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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] |
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 Psiloceratoidea is a superfamily of Early Jurassic ammonoid cephalopods proposed by Hyatt in 1867, assigned to the order Ammonitida. They were ve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
Apoderoceras
''Apoderoceras'' is an extinct genus of cephalopod belonging to the ammonite subclass. Biostratigraphic significance The International Commission on Stratigraphy (ICS) has assigned the First Appearance Datum of genus ''Apoderoceras'' and of '' Bifericeras donovani'' the defining biological marker for the start of the Pliensbachian Stage of the 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 J ..., 190.8 ± 1.0 million years ago. Distribution Jurassic of Argentina, Hungary, Italy, Portugal, the United Kingdom References Eoderoceratoidea Ammonitida genera Jurassic ammonites of Europe Pliensbachian life {{Ammonitina-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Jurassic
The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-Jurassic extinction event, 201.3 Ma (million years ago), and ends at the start of the Middle Jurassic 174.1 Ma. Certain rocks of marine origin of this age in Europe are called "Lias Group, Lias" and that name was used for the period, as well, in 19th-century geology. In southern Germany rocks of this age are called Black Jurassic. Origin of the name Lias There are two possible origins for the name Lias: the first reason is it was taken by a geologist from an England, English quarryman's dialect pronunciation of the word "layers"; secondly, sloops from north Cornwall, Cornish ports such as Bude would sail across the Bristol Channel to the Vale of Glamorgan to load up with rock from coastal limestone quarries (lias limestone from S ... [...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 subduction zone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stephanoceras
''Stephanoceras'' (meaning ''crown horn'') is an extinct genus of Stephanoceratoid ammonite which lived during the Bajocian (Middle Jurassic). It is the type genus of the family Stephanoceratidae. Type species ''Ammonites humphriesianum'' J. de C. Sowerby, 1825, subsequent designation by Buchman, 1898 Selected species *''S. humphriesianum'' (J. de C. Sowerby 1825) - Type species *''S. blagdeni'' (Sowerby) *''S. brodeaei'' (J. Sowerby) *''S. mutabile'' (Quenstedt 1886) *''S. umbilicum'' (Quenstedt 1886) *''S. nodosum'' (Quenstedt 1886) *''S. macrum'' (Quenstedt 1886) *''S. pyritosum'' (Quenstedt 1886) *''S. triplex'' Weisert *''S. freycineti'' (Bayle) *''S. kreter'' (Buckman) *''S. leptogyrale'' (Buckman) *''S. boulderense'' Imlay 1982 *''S. coronatus'' (Bruguiere 1789) *''S. quenstedti'' Кoche 1939 *''S. skidegatense'' Whiteaves 1876 Description ''Stephanoceras'' has an evolute shell, as characteristic of the family, with well-developed ribbing and tube ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
