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Peltoceras
''Peltoceras'' is an extinct ammonite genus from the aspidoceratid subfamily Peltoceratinae that lived during the later part of the Middle Jurassic (U Callovian In the geologic timescale, the Callovian is an age and stage in the Middle Jurassic, lasting between 166.1 ± 4.0 Ma (million years ago) and 163.5 ± 4.0 Ma. It is the last stage of the Middle Jurassic, following the Bathonian and preceding the ...). The shell of ''Peltoceras'' is evolute with whorls hardly embracing, so that all whorls are mostly exposed. The outer rim, which is known as the venter, aligning with the lower part or belly of the animal, is nearly flat. Inner whorls have strong ribs that bifurcate and trifurcate on the ventral margin. The outer whorls have large simple ribs and two rows of massive lateral tubercles, the outer row developing first. References * Arkell, et al., 1957. Mesozoic Ammonoidea; Treatise on Invertebrate Paleontology, Part L. (Ammonoidea) p. L335-336. Geol Soc of America ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Callovian
In the geologic timescale, the Callovian is an age and stage in the Middle Jurassic, lasting between 166.1 ± 4.0 Ma (million years ago) and 163.5 ± 4.0 Ma. It is the last stage of the Middle Jurassic, following the Bathonian and preceding the Oxfordian. Stratigraphic definitions The Callovian Stage was first described by French palaeontologist Alcide d'Orbigny in 1852. Its name derives from the latinized name for Kellaways Bridge, a small hamlet 3 km north-east of Chippenham, Wiltshire, England. The base of the Callovian is defined as the place in the stratigraphic column where the ammonite genus ''Kepplerites'' first appears, which is the base of the biozone of '' Macrocephalites herveyi''. A global reference profile (a GSSP) for the base had in 2009 not yet been assigned. The top of the Callovian (the base of the Oxfordian) is at the first appearance of ammonite species '' Brightia thuouxensis''. Subdivision The Callovian is often subdivided into three substages ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peltoceratinae
The Peltoceratinae comprise a subfamily in the Aspidoceratidae, (middle and upper Jurassic perisphinctacean ammonites). Genera in the Peltoceratinae have sharply ribbed inner whorls and outer whorls that bear spines or tubercles, or have coarse simple ribs. Among these are giant forms with simple peristomes (aperture openings) that occur along with smaller forms with lappets. Derivation of the Peltoceratinae seems most likely to be from the Pseudoperisphinctinae. References *Arkell et al., 1957. Mesozoic Ammonoidea. Treatise on Invertebrate Paleontology, Part L (Ammonoidea). Geol Soc of America and Univ Kansas Press. Jurassic ammonites Aspidoceratidae {{Ammonitina-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Callovian Life
In the geologic timescale, the Callovian is an age and stage in the Middle Jurassic, lasting between 166.1 ± 4.0 Ma (million years ago) and 163.5 ± 4.0 Ma. It is the last stage of the Middle Jurassic, following the Bathonian and preceding the Oxfordian. Stratigraphic definitions The Callovian Stage was first described by French palaeontologist Alcide d'Orbigny in 1852. Its name derives from the latinized name for Kellaways Bridge, a small hamlet 3 km north-east of Chippenham, Wiltshire, England. The base of the Callovian is defined as the place in the stratigraphic column where the ammonite genus ''Kepplerites'' first appears, which is the base of the biozone of '' Macrocephalites herveyi''. A global reference profile (a GSSP) for the base had in 2009 not yet been assigned. The top of the Callovian (the base of the Oxfordian) is at the first appearance of ammonite species '' Brightia thuouxensis''. Subdivision The Callovian is often subdivided into three substages ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aspidoceratidae
The Aspidoceratidae comprise a family of middle and upper Jurassic ammonites that make up part of the superfamily Perisphinctoidea, characterized by evolute shells, commonly stocky, that tend to develop tubercles. The Aspidoceratidae are thought to be derived from the Perisphinctidae and have been subdivided into three subfamilies, the Aspidoceratinae, Peltoceratinae, and Simoceratinae. Subfamilies and genera * Aspidoceratinae Zittel 1895 ** '' Aspidoceras'' ** '' Chinamecaceras'' Cantu-Chapa 2006 ** ''Epaspidoceras'' ** '' Euaspidoceras'' ** ''Orthaspidoceras'' * Peltoceratinae Spath 1924 ** ''Peltoceras'' ** '' Peltoceratoides'' ** ''Rursiceras'' * Simoceratinae The Simoceratinae is a subfamily in the Aspidoceratidae The Aspidoceratidae comprise a family of middle and upper Jurassic ammonites that make up part of the superfamily Perisphinctoidea, characterized by evolute shells, commonly stocky, tha ... ** '' Simoceras'' ** '' Virgatosimoceras'' References * Arkel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Matmor Formation
The Matmor Formation is a geologic formation of up to thick, that is exposed in Hamakhtesh Hagadol in southern Israel. The Matmor Formation contains fossils from a Jurassic equatorial shallow marine environment. Bivalves, gastropods, sponges, corals, echinoderms, and sclerobionts are present in the Matmor Formation to various degrees (Wilson et al., 2010). The stratigraphy of the Matmor Formation consists of alternating layers of limestone and marl (Hirsch and Roded, 1996). Stratigraphy The Iraq Petroleum Company originally described the Jurassic sequence in Hamakhtesh Hagadol of Israel in the 1930s (Hudson, 1958). These findings were later described and published by Blake (1935). Shaw (1947) published a limited summary of the stratigraphy. Hudson (1958) later subdivided the rocks into the Callovian, Divesian, Argovian, Sequanim biostratigraphic stages. In 1963, Goldberg subdivided the section into the Zohar, Kidod and Be'er Sheva Formations. Goldberg (1963) further divi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Makhtesh Gadol
HaMakhtesh HaGadol ( he, הַמַּכְתֵּשׁ הַגָּדוֹל, ''lit.'' The Big Crater) is a makhtesh, a geological erosional landform of Israel's Negev desert. It measures 5 x 10 km. A makhtesh has steep walls of resistant rock surrounding a deep closed valley. One of five makhteshim in Israel and seven in the world, HaMakhtesh HaGadol is the second largest, being exceptional in that it is drained by one river, Nahal Hatira. Makatesh Gadol was discovered and named before Makhtesh Ramon which is the largest Makhtesh in Israel. HaMakhtesh HaGadol is near Yeruham, Israel's first development town, established in the early days of the state. The location was chosen because the region was thought to be rich in natural resources. See also *Makhtesh * Makhtesh Ramon *Makhtesh Katan HaMakhtesh HaKatan ( he, הַמַּכְתֵּשׁ הַקָּטָן, ''lit.'' The Small Crater) is a makhtesh, a geological erosional landform of Israel's Negev desert. One of five makhteshi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammonitida
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] |
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] |
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] |
Ammonites Of Europe
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 near Pompe ... [...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] |
