarcian Stage started around 183 million years ago and is marked by an extinction event associated with widespread Anoxic event, oceanic anoxia, ocean acidification, and elevated temperatures likely caused by the eruption of the Karoo-Ferrar, Karoo-Ferrar large igneous provinces. The end of the Jurassic, however, has no clear boundary with the Cretaceous and i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sinemurian
In the geologic timescale, the Sinemurian is an age and stage in the Early or Lower Jurassic Epoch or Series. It spans the time between 199.3 ± 2 Ma and 190.8 ± 1.5 Ma (million years ago). The Sinemurian is preceded by the Hettangian and is followed by the Pliensbachian. In Europe the Sinemurian age, together with the Hettangian age, saw the deposition of the lower Lias, in Great Britain known as the Blue Lias. Stratigraphic definitions The Sinemurian Stage was defined and introduced into scientific literature by French palaeontologist Alcide d'Orbigny in 1842. It takes its name from the French town of Semur-en-Auxois, near Dijon. The calcareous soil formed from the Jurassic limestone of the region is in part responsible for the character of the classic Sancerre wines. The base of the Sinemurian Stage is at the first appearance of the ammonite genera ''Vermiceras'' and '' Metophioceras'' in the stratigraphic record. A global reference profile ( GSSP or golden spike) for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
