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Simolestes Indicus
''Simolestes'' (meaning "hearkening thief") is an extinct pliosaurid genus that lived in the Middle to Late Jurassic. The type specimen, BMNH R. 3319 is an almost complete but crushed skeleton diagnostic to ''Simolestes vorax'', dating back to the Callovian of the Oxford Clay formation, England. The genus is also known from the Callovian and Bajocian of France (''S.keileni''), and the Tithonian of India (''S.indicus''). The referral of these two species to ''Simolestes'' is dubious, however. Description ''Simolestes'' possessed a short, high, and wide skull which was built to resist torsional forces when hunting. The largest specimens of ''S.vorax'' reached approximately in length, if a head to body ratio similar to ''Liopleurodon'' is applied. ''S.keileni'' was larger, with specimens from France suggesting that some individuals grew more than long. ''S. vorax'' and ''S. keileni'' weighed about , respectively. Palaeobiology Like most Pliosaurs, ''Simolestes'' possess ... [...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] |
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] |
Atychodracon
''Atychodracon'' is an extinct genus of rhomaleosaurid plesiosaurian known from the Late Triassic - Early Jurassic boundary (probably early Hettangian stage) of England. It contains a single species, ''Atychodracon megacephalus'', named in 1846 originally as a species of ''Plesiosaurus''. The holotype of ''"P." megacephalus'' was destroyed during a World War II air raid in 1940 and was later replaced with a neotype. The species had a very unstable taxonomic history, being referred to four different genera by various authors until a new genus name was created for it in 2015. Apart from the destroyed holotype and its three partial casts (that survived), a neotype and two additional individuals are currently referred to ''Atychodracon megacephalus'', making it a relatively well represented rhomaleosaurid. History of discovery The type species of ''Atychodracon'' was first described and named by Samuel Stutchbury in January 1846, as a species of the wastebasket taxon ''Plesiosauru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macroplata
''Macroplata'' (meaning "big plate") is an extinct genus of Early Jurassic rhomaleosaurid plesiosaur which grew up to in length and weighed up to . Like other plesiosaurs, ''Macroplata'' probably lived on a diet of fish, using its sharp needle-like teeth to catch prey. Its shoulder bones were fairly large, indicating a powerful forward stroke for fast swimming. ''Macroplata'' also had a relatively long neck, twice the length of the skull, in contrast to pliosaurs. A different species, ''Macroplata longirostris'' (previously called ''Plesiosaurus longirostris''), which lived somewhat later, during the Toarcian stage, was also included in the genus; however, in 2011, Benson ''et al.'' reclassified it as a pliosaurid in the genus ''Hauffiosaurus'', ''H. longirostris''. Description ''Macroplata'' bore an elongated skull, with more than half of its cranial length taken up by a roughly triangular snout. The premaxillae (front upper jaw bones) bear six teeth each, with the first being ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archaeonectrus
''Archaeonectrus'' is an extinction, extinct genus of pliosaur from the Early Jurassic (Sinemurian) of what is now southeastern England. The type species is ''Archaeonectrus'' (originally ''"Plesiosaurus"'') ''rostratus'', first named by Sir Richard Owen in 1865, which was moved to its own genus by N.I. Novozhilov in 1964. It was a relatively small plesiosaur, measuring long. Classification The cladogram below shows ''Archaeonectrus'' phylogenetic position among other plesiosaurs, following Benson ''et al.'' (2012). See also * Timeline of plesiosaur research * List of plesiosaur genera References * Sepkoski, J.J. (2002). "A compendium of fossil marine animal genera". ''Bulletins of American Paleontology'' 363: 1-560. External links ''Archaeonectrus'' in the Paleobiology Database {{Taxonbar, from=Q4785513 Jurassic plesiosaurs of Europe Rhomaleosaurids Fossil taxa described in 1964 Sauropterygian genera ... [...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 Group, 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 species, 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 ''Occitanosaurus''. 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 Dec ... [...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 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 OR1336. NHMUK 49202 was collected at Lyme Regis, of Dorset, from the Hettangian to early Sinemurian-aged beds of the Lower Lias Group. Description NHMUK 49202 possesses plesiomorphic characters, including premaxillae that do not separate the frontals on the midline, narrow cranioquadrate passages and the lack of a constricting groove around t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhomaleosauridae
Rhomaleosauridae is a family of plesiosaurs from the Earliest Jurassic to the latest Middle Jurassic (Hettangian to Callovian stages) of Europe, North America, South America and possibly Asia. Most rhomaleosaurids are known from England, many specifically from lower Blue Lias deposits that date back to the earliest Jurassic, just at the boundary with the Triassic. In fact, to date only two undisputed rhomaleosaurids were named from outside Europe - the closely related '' Borealonectes russelli'' and '' Maresaurus coccai'' from Canada and Argentina, respectively. These two species are also the only Middle Jurassic representatives of the family. Rhomaleosauridae was formally named by Kuhn in 1961, originally proposed to include '' Rhomaleosaurus cramptoni'' and its relatives, which have short necks and large heads relatively to plesiosauroids like ''Elasmosaurus'' and ''Plesiosaurus'', but longer necks and smaller heads relatively to advanced pliosaurids like ''Pliosaurus'' and '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cladogram
A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to descendants, nor does it show how much they have changed, so many differing evolutionary trees can be consistent with the same cladogram. A cladogram uses lines that branch off in different directions ending at a clade, a group of organisms with a last common ancestor. There are many shapes of cladograms but they all have lines that branch off from other lines. The lines can be traced back to where they branch off. These branching off points represent a hypothetical ancestor (not an actual entity) which can be inferred to exhibit the traits shared among the terminal taxa above it. This hypothetical ancestor might then provide clues about the order of evolution of various features, adaptation, and other evolutionary narratives about ance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pachycostasaurus
''Pachycostasaurus'' (meaning 'thick-ribbed lizard') is an extinct Pliosauroid from the Oxford Clay formation of Peterborough, England. History and naming The holotype fossil of Pachycostasaurus was discovered by Alan Dawn, an amateur geologist and museum volunteer, in what is now a quarry in Peterborough. The fossil was described in 1997 by Palaeontologists Arthur Cruickshank, David Martill and Leslie Noè, due to its distinct set of features not present in contemporary pliosaurids ''Liopleurodon'' and '' Simolestes.'' Description The type species, ''P. dawni'', is represented by a single near complete specimen (PETMG R338) which was approximately long and weighed . Perhaps the most defining feature of this genus is the large, pachyostic ribs and gastralia described as ‘sausage-like’ in profile. Pachyostosis is known from a number of Pliosaurid genera (for example ''Monquirasaurus''), and is present in modern animals such as Sirenians (Dugong and Manatees). This robust, b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammonites
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 Pomp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
