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Oxycerites
''Oxycerites'' is an extinct ammonoid cephalopod belonging to the haploceratoid family, Oppeliidae Oppeliidae are compressed to oxyconic, sculptured Haploceratoidea, either unkeeled, unicarinate, bicarinate, or tricarinate; with sutures in great variety, but ribbing usually more or less falcoid or falcate. The Oppeliidae is the principal famil ..., that lived during the Middle Jurassic. Shells of ''Oxycerites'' are involute, compressed and generally smooth with a sharply rounded venter on the outer rim, deeply impressed dorsum on the inner rim, and a small umbilicus. The living chamber takes up slightly more than half a whorl. ''Oxycerites'' grew to a diameter of at least 17.5 cm, about 7 inches. '' Oppelia'' and '' Oecotraustes'' are similar and closely related forms. ''Oppelia'' is smoother, ''Oecotraustes'' more strongly ribbed Distribution Jurassic of Argentina, France, Germany, Iran, Madagascar, Russia, Saudi Arabia and the United Kingdom References ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oppeliidae
Oppeliidae are compressed to oxyconic, sculptured Haploceratoidea, either unkeeled, unicarinate, bicarinate, or tricarinate; with sutures in great variety, but ribbing usually more or less falcoid or falcate. The Oppeliidae is the principal family of the Haploceratoidea, with the longest duration, extending from the Middle Jurassic (Bajocian) to the Upper Cretaceous (Cenomanian) Their derivation is from the Hildoceratoidea. Subfamilies Nine subfamilies are recognized, the first eight of which are included in the earlier Treatise, Part L. They are the: :Oppeliinae :Hecticoceratinae :Distchoceratinae :Teramelliceratinae :Phlycticeratinae :Streblitinae :Mazapilitinae :Aconeceratinae :Binneyitinae The Binneyitinae was added by Donovan ''et al'', 1981, transferred from the Stephanoceratoidea. References * D.T Donavan, J.H. Callomon, and M.K Howarth. 1981. Classification of the Jurassic Ammonitina. In The Ammonoidea. M.R. House and J.R. Senior, eds. Systematics Assoc. Pub Acad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oppelia
''Oppelia'' is a haploceratoid ammonite and type genus for the Oppeliidae that lived during the 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 co .... Shells of ''Oppelia'' are involute with a small to moderate size umbilicus, bluntly rounded to sharp venter, and deeply impressed dorsum. Sides are generally smooth but may be variously ribbed on the outer flanks. Similar and related genera include '' Oxycerites'' and '' Oecotraustes''. Distribution Jurassic of Germany, Greenland, India, Italy, Madagascar, Mexico, Poland, Spain and the United Kingdom References Ammonitida genera Oppeliidae Jurassic ammonites Ammonites of Europe {{ammonitina-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammonoidea
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) than they are to shelled nautiloids such as the living ''Nautilus'' species. The earliest ammonites appeared during the Devonian, with the last species vanishing during the Cretaceous–Paleogene extinction event. Ammonites are excellent index fossils, and linking the rock layer in which a particular species or genus is found to specific geologic time periods is often possible. Their fossil shells usually take the form of planispirals, although some helically spiraled and nonspiraled forms (known as heteromorphs) have been found. The name "ammonite", from which the scientific term is derived, was inspired by the spiral shape of their fossilized shells, which somewhat resemble tightly coiled rams' horns. Pliny the Elder ( 79 AD nea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haploceratoidea
Haploceratoidea, formerly Haplocerataceae, is an extinct superfamily of Ammonoidea, ammonoid cephalopods belonging to the Ammonitida that unites three families, Strigoceratidae, Oppeliidae, and Haploceratidae, listed below. Haploceratoidea begins with all three families in the lower Middle Jurassic, Bajocian. Strigoceratidae is limited to the Bajocian but Oppeliidae, and Haploceratidae extend through the remaining Jurassic, well into the Cretaceous; the Oppeliidae into the middle Albian, the Haplocertidae only into the Valanginian. Diagnosis Haploceratoidea are typically compressed, discoidal Ammontida that may be keeled or unkeeled, tending to be oxyconic, with usually falcoid or falcate ribbing. The aptychus, aptychi are paired and differ between families and have been found ''in situ'' in e.g. ''Oppelia, Oppelia subrudiata'' and in ''Pseudolissoceras''. Taxonomy The Origin of the Haploceratoidea is undetermined but it is likely all three component families have their beginni ... [...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] |
Body Whorl
The body whorl is part of the morphology of the shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk. In gastropods In gastropods, the body whorl, or last whorl, is the most recently formed and largest whorl (or revolution) of a spiral or helical shell, terminating in the aperture. It is called the "body whorl" because most of the body of the soft parts of the animal fits into this whorl. The proportional size of the body whorl in gastropod shells differs greatly according to the actual shell morphology. For shells in which the rate of whorl expansion of each revolution around the axis is very high, the aperture and the body whorl are large, and the shell tends to be low spired. The shell of the abalone is a good example of this kind of shell. The opposite tendency can sometimes create a high spire with very little whorl increase per revolution. In these instances, e.g. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oecotraustes
''Oecotraustes'' is an extinct cephalopod genus included in the ammonid family Oppeliidae Oppeliidae are compressed to oxyconic, sculptured Haploceratoidea, either unkeeled, unicarinate, bicarinate, or tricarinate; with sutures in great variety, but ribbing usually more or less falcoid or falcate. The Oppeliidae is the principal famil ... and named by Waagen in 1869. The genus lived during the Middle Jurassic. Description The shell of ''Oecotraustes'' is evolute, the outer whorl only moderately embracing the inner whorls, laterally compressed whorl height greater than width. Outer flanks and venter ribbed, ribs sinuous. Distribution Fossils of ''Oecotraustes'' species have been found in Jurassic sediments of Germany, India, Madagascar, Spain, and the United States. References *W.J. Arkell ''et al.'', 1957. Mesozoic Ammonoidea; Treatise on Invertebrate Paleontology, Part L, Ammonoidea. Geological Society of America. Jurassic ammonites Ammonites of Europe Ammonites of ... [...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] |
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] |
