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Saxoceras Portlocki
''Saxoceras'' is a genus of very evolute schlotheimiid ammonoids from the Lower Jurassic. The shell of ''Saxoceras'' is discoidal, bearing strong, generally straight ribs that arise on the umbilical shoulder and thicken in the middle of the venter. Similar ''Waehneroceras ''Waehneroceras'' is an extinct genus of cephalopod belonging to the Ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, ar ...'' has ribs that curve forward as they approach the venter, and '' Kammerkarites'' has finer ribs with secondaries. Both are also evolute schlotheimiids with all whorls exposed. '' Epamminites'' of the Arietitidae is similar from the side but has a smooth band running along the venter with a median keel. Distribution British Columbia, France and Alaska [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saxoceras Portlocki
''Saxoceras'' is a genus of very evolute schlotheimiid ammonoids from the Lower Jurassic. The shell of ''Saxoceras'' is discoidal, bearing strong, generally straight ribs that arise on the umbilical shoulder and thicken in the middle of the venter. Similar ''Waehneroceras ''Waehneroceras'' is an extinct genus of cephalopod belonging to the Ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, ar ...'' has ribs that curve forward as they approach the venter, and '' Kammerkarites'' has finer ribs with secondaries. Both are also evolute schlotheimiids with all whorls exposed. '' Epamminites'' of the Arietitidae is similar from the side but has a smooth band running along the venter with a median keel. Distribution British Columbia, France and Alaska [...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] |
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 (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" 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 English quarryman's dialect pronunciation of the word "layers"; secondly, sloops from north 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 South Wales was used throughout North Devon/North Cornwall as it con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Waehneroceras
''Waehneroceras'' is an extinct genus of cephalopod belonging to the Ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ... subclass. Distribution Jurassic of Argentina, Austria, Canada, Hungary and the United Kingdom. References Jurassic ammonites Ammonites of North America Hettangian life Schlotheimiidae Ammonitida genera {{Ammonitina-stub ... [...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] |
Jurassic Ammonites
The Jurassic ( ) is a geologic period and 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 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. The beginning of the Toarcian Stage started around 183 million years ago and is marked by an extinction event associated with widespread oceanic anoxia, ocean acidification, and elevated temperatures likely caused by the eruption of the Karoo-Ferrar large igneous provinces. The end of the Jurassic, however, has no clear boundary with the Cretaceous and is the only boundary between geological periods to remain formally undefined. By the beginning of the Jurassic, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammonitida Genera
Ammonitida is an order of 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 in both. R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
