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Orthocormus
''Orthocormus'' is an extinct genus of prehistoric pachycormiform bony fish. It is known from three species found in Late Jurassic (Kimmeridgian) aged plattenkalk deposits in Bavaria, Germany. The species "'' Hypsocormus" tenuirostris'' Woodward 1889 from the late Middle Jurassic (Callovian) Oxford Clay is not closely related to the type species of ''Hypsocormus'', and is more closely related to ''Orthocormus'' + ''Protosphyraena'', and thus has sometimes been referred to in open nomenclature as ''Orthocormus? tenuirostris.'' See also * Prehistoric fish The evolution of fish began about 530 million years ago during the Cambrian explosion. It was during this time that the early chordates developed the skull and the vertebral column, leading to the first craniates and vertebrates. The first fis ... * List of prehistoric bony fish References External links * Pachycormiformes {{Jurassic-fish-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pachycormiformes
Pachycormiformes is an extinct order of marine ray-finned fish known from the Early Jurassic to the end of the Cretaceous. It only includes a single family, Pachycormidae. They were characterized by having serrated pectoral fins (though more recent studies demonstrated that fin shape diversity in this group was high), reduced pelvic fins and a bony rostrum. Their exact relations with other fish are unclear, but they are generally considered to be teleosteomorphs, more closely related to teleosts than to Holostei. Pachycormiformes are morphologically diverse, containing both tuna and swordfish-like carnivorous forms, as well as edentulous suspension-feeding forms, with the latter including the largest ray finned fish known to have existed, ''Leedsichthys,'' with an estimated maximum length of 16 metres. Synapomorphies Pachycormiformes are united by "a compound bone (rostrodermethmoid) forming the anterodorsal border of the mouth; a reduced coronoid process of the mandible; ab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypsocormus
''Hypsocormus'' (from el, ῠ̔́ψος , 'height' and el, κορμός 'timber log') is an extinct genus of pachycormid fish from the Middle to Late Jurassic of Europe. Fossils have been found in Germany, France and the UK. The type species, ''H. insignis'', was originally described by Johann Andreas Wagner in 1860 from the Upper Jurassic plattenkalk limestones of Bavaria, Germany, and placed into the new genus ''Hypsocormus'' by Wagner in a posthumous publication in 1863. A second valid species, ''Hypsocormus posterodorsalis'' was named by Maxwell and colleagues in 2020 from the same deposits. The species "''Hypsocormus macrodon''" Wagner 1863 from the Upper Jurassic of Germany has been moved to a separate genus and renamed '' Simocormus macrolepidotus.'' The species ''"Hypsocormus" tenuirostris'' from the Middle Jurassic of England is more similar to ''Orthocormus'', and thus has often been referred to as ''Orthocormus? tenuirostris.'' ''Hypsocormus'' was a fast-swimming ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxford Clay
The Oxford Clay (or Oxford Clay Formation) is a Jurassic marine sedimentary rock formation underlying much of southeast England, from as far west as Dorset and as far north as Yorkshire. The Oxford Clay Formation dates to the Jurassic, specifically, the Callovian and Oxfordian ages, and comprises two main facies. The lower facies comprises the Peterborough Member, a fossiliferous organic-rich mudstone. This facies and its rocks are commonly known as lower Oxford Clay. The upper facies comprises the middle Oxford Clay, the Stewartby Member, and the upper Oxford Clay, the Weymouth Member. The upper facies is a fossil poor assemblage of calcareous mudstones. Oxford Clay appears at the surface around Oxford, Peterborough and Weymouth and is exposed in many quarries around these areas. The top of the Lower Oxford Clay shows a lithological change, where fissile shale changes to grey mudstone. The Middle and Upper Oxford Clays differ slightly, as they are separated by an argillaceou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bony Fish
Osteichthyes (), popularly referred to as the bony fish, is a diverse superclass of fish that have skeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes, which have skeletons primarily composed of cartilage. The vast majority of fish are members of Osteichthyes, which is an extremely diverse and abundant group consisting of 45 orders, and over 435 families and 28,000 species. It is the largest class of vertebrates in existence today. The group Osteichthyes is divided into the ray-finned fish ( Actinopterygii) and lobe-finned fish (Sarcopterygii). The oldest known fossils of bony fish are about 425 million years old, which are also transitional fossils, showing a tooth pattern that is in between the tooth rows of sharks and bony fishes. Osteichthyes can be compared to Euteleostomi. In paleontology the terms are synonymous. In ichthyology the difference is that Euteleostomi presents a cladistic view which includes the terrestrial tet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 Jurassic constitutes the middle period of the Mesozoic, 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, 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 Anoxic event, oceanic anoxia, ocean acidification, and elevated temperatures likely caused by the eruption of the Karoo-Ferrar, Karoo-Ferrar large igneous provinces. The end of the Jurassic, however, has no clear boundary with the Cretaceous and i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kimmeridgian
In the geologic timescale, the Kimmeridgian is an age in the Late Jurassic Epoch and a stage in the Upper Jurassic Series. It spans the time between 157.3 ± 1.0 Ma and 152.1 ± 0.9 Ma (million years ago). The Kimmeridgian follows the Oxfordian and precedes the Tithonian. Stratigraphic definition The Kimmeridgian Stage takes its name from the village of Kimmeridge on the Dorset coast, England. The name was introduced into the literature by French geologist Alcide d'Orbigny in 1842. The Kimmeridge Clay Formation takes its name from the same type location (although this formation extends from the Kimmeridgian stage of the Upper Jurassic into the Lower Cretaceous). It is the source for about 95% of the petroleum in the North Sea. Historically, the term Kimmeridgian has been used in two different ways. The base of the interval is the same but the top was defined by British stratigraphers as the base of the Portlandian (''sensu anglico'') whereas in France the top was defined as t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plattenkalk
Plattenkalk is a very finely grained limestone chemically precipitated in a stratified water column under conditions where bioturbation does not occur. The reasons for the quiet depositional environment and the processes of sediment accumulation vary greatly among different plattenkalks, but the lack of bioturbation contributes to the creation of thinly bedded, finely laminated, undisturbed limestones where exceptionally detailed fossils or imprints of organisms occur. The Solnhofen Plattenkalk in Bavaria is a famous example where complete skeletons of large marine vertebrates and impressions of soft-bodied animals have been found. Wilkin, J.T.R. (2020) The south German Plattenkalks. Geology Today 36(1): 27-32. https://doi.org/10.1111/gto.12288Lithographic limestone is a type of plattenkalk chosen for its suitable lithography Lithography () is a planographic method of printing originally based on the immiscibility of oil and water. The printing is from a stone (lithographic ... [...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] |
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] |
Protosphyraena
''Protosphyraena'' is a fossil genus of swordfish-like marine fish, that thrived worldwide during the Upper Cretaceous Period (Coniacian-Maastrichtian). Though fossil remains of this taxon have been found in both Europe and Asia, it is perhaps best known from the Smoky Hill Member of the Niobrara Chalk Formation of Kansas (Late Coniacian-Early Campanian). ''Protosphyraena'' was a large fish, averaging 2–3 metres in length. ''Protosphyraena'' shared the Cretaceous oceans with aquatic reptiles, such as mosasaurs and plesiosaurs, as well as with many other species of extinct predatory fish. The name ''Protosphyraena'' is a combination of the Greek word ''protos'' ("early") plus '' Sphyraena'', the genus name for barracuda, as paleontologists initially mistook ''Protosphyraena'' for an ancestral barracuda. Recent research shows that the genus ''Protosphyraena'' is not at all related to the true swordfish-family Xiphiidae, but belongs to the extinct family Pachycormidae. History a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Open Nomenclature
Open nomenclature is a vocabulary of partly informal terms and signs in which a taxonomist may express remarks about their own material. This is in contrast to synonymy lists, in which a taxonomist may express remarks on the work of others. Commonly such remarks take the form of abbreviated taxonomic expressions in biological classification. Usage of open nomenclature There are no strict conventions in open nomenclature concerning which expressions to use or where to place them in the Latin name of a species or other taxon, and this may lead to difficulties of interpretation. However, the most significant unsettled issues concern the way that their meanings are to be interpreted. The International Code of Zoological Nomenclature (ICZN) makes no reference to open nomenclature, leaving its use and meaning open for interpretation by taxonomists. The following are examples of commonly used shorthand in open nomenclature: *Sp. (pl. spp.; short for "species") indicates potentially new ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prehistoric Fish
The evolution of fish began about 530 million years ago during the Cambrian explosion. It was during this time that the early chordates developed the skull and the vertebral column, leading to the first craniates and vertebrates. The first fish lineages belong to the Agnatha, or jawless fish. Early examples include ''Haikouichthys''. During the late Cambrian, eel-like jawless fish called the conodonts, and small mostly armoured fish known as ostracoderms, first appeared. Most jawless fish are now extinct; but the extant lampreys may approximate ancient pre-jawed fish. Lampreys belong to the Cyclostomata, which includes the extant hagfish, and this group may have split early on from other agnathans. The earliest Gnathostomata, jawed vertebrates probably developed during the late Ordovician period. They are first represented in the fossil record from the Silurian by two groups of fish: the armoured fish known as Placodermi, placoderms, which evolved from the ostracoderms; and the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
