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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] |
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] |
Rhomaleosaurus Cramptoni
''Rhomaleosaurus'' (meaning "strong lizard") is an extinct genus of Early Jurassic (Toarcian age, about 183 to 175.6 million years ago) rhomaleosaurid pliosauroid known from Northamptonshire and from Yorkshire of the United Kingdom. It was first named by Harry Seeley in 1874 and the type species is ''Rhomaleosaurus cramptoni''. It was one of the earliest large marine reptile predators which hunted in the seas of Mesozoic era, with the type species ''R. cramptoni'' measuring long and weighing . Like other pliosaurs, ''Rhomaleosaurus'' fed on ichthyosaurs, ammonites and other plesiosaurs. Species ''R. cramptoni'' In July 1848, a fossil of a large plesiosaur was unearthed in an Alum quarry at Kettleness, near Whitby, in Yorkshire, England. It was collected from the ''A. bifrons'' ammonite zone of the Whitby Mudstone Formation, dating to the early Toarcian age, about 183 to 180 million years ago. The complete skeleton which preserved the skull, NMING F8785, was kept for five ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhomaleosaurus
''Rhomaleosaurus'' (meaning "strong lizard") is an extinct genus of Early Jurassic (Toarcian age, about 183 to 175.6 million years ago) rhomaleosaurid pliosauroid known from Northamptonshire and from Yorkshire of the United Kingdom. It was first named by Harry Seeley in 1874 and the type species is ''Rhomaleosaurus cramptoni''. It was one of the earliest large marine reptile predators which hunted in the seas of Mesozoic era, with the type species ''R. cramptoni'' measuring long and weighing . Like other pliosaurs, ''Rhomaleosaurus'' fed on ichthyosaurs, ammonites and other plesiosaurs. Species ''R. cramptoni'' In July 1848, a fossil of a large plesiosaur was unearthed in an Alum quarry at Kettleness, near Whitby, in Yorkshire, England. It was collected from the ''A. bifrons'' ammonite zone of the Whitby Mudstone Formation, dating to the early Toarcian age, about 183 to 180 million years ago. The complete skeleton which preserved the skull, NMING F8785, was kept for five ... [...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] |
Meyerasaurus
''Meyerasaurus'' is an extinct genus of rhomaleosaurid known from Holzmaden, Baden-Württemberg of southwestern Germany. Description ''Meyerasaurus'' is known from the holotype SMNS 12478, articulated and complete skeleton which preserved the skull, exposed in ventral view. It has a skull length of , a body length of and a body mass of . It was collected from the ''Harpoceras elegantulum-falciferum'' ammonoid subzones, ''Harpoceras falcifer'' zone, of the famous Posidonien-Schiefer lagerstätte (Posidonia Shale), dating to the early Toarcian stage of the Early Jurassic, about 183-180 million years ago. Etymology ''Meyerasaurus'' was first named by Adam S. Smith and Peggy Vincent in 2010 and the type species is ''Meyerasaurus victor''. It was originally classified as a species of ''Plesiosaurus'', later as the second named species of ''Thaumatosaurus'' (defunct name, meaning "wonder reptile") and ultimately as a species of ''Eurycleidus'' or ''Rhomaleosaurus''. The gene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eurycleidus
''Eurycleidus'' is an extinct genus of large-bodied rhomaleosaurid known from the Early Jurassic period (most likely earliest Hettangian stage) of the United Kingdom. It contains a single species, ''E. arcuatus''. Like other plesiosaurs, ''Eurycleidus'' 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. Phylogeny Most phylogenetic analyses find the type species of the genus, ''Eurycleidus arcuatus'', to be a relatively basal rhomaleosaurid. A second species, ''E. megacephalus'' (Stutchbury, 1846 riginally ''Rhomaleosaurus megacephalus''">Rhomaleosaurus.html" ;"title="riginally ''Rhomaleosaurus">riginally ''Rhomaleosaurus megacephalus'', was reassigned to this genus by Smith (2007). However, most analyses find ''E. megacephalus'' to represent an unnamed genus, which is distinct from both ''Eurycleidus'' and ''Rhomaleosaurus''. ''E. megacephalus'' was move ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maresaurus
''Maresaurus'' is an extinct genus of plesiosaur from the Middle Jurassic (Bajocian) Los Molles Formation of Argentina. The type species, ''Maresaurus coccai'', was named by Gasparini in 1997. Recent phylogenetic analysis found ''Maresaurus'' to be a rhomaleosaurid.Smith AS, Dyke GJ. 2008. The skull of the giant predatory pliosaur ''Rhomaleosaurus cramptoni'': implications for plesiosaur phylogenetics. ''Naturwissenschaften'' e-published 2008. It was about long and weighed . See also * List of plesiosaur genera * Timeline of plesiosaur research This timeline of plesiosaur research is a chronologically ordered list of important fossil discoveries, controversies of interpretation, taxonomic revisions, and cultural portrayals of plesiosaurs, an order of marine reptiles that flourished duri ... References External links * Smith, Adam S. and Dyke, Gareth J. (2008)The skull of the giant predatory pliosaur ''Rhomaleosaurus cramptoni'': implications for plesiosaur phylogenet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blue Lias
The Blue Lias is a geological formation in southern, eastern and western England and parts of South Wales, part of the Lias Group. The Blue Lias consists of a sequence of limestone and shale layers, laid down in latest Triassic and early Jurassic times, between 195 and 200 million years ago. The Blue Lias is famous for its fossils, especially ammonites. Its age corresponds to the Rhaetian to lower Sinemurian stages of the geological timescale, thus fully including the Hettangian stage. It is the lowest of the three divisions of the Lower Jurassic period and, as such, is also given the name ''Lower Lias''. Stratigraphically it can be subdivided into three members: the Wilmcote Limestone, Saltford Shale and Rugby Limestone. Lithology and facies The Blue Lias comprises decimetre scale alternations of argillaceous limestone and mudstone. These alternations are caused by short-term climatic variations during the Early Jurassic attributed to orbital forcing (Milankovitch cycles). Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Jurassic
The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-Jurassic extinction event, 201.3 Ma (million years ago), and ends at the start of the Middle Jurassic 174.1 Ma. Certain rocks of marine origin of this age in Europe are called "Lias Group, Lias" and that name was used for the period, as well, in 19th-century geology. In southern Germany rocks of this age are called Black Jurassic. Origin of the name Lias There are two possible origins for the name Lias: the first reason is it was taken by a geologist from an England, English quarryman's dialect pronunciation of the word "layers"; secondly, sloops from north Cornwall, Cornish ports such as Bude would sail across the Bristol Channel to the Vale of Glamorgan to load up with rock from coastal limestone quarries (lias limestone from S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sthenarosaurus
''Sthenarosaurus'' (meaning "strong lizard") is an extinct genus of rhomaleosaurid pliosauroid discovered in the Toarcian-aged ' Main Alum Shale' (Commune subzone of Bifrons zone)Sepkoski, JacSepkoski's Online Genus Database – Cephalopoda/ref> in Whitby, England. The type species, ''S. dawkinsi'', was named and described in 1909.D. M. S. Watson. 1909. IV. A preliminary note on two new genera of upper Liassic plesiosaurs. ''Memoirs and Proceedings of the Manchester Literary and Philosophical Society'' 54(4):1-28 The type specimen is MMUM LL 8023, a set of postcrania discovered in Whitby. Other indeterminate specimens are known, including a pectoral girdle (pictured in taxobox) described in 1911. Description The holotype is known from an incomplete skeleton with no skull. A precise reconstruction is not possible, but it is assumed that ''Sthenarosaurus'' was a small plesiosaur, reaching up to long when fully grown. The coracoids were short and thick, while the pelvis was broad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stratesaurus
''Stratesaurus'' is an extinct genus of small-bodied rhomaleosaurid plesiosaur known from the Early Jurassic period (most likely earliest Hettangian stage) of the United Kingdom. It contains a single species, ''S. taylori''. It was a small plesiosaur, with a skull length of and a body length of . Discovery ''Stratesaurus'' is known from the holotype specimen OUMNH J.10337, a dorsoventrally crushed but nearly complete skull, and three-dimensionally preserved partial postcranial skeleton including anterior cervical and pectoral vertebrae, a partial hindlimb and ilium. GSM 26035 was referred to ''S. taylori'' because it shares one autapomorphy and other characters with the holotype specimen. It consists of a skull and some anterior cervical vertebrae. AGT 11 was also referred to ''S. taylori''. Although it does nor show the autapomorphies of ''S. taylori'', it is indistinguishable from both OUMNH J.10337 and GSM 26035, and it is possible to distinguish i ... [...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] |
