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Tatenectes
''Tatenectes'' is a genus of cryptoclidid plesiosaur known from the Upper Jurassic of Wyoming. Its remains were recovered from the Redwater Shale Member of the Sundance Formation, and initially described as a new species of '' Cimoliosaurus'' by Wilbur Clinton Knight in 1900. It was reassigned to '' Tricleidus'' by Maurice G. Mehl in 1912 before being given its own genus by O'Keefe and Wahl in 2003. ''Tatenectes laramiensis'' is the type and only species of ''Tatenectes''. While the original specimen was lost, subsequent discoveries have revealed that ''Tatenectes'' was a very unusual plesiosaur. Its torso had a flattened, boxy cross-section and its gastralia (belly ribs) exhibit pachyostosis (thickening). The total length of ''Tatenectes'' has been estimated at . ''Tatenectes'' is related to '' Kimmerosaurus'', although their taxonomic placement has varied. They were once considered to be close relatives of ''Aristonectes'' in the family Cimoliasauridae or Aristonect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aristonectidae
The Aristonectidae is a taxonomic family of poorly known plesiosaurs from the Jurassic and Cretaceous periods. They are closely related to polycotylid plesiosaurs. The family is made up of ''Tatenectes'', ''Kimmerosaurus'', ''Aristonectes'', and ''Kaiwhekea''. This group was formerly known as the Cimoliasauridae, but since ''Cimoliasaurus'' is indeterminate and quite possibly elasmosaurid, this replacement name was erected. ''Tatenectes'' and ''Kimmerosaurus'' represent an earlier Oxfordian Jurassic radiation from Laurasia, while ''Aristonectes'' and ''Kaiwhekea'' represent a later Cretaceous radiation from Gondwana. Appearance Aristonectidae were characterized by a relatively larger head and shorter neck than the Plesiosauridae and Elasmosauridae. Teeth resemble those of the Plesiosauridae. The group is known only from scanty and fragmentary remains. The formal diagnosis of the clade A clade (), also known as a monophyletic group or natural group, is a group of organis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cimoliosaurus
''Cimoliasaurus'' was a plesiosaur that lived during the Late Cretaceous (Maastrichtian) of New Jersey. It grew up to long and weighed up to . Etymology The name is derived from the Greek , meaning "white chalk", and , meaning "lizard", in reference to the fact that the deposits in which it was found bear a superficial resemblance to the chalk deposits of the Western Interior Seaway. Taxonomic history The name ''Cimoliasaurus magnus'' was coined by Joseph Leidy for ANSP 9235, one anterior and 12 posterior cervical vertebrae collected in Maastrichtian-aged greensand deposits in Burlington County, New Jersey. In his catalogue of plesiosaur and ichthyosaur specimens preserved in the NHM, the British zoologist Richard Lydekker referred several Jurassic and Cretaceous plesiosaur species to ''Cimoliasaurus'', including the new species ''C. richardsoni'' (now considered a species of ''Cryptoclidus'') and ''C. cantabrigiensis'', as well as ''Colymbosaurus'' and a number of previ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kimmerosaurus
''Kimmerosaurus'' ("lizard from Kimmeridge") is an extinct genus of plesiosaur from the family Cryptoclididae. ''Kimmerosaurus'' is most closely related to ''Tatenectes''. Discovery There are very few fossil remains of ''Kimmerosaurus'' known. In fact, nothing has been found to show what ''Kimmerosaurus'' may have looked like below the neck, although the atlas and the axis are similar to those of the plesiosaur ''Colymbosaurus''. It is this lack of any post-cranial fossils, and the bone similarities that has led to the belief that ''Kimmerosaurus'' fossils could be the missing head of ''Colymbosaurus'', a similar plesiosaur with no known skull fossils. The first part of the genus name of ''Kimmerosaurus'' comes from the location of the first ''Kimmerosaurus'' fossils, Kimmeridge Clay deposits of Dorset, England (these deposits are also the root word for the Kimmeridgian stage of the Jurassic period). The second part comes from the Greek word ('), "lizard". Description As ''K ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cimoliasauridae
Elasmosauridae is an extinct family of plesiosaurs, often called elasmosaurs. They had the longest necks of the plesiosaurs and existed from the Hauterivian to the Maastrichtian stages of the Cretaceous, and represented one of the two groups of plesiosaurs present at the end of the Cretaceous alongside Polycotylidae. Their diet mainly consisted of crustaceans and molluscs. Description The earliest elasmosaurids were mid-sized, about . In the Late Cretaceous, elasmosaurids grew as large as , such as ''Styxosaurus'', ''Albertonectes'', and ''Thalassomedon''. Their necks were the longest of all the plesiosaurs, with anywhere between 32 and 76 (''Albertonectes'') cervical vertebrae. They weighed up to several tons. Classification Early three-family classification Though Cope had originally recognized ''Elasmosaurus'' as a plesiosaur, in an 1869 paper he placed it, with ''Cimoliasaurus'' and ''Crymocetus'', in a new order of sauropterygian reptiles. He named the group Streptosauri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptoclididae
Cryptoclididae is a family (biology), family of medium-sized plesiosaurs that existed from the Middle Jurassic to the Early Cretaceous. They had long necks, broad and short skulls and densely packed teeth. They fed on small soft-bodied preys such as small fish and crustaceans. The earliest members of the family appeared during the early Bajocian, and they represented the dominant group of long-necked plesiosaurs during the latter half of the Jurassic. Classification In 2010, two supposed late Cretaceous members of the group were reclassified as other kinds of plesiosauroids. ''Kaiwhekea'' was reclassified to Leptocleididae, and ''Aristonectes'' was transferred to Elasmosauridae. Cladogram based on Ketchum and Benson (2010): References External links palaeos.com Cryptoclidids, Jurassic plesiosaurs Cretaceous plesiosaurs Callovian first appearances Late Cretaceous extinctions Prehistoric reptile families {{Jurassic-reptile-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plesiosaur
The Plesiosauria (; Greek: πλησίος, ''plesios'', meaning "near to" and ''sauros'', meaning "lizard") or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared in the latest Triassic Period, possibly in the Rhaetian stage, about 203 million years ago. They became especially common during the Jurassic Period, thriving until their disappearance due to the Cretaceous–Paleogene extinction event at the end of the Cretaceous Period, about 66 million years ago. They had a worldwide oceanic distribution, and some species at least partly inhabited freshwater environments. Plesiosaurs were among the first fossil reptiles discovered. In the beginning of the nineteenth century, scientists realised how distinctive their build was and they were named as a separate order in 1835. The first plesiosaurian genus, the eponymous ''Plesiosaurus'', was named in 1821. Since then, more than a hundred valid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aristonectes
''Aristonectes'' (meaning 'best swimmer') is an extinct genus of plesiosaur from the Late Cretaceous Paso del Sapo Formation of what is now Argentina, the Quiriquina Formation of Chile and the Lopez de Bertodano Formation of Antarctica. The type species is ''Aristonectes parvidens'', first named by Cabrera in 1941. Description Analysis of a specimen from the Lopez de Bertodano Formation indicates that ''Aristonectes'' was one of the largest plesiosaurs ever to exist, with an estimated body length of and body mass of per Paul and per O'Gorman and his colleagues. Classification ''Aristonectes'' was classified variously since its original 1941 description, but a 2003 review of plesiosaurs from Patagonia conducted by Gasparini ''et al.'' (2003) found that ''Aristonectes'' was most closely related to elasmosaurid plesiosaurs like ''Elasmosaurus''. The authors also considered '' Morturneria'' a junior synonym of ''Aristonectes'' because the former's holotype has unfu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sundance Formation
The Sundance Formation is a western North American sequence of Middle Jurassic to Upper Jurassic age Dating from the Bathonian to the Oxfordian, around 168-157 Ma, It is up to 100 metres thick and consists of marine shale, sandy shale, sandstone, and limestone deposited in the Sundance Sea, an inland sea that covered large parts of western North America during the Middle and early Late Jurassic. Geology The Sundance Formation underlies the western North American Morrison Formation, the most fertile source of dinosaur fossils in the Americas, and is separated by a disconformity from the underlying Middle Jurassic Gypsum Springs Formation. Fossils The Sundance Formation is known for fossils of an extinct species of marine cephalopod, the belemnite '' Pachyteuthis densus'', as well as several extinct species of oyster, including ''Deltoideum'', ''Liostrea'', and ''Gryphaea nebrascensis''. Fossil dinosaur 'footprints' on an ancient ocean shoreline are preserved in the format ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of living fish species are ray-finned fish, belonging to the class Actinopterygii, with around 99% of those being teleosts. The earliest organisms that can be classified as fish were soft-bodied chordates that first appeared during the Cambrian period. Although they lacked a true spine, they possessed notochords which allowed them to be more agile than their invertebrate counterparts. Fish would continue to evolve through the Paleozoic era, diversifying into a wide variety of forms. Many fish of the Paleozoic developed external armor that protected them from predators. The first fish with jaws appeared in the Silurian period, after which many (such as sharks) became formidable marine predators rather than just the prey of arthropods. Mos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turbulence
In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between those layers. Turbulence is commonly observed in everyday phenomena such as surf, fast flowing rivers, billowing storm clouds, or smoke from a chimney, and most fluid flows occurring in nature or created in engineering applications are turbulent. Turbulence is caused by excessive kinetic energy in parts of a fluid flow, which overcomes the damping effect of the fluid's viscosity. For this reason turbulence is commonly realized in low viscosity fluids. In general terms, in turbulent flow, unsteady vortices appear of many sizes which interact with each other, consequently drag due to friction effects increases. This increases the energy needed to pump fluid through a pipe. The onset of turbulence can be predicted by the dimensionless Rey ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles (muscular hydrostats) modified from the primitive molluscan foot. Fishers sometimes call cephalopods "inkfish", referring to their common ability to squirt ink. The study of cephalopods is a branch of malacology known as teuthology. Cephalopods became dominant during the Ordovician period, represented by primitive nautiloids. The class now contains two, only distantly related, extant subclasses: Coleoidea, which includes octopuses, squid, and cuttlefish; and Nautiloidea, represented by ''Nautilus'' and ''Allonautilus''. In the Coleoidea, the molluscan shell has been internalized or is absent, whereas in the Nautiloidea, the external shell remains. About 800 living species of cephalopods have been ident ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holotype
A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several examples, but explicitly designated as the holotype. Under the International Code of Zoological Nomenclature (ICZN), a holotype is one of several kinds of name-bearing types. In the International Code of Nomenclature for algae, fungi, and plants (ICN) and ICZN, the definitions of types are similar in intent but not identical in terminology or underlying concept. For example, the holotype for the butterfly '' Plebejus idas longinus'' is a preserved specimen of that subspecies, held by the Museum of Comparative Zoology at Harvard University. In botany, an isotype is a duplicate of the holotype, where holotype and isotypes are often pieces from the same individual plant or samples from the same gathering. A holotype is not necessarily "typ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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