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Plesiosauria
The Plesiosauria 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 species have been described. In the early twenty-first century, the number of discoveries ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plesiosaurus
''Plesiosaurus'' (Greek: ' ('), near to + ' ('), lizard) is a genus of extinct, large marine sauropterygian reptile that lived during the Early Jurassic. It is known by nearly complete skeletons from the Lias of England. It is distinguishable by its small head, long and slender neck, broad turtle-like body, a short tail, and two pairs of large, elongated paddles. It lends its name to the order Plesiosauria, of which it is an early, but fairly typical member. It contains only one species, the type, ''Plesiosaurus dolichodeirus''. Other species once assigned to this genus, including ''P. brachypterygius'', ''P. guilielmiimperatoris'', and ''P. tournemirensis'' have been reassigned to new genera, such as '' Hydrorion'', '' Seeleyosaurus'' and '' Microcleidus''. Discovery The first complete skeleton of ''Plesiosaurus'' was discovered by early paleontologist and fossil hunter Mary Anning in Sinemurian (Early Jurassic)-age rocks of the lower Lias Group in December 1823 near Lyme R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plesiosauroidea
Plesiosauroidea (; Greek: 'near, close to' and 'lizard') is an extinct clade of carnivorous marine reptiles. They have the snake-like longest neck to body ratio of any reptile. Plesiosauroids are known from the Jurassic and Cretaceous periods. After their discovery, some plesiosauroids were said to have resembled "a snake threaded through the shell of a turtle", although they had no shell. Plesiosauroidea appeared at the Early Jurassic Period (late Sinemurian stage) and thrived until the K-Pg extinction, at the end of the Cretaceous Period. The oldest confirmed plesiosauroid is ''Plesiosaurus'' itself, as all younger taxa were recently found to be pliosauroids. While they were Mesozoic diapsid reptiles that lived at the same time as dinosaurs, they did not belong to the latter. Gastroliths are frequently found associated with plesiosaurs. History of discovery The first complete plesiosauroid skeletons were found in England by Mary Anning, in the early 19th century, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pliosauroidea
Pliosauroidea is an extinct clade of plesiosaurs, known from the earliest Jurassic to early Late Cretaceous. They are best known for the subclade Thalassophonea, which contained crocodile-like short-necked forms with large heads and massive toothed jaws, commonly known as pliosaurs. More primitive non-thalassophonean pliosauroids resembled plesiosaurs in possessing relatively long necks and smaller heads. They originally included only members of the family Pliosauridae, of the order Plesiosauria, but several other genera and families are now also included, the number and details of which vary according to the classification used. The distinguishing characteristics are a short neck and an elongated head, with larger hind flippers compared to the fore flippers, the opposite of the plesiosaurs. They were carnivorous and their long and powerful jaws carried many sharp, conical teeth. Pliosaurs range from 4 to 10 meters or more in length. Their prey may have included fish, sharks, ic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peloneustes
''Peloneustes'' (meaning ) is a genus of pliosaurid plesiosaur from the Middle Jurassic of England. Its remains are known from the Peterborough Member of the Oxford Clay Formation, which is Callovian in age. It was originally described as a species of ''Plesiosaurus'' by palaeontologist Harry Govier Seeley in 1869, before being given its own genus by naturalist Richard Lydekker in 1889. While many species have been assigned to ''Peloneustes'', ''P. philarchus'' is currently the only one still considered valid, with the others moved to different genera, considered ''nomina dubia'', or Synonym (taxonomy), synonymised with ''P. philarchus''. Some of the material formerly assigned to ''P. evansi'' has since been reassigned to "Pliosaurus" andrewsi, "''Pliosaurus''" ''andrewsi''. ''Peloneustes'' is known from many specimens, including some very complete material. With a total length of , ''Peloneustes'' is not a large pliosaurid. It had a large, triangular skull, which occupied abou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ichthyosauria
Ichthyosauria is an order of large extinct marine reptiles sometimes referred to as "ichthyosaurs", although the term is also used for wider clades in which the order resides. Ichthyosaurians thrived during much of the Mesozoic era; based on fossil evidence, they first appeared around 250 million years ago ( Ma) and at least one species survived until about 90 million years ago, into the Late Cretaceous. During the Early Triassic epoch, ichthyosaurs and other ichthyosauromorphs evolved from a group of unidentified land reptiles that returned to the sea, in a development similar to how the mammalian land-dwelling ancestors of modern-day dolphins and whales returned to the sea millions of years later, which they gradually came to resemble in a case of convergent evolution. Ichthyosaurians were particularly abundant in the Late Triassic and Early Jurassic periods, until they were replaced as the top aquatic predators by another marine reptilian group, the Plesiosauria, in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cretaceous–Paleogene Extinction Event
The Cretaceous–Paleogene (K–Pg) extinction event, also known as the K–T extinction, was the extinction event, mass extinction of three-quarters of the plant and animal species on Earth approximately 66 million years ago. The event caused the extinction of all non-avian dinosaurs. Most other tetrapods weighing more than also became extinct, with the exception of some ectothermic species such as sea turtles and crocodilians. It marked the end of the Cretaceous period, and with it the Mesozoic era, while heralding the beginning of the current era, the Cenozoic. In the geologic record, the K–Pg event is marked by a thin layer of sediment called the Cretaceous–Paleogene boundary, K–Pg boundary or K–T boundary, which can be found throughout the world in marine and terrestrial rocks. The boundary clay shows unusually high levels of the metal iridium, which is more common in asteroids than in the Earth's crust. As originally proposed in 1980 by a team of scientists le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sauropterygia
Sauropterygia ("lizard flippers") is an extinct taxon of diverse, aquatic diapsid reptiles that developed from terrestrial ancestors soon after the end-Permian extinction and flourished during the Triassic before all except for the Plesiosauria became extinct at the end of that period. The plesiosaurs would continue to diversify until the end of the Mesozoic, when they became extinct as part of the end-Cretaceous mass extinction. Sauropterygians are united by a radical adaptation of their pectoral girdle, adapted to support powerful flipper strokes. Some later sauropterygians, such as the pliosaurs, developed a similar mechanism in their pelvis. Other than being diapsids, their affinities to other reptiles have long been contentious. Sometimes suggested to be closely related to turtles, other proposals have considered them most closely related to Lepidosauromorpha or Archosauromorpha, and/or the marine reptile groups Thalattosauria and Ichthyosauromorpha. Origins an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anningasaura
''Anningasaura'' is an extinct genus of basal plesiosaur. It is known from a single type species, ''A. lymense'', discovered in Early Jurassic rocks of Lyme Regis in the United Kingdom. Discovery ''Anningasaura'' is known only from the holotype specimen NHMUK OR 49202, which consists of a complete skull, palate, and mandible, with eight associated cervical vertebrae, including the atlas-axis complex. The partial skeleton came from a juvenile plesiosaur. It was originally referred to ''"Plesiosaurus" macrocephalus'' by Charles William Andrews in 1896, which is otherwise known only from the very young type specimen NHMUK PV R1336. NHMUK OR 49202 was collected at Lyme Regis, of Dorset, from the Hettangian to early Sinemurian-aged beds of the Lower Lias Group. Description NHMUK OR 49202 possesses plesiomorphic characters, including premaxillae that do not separate the frontals on the midline, narrow cranioquadrate passages and the lack of a constricting groo ... [...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 143.1 Mya. The Jurassic constitutes the second and middle period of the Mesozoic, Mesozoic Era as well as the eighth period of the Phanerozoic, Phanerozoic Eon 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 (CAMP). The beginning of the Toarcian Age started around 183 million years ago and is marked by the Toarcian Oceanic Anoxic Event, a global episode of Anoxic event, oceanic anoxia, ocean acidification, and elevated global temperatures associated with extinctions, likely caused by the eruption of the Kar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lindwurmia
''Lindwurmia'' (named after the Lindwurm) is a rhomaleosaurid plesiosaur from the Early Jurassic of Germany. It contains a single species, ''Lindwurmia thiuda''. It was a small plesiosaur, measuring long. Discovery and naming The holotype is an incomplete postcranium; the anterior section of the jaws, sixty-nine vertebrae, a partial pectoral girdle, pelvic girdles, and the right fore- and hindlimbs. It was discovered in the '' Psiloceras johnstoni'' ammonite subzone in the clay quarry of Thiemeke'shen Ziegelei in Halberstadt, Germany in 1899 by Johannes Maak, with the dragline excavator that hit upon the specimen partially destroying it in the process; Maak had the specimen restored by 1900 and it was subsequently sent to the Halberstadt City Museum. The specimen was then described by Theodore Brandes, in 1912 and 1914. In 1912, he assigned the specimen to ''Plesiosaurus ( Thaumatosaurus) aff. megacephalo'', and in 1914 Brandes re-assigned it to just ''Thaumatosaurus aff. m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Termatosaurus
''Termatosaurus'' ("End Lizard", due to its appearance in the End Triassic) is a potentially dubious genus of archosaur known from several tooth specimens. Its remains come from the Upper Triassic of France, England, Germany and Switzerland. ''Termatosaurus'' was once thought to have survived until the Early Jurassic, but the attributed Jurassic remains were redescribed as plesiosaur material. Two species are known of this animal: the type species, ''T. albertii'', named by Meyer and T. Plieninger in 1844, and ''T. crocodilinus'', by Quenstedt (1858). According to Oskar Kuhn, ''Termatosaurus'' is a plesiosaur (of the Rhomaleosauridae), while according to other sources, it is a phytosaur.H. v. Meyer. (1845). System der fossilen Saurier axonomy of fossil saurians ''Neues Jahrbuch für Mineralogie, Geognosie, Geologie und Petrefakten-Kunde'' 1845:278-285 Gallery File:Termatosaurus albertii.JPG, Tooth A tooth (: teeth) is a hard, calcified structure found in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mosasauria
Mosasauria is a clade of aquatic and semiaquatic squamates that lived during the Cretaceous period. Fossils belonging to the group have been found in all continents around the world. Early mosasaurians like dolichosaurs were small long-bodied lizards that inhabited nearshore coastal and freshwater environments; the Late Cretaceous saw the rise of large marine forms, the mosasaurids, which are the clade's best-known members. The clade is defined as all descendants of the last common ancestor of the mosasaur '' Mosasaurus hoffmannii'' and dolichosaurs '' Dolichosaurus'', '' Coniasaurus'', and '' Adriosaurus suessi''. Its placement within the squamate tree is highly controversial. Two prominent hypotheses include the varanoid hypothesis, which holds that mosasaurians are most closely related to monitor lizards, and the pythonomorph hypothesis, which argues for a sister relationship with snakes. A third ophidiomorph hypothesis argues that snakes are members of the Mosasauria ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
