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Psiloceratoidea
Psiloceratoidea is a superfamily of Early Jurassic ammonoid cephalopods proposed by Hyatt in 1867, assigned to the order Ammonitida. They were very successful during Hettangian and Sinemurian. Last of them, family Cymbitidae and genera ''Hypoxynoticeras'' and ''Radstockiceras'' survived into Early Pliensbachian. Psiloceratoidea is probably derived from the family Ussuritidae, which were Triassic members of Phylloceratoidea. Similar to their ancestors, Psiloceratidae kept smooth, rounded venter for whole of their life. Schlotheimiidae were different, as they had ventral chevrons. Rest of the families had angular venter, or keel for at least part of their ontogeny. Most of the members of this superfamily had only simple ribs, but few of them have evolved also secondary ribbing. While some members are involute and some Oxynoticeratidae were oxycone, most of the species were evolute. Families *Psiloceratidae - Evolute shells with simple, or missing ribs. An venter, there is no o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Psiloceratoidea
Psiloceratoidea is a superfamily of Early Jurassic ammonoid cephalopods proposed by Hyatt in 1867, assigned to the order Ammonitida. They were very successful during Hettangian and Sinemurian. Last of them, family Cymbitidae and genera ''Hypoxynoticeras'' and ''Radstockiceras'' survived into Early Pliensbachian. Psiloceratoidea is probably derived from the family Ussuritidae, which were Triassic members of Phylloceratoidea. Similar to their ancestors, Psiloceratidae kept smooth, rounded venter for whole of their life. Schlotheimiidae were different, as they had ventral chevrons. Rest of the families had angular venter, or keel for at least part of their ontogeny. Most of the members of this superfamily had only simple ribs, but few of them have evolved also secondary ribbing. While some members are involute and some Oxynoticeratidae were oxycone, most of the species were evolute. Families *Psiloceratidae - Evolute shells with simple, or missing ribs. An venter, there is no o ... [...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] |
Cymbitidae
Cymbitidae is family of ammonite that lived during Sinemurian and Pliensbachian stages of Lower Jurassic. They have probably evolved from Arietitidae Arietitidae is a family of true ammonites that make up part of the superfamily Psiloceratoidea, named after the type genus ''Arietites''. They comprise medium-size to large or gigantic genera which in general are strongly ribbed, tuberculate in s .... Description Ammonites belonging to this family had shells with sphaeroconic involute inner whorls that later during ontogeny become evolute and last whorl is highly eccentric. They were small and mostly less than 2 cm in diameter. Venter is smooth, fastigate or rounded. There was constriction on aperture. Ornamentation was weak, as shell was smooth or plicate and only rarely there were lateral tubercules. Genera Cymbitidae is probably monogeneric family. It is named after genus '' Cymbites'' Neumayr, 1878. One more genus has been added there and it is '' Hyerifalchia'' Fucini, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxynoticeratidae
Oxynoticeratidae is a family of true ammonites (order Ammonitida) included in the superfamily Psiloceratoidea. Oxynoticeratids have a broad, worldwide distribution but a narrow stratigraphic one, being known only from the Upper Sinemurian and Lower Pliensbachian,Sepkoski, JacSepkoski's Online Genus Database – Cephalopoda during which their shells changed little in form. Genera *''Cheltonia'' Buckman, 1904 *''Gleviceras'' Buckman, 1918 *''Hypoxynoticeras'' Spath, 1925 *''Oxynoticeras'' Hyatt, 1875 *''Paracymbites'' Spath, 1925 *''Paroxynoticeras'' Pia, 1914 *''Radstockiceras'' Buckman, 1918 *''Slatterites'' Spath, 1923 Description These cephalopds, as the other species in the superfamily Psiloceratoidea, are usually characterized by mostly involute, oxyconic shells with narrow venter and compressed, lanceolate whorl section. The suture line is of ammonitic type. Ribbing is feeble, hardly functional and often absent. They have developed shorter body chambers than in the ances ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echioceratidae
''Echioceratidae'' is an extinct family of ammonites that lived during Sinemurian stage of Early Jurassic. Description Ammonites belonging to this family are characterised by serpenticone shells with a keel, which can be surrounded by grooves if a species is densely ribbed and compressed. The whorl section is either circular or has flat sides. Ribs are simple and strong with the exception of '' Leptechioceras'' which instead possessed a strongly compressed, smooth outer whorl. The initial ontogenical stage of these ammonites is typically smooth but very short. Tubercules are represented in a few genera within this group. M. K. Howarth 2013. Treatise on Invertebrate Paleontology, Part L, Revised, Volume 3B, Chapter 4: Psiloceratoidea, Eoderoceratoidea, Hildoceratoidea. Genera and subgenera Following genera are members of this family: * '' Palaeoechioceras'' Spath, 1929 * '' Gagaticeras'' Buckman, 1913 * '' Plesechioceras'' Trueman and Williams, 1925 * '' Orthechioceras'' Trueman ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arietitidae
Arietitidae is a family of true ammonites that make up part of the superfamily Psiloceratoidea, named after the type genus ''Arietites''. They comprise medium-size to large or gigantic genera which in general are strongly ribbed, tuberculate in some, with keeled or grooved and keeled venters, and well differentiated ammonitic sutures. The aptycus is single valved with a shiny, concentrically striated surface. Arietitidae dominated Lower Jurassic, Sinemurian ammonites, worldwide, extending into the lower Pliensbachian. The Arietitidae may have their origin in the Schlotheimiidae if not directly from the Psiloceratidae, and is the probably source for the Oxynoticeratidae Oxynoticeratidae is a family of true ammonites (order Ammonitida) included in the superfamily Psiloceratoidea. Oxynoticeratids have a broad, worldwide distribution but a narrow stratigraphic one, being known only from the Upper Sinemurian and .... References * * Donvan, D.T. and Callomon, J.H. 1981, Class ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schlotheimiidae
Schlotheimiidae is an extinct family of cephalopods belonging to the Ammonite subclass. These cephalopods existed in the Jurassic period. Genera * '' Angulaticeras'' * '' Kammerkarites'' * '' Macrogrammites'' * '' Saxoceras'' * '' Schlotheimia'' * '' Waehneroceras'' Distribution Fossils of species within this family have been found in the 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-J ... rocks of Argentina, Austria, Belgium, Canada, China, France, Germany, Hungary, Indonesia, Italy, Luxembourg, Madagascar, Mexico, Russia, Switzerland, United Kingdom, United States. References Psiloceratoidea Ammonitida families Hettangian first appearances Middle Jurassic extinctions {{Ammonitina-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Psiloceratidae
Psiloceratidae is an extinct family of cephalopods belonging to the ammonite subclass. Description The Psiloceratidae are evolute, smooth or with blunt primary ribbing. The venter is rounded and generally smooth, in some feebly keeled. Sutures are simple with phylloid saddle endings in some. The aptychus is single, found in sutu in Psiloceras Genera * '' Badouxia'' Guex and Taylor, 1976 * ''Caloceras'' * '' Discamphiceras'' * '' Euphyllites'' Wahner, 1898 * '' Franziceras'' Buckman, 1923 * ''Kammerkaroceras'' * ''Laqueoceras'' * '' Murihikuites'' Stevens, 2004 * '' Paradiscamphiceras'' Taylor, 1988 * '' Paraphylloceras'' Salfeld, 1919 * ''Psiloceras'' * ''Psilophyllites'' Distribution Fossils of species within this genus have been found in the Triassic rocks of Canada, in the Jurassic rocks of Argentina, Austria, Canada, China, France, Germany, Hungary, Mexico, New Zealand, Spain), United Kingdom, United States, as well as in the Cretaceous The Cretaceous ( ) is a geological ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypoxynoticeras
''Hypoxynoticeras'' is an extinct genus of lower Jurassic The Early Jurassic Epoch (in chronostratigraphy corresponding to the Lower Jurassic 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&nb ... ammonite that lived during Jamesoni zone of lower Pliensbachian. Animals belonging to this genus had small platycone shells, of which umbilicus made 25—30% of diameter. Keel was strong and ventrolateral shoulders were prominent. It is possible, that it was just a microconch, or juvenile of '' Radstockiceras''. Distribution Fossils belonging to this genus were found in northern Germany, Poland, western Scotland and in England.Pieńkowski, G. (2014). The first Early Jurassic ammonite find in central Poland. Volumina Jurassica, 12(1), 99-104. References Oxynoticeratidae Ammonitida genera Jurassic ammonites of Europe Pliensbachian life {{ammonitina-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radstockiceras
''Radstockiceras'' is an extinct genus of lower Jurassic ammonite that lived from Oxynotum zone of upper Sinemurian to Raricostatum zone of lower Pliensbachian. Shells of these animals were oxycone and involute with umbilicus that took maximum of 12% of diameter in the case of outer whorls. On inner whorls, venter has been sharp, but then it became rounded. Faint ribs had falcoid shape, but sometimes, ribs could absent. Shells could have been large in their size. Suture has been very complex, similar to ''Oxynoticeras'', but culmination at umbilical margin has been missing. Genus has been named after town of Radstock, in Somerset.Schlegelmilch, R. (1992). Die Ammoniten des süddeutschen Lias: ein Bestimmungsbuch für Fossiliensammler und Geologen. Springer Spektrum. Distribution Fossils belonging to this genus are found in Europe, South America, North Africa and Turkey. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Psiloceras Laevis - Naturhistorisches Museum, Braunschweig, Germany - DSC05130
''Psiloceras'' is an extinct genus of ammonite. ''Psiloceras'' is among the earliest known Jurassic ammonites, and the appearance of the earliest ''Psiloceras'' species form the definition for the base of the Jurassic. Unlike most earlier ammonites, which had complex shell shapes and ornamentation, ''Psiloceras'' had a smooth shell. Taxonomy Almost all ammonites, with the sole exemption of a few members of the family Psiloceratidae, including ''Psiloceras'' were wiped out at the Triassic–Jurassic extinction event (201.3 million years ago). Most authors assume that ''Psiloceras'' descended from the Phyllocerataceae. ''P. spelae'' is probably the earliest species of ''Psiloceras''. Biostratigraphic significance The International Commission on Stratigraphy (ICS) has assigned the First Appearance Datum of the ''Psiloceras spela''-group as the defining biological marker for the start of the Hettangian, 201.3 ± 0.2 million years ago, the earliest stage of the Jurassic, with the G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |