Elasmosauridae

Elasmosaurus () is a genus of plesiosaur that lived in North America during the Campanian stage of the Late Cretaceous period, at about 80.6 to 77million years ago. The first specimen was discovered in 1867 near Fort Wallace, Kansas, US, and was sent to the American paleontologist Edward Drinker Cope, who named it E.platyurus in 1868. The generic name means "thin-plate reptile", and the specific name means "flat-tailed". Cope originally reconstructed the skeleton of Elasmosaurus with the skull at the end of the tail, an error which was made light of by the paleontologist Othniel Charles Marsh,

Elasmosauridae, often called elasmosaurs or elasmosaurids, is an extinct family of plesiosaurs that lived from the Hauterivian stage of the Early Cretaceous to the Maastrichtian stage of the Late Cretaceous period (c. 130 to 66 mya). The taxon was initially erected in 1869 by Edward Drinker Cope to include the type genus Elasmosaurus with the related Cimoliasaurus, although he did not argue in detail why. Over the following years, many authors recognized this classification on the basis of predominantly postcranial features, becoming one of the three groups in which plesiosaurs were often clas

Styxosaurus is a genus of elasmosaurid plesiosaur that lived during the Late Cretaceous period. Three species are known: S. snowii, S. browni, and S. rezaci. Fossils are known from North America and are mainly found in the Niobrara and Pierre Shale formations. Older fossils are known from the Graneros Shale.

Futabasaurus is a genus of plesiosaur from the Late Cretaceous of Fukushima, Japan. It was described and named in 2006, and was assigned to the family Elasmosauridae. The genus contains one species, F. suzukii.

Thalassomedon (from Greek, thalassa, "sea" and Greek, medon, "lord" or "ruler", meaning "sea lord") is a genus of plesiosaur, named by Welles in 1943.

Mauisaurus ("Māui lizard") is a dubious genus of plesiosaur that lived during the Late Cretaceous period in what is now New Zealand. Numerous specimens have been attributed to this genus in the past, but a 2017 paper restricts Mauisaurus to the lectotype and declares it a nomen dubium.

thumb|Holotype skull of Libonectes morgani Libonectes is an extinct genus of sauropterygian reptile belonging to the plesiosaur order. It is known from specimens found in the Britton Formation of Texas (USA) and the Akrabou Formation of Morocco, which have been dated to the lower Turonian stage of the late Cretaceous period.

Tuarangisaurus ( "ancient" + "lizard") is an extinct genus of elasmosaurid known from New Zealand. The type and only known species is Tuarangisaurus keyesi, named by "Pont" Wiffen, Joan Wiffen and Bill Moisley in 1986. The specific name honours Ian W. Keyes of the New Zealand Geological Survey.

Albertonectes (meaning 'Alberta swimmer') is an extinct genus of large plesiosaurs that lived in North America during the Campanian stage of the Late Cretaceous period, at around 73.5million years ago. The only known species is A. vanderveldei, described in 2012 from an almost complete postcranial skeleton discovered in 2007 near Lethbridge, in the province of Alberta, Canada. Although currently only documented from the holotype, a possible second specimen was discovered in 2015 in the same locality.

Aristonectes (meaning "best swimmer") is an extinct genus of large elasmosaurid plesiosaurs that lived during the Maastrichtian stage of the Late Cretaceous. Two species are known, A. parvidens and A. quiriquinensis, whose fossil remains were discovered in what are now Patagonia and Antarctica. Throughout the 20th century, Aristonectes was a difficult animal for scientists to analyze due to poor fossil preparation, its relationships to other genera were uncertain. After subsequent revisions and discoveries carried out from the beginning of the 21st century, Aristonectes is now recognised as th

Hydrotherosaurus (meaning "fisherman lizard") is an extinct genus of elasmosaurid plesiosaur from the Upper Cretaceous (Maastrichtian stage) Moreno Formation of Fresno County, California, USA. The only known species, H. alexandrae, was named for Annie Montague Alexander in 1943 by Samuel Paul Welles.

Kaiwhekea () is an extinct genus of plesiosaur from the Late Cretaceous (Maastrichtian age) of what is now New Zealand.

Fresnosaurus is an extinct genus of plesiosaur from the Late Cretaceous (Maastrichtian stage) of what is now California. The type species is Fresnosaurus drescheri, first described by Welles in 1943. The generic name Fresnosaurus honors Fresno County, while the specific name honors Arthur Drescher.

Scanisaurus is a dubious genus of plesiosaur that lived in what is now Sweden and Russia during the Campanian stage of the Late Cretaceous period. The name Scanisaurus means "Skåne lizard", Skåne being the southernmost province of Sweden, where a majority of the fossils referred to the genus have been recovered. The genus contains one species, S. nazarowi, described in 1911 by Nikolay Bogolyubov as a species of Cimoliasaurus based on a single vertebral centrum discovered near Orenburg, Russia. the species was moved into its own genus by Per-Ove Persson in 1959 after several differences were ob

Woolungasaurus ('Woolunga lizard', named after an Aboriginal mythical reptile, Persson 1960) is a dubious genus of plesiosaur, an extinct marine reptile, belonging to the Elasmosauridae.

Eromangasaurus is an extinct genus of elasmosaurid known from northern Queensland of Australia.

Aphrosaurus is an extinct genus of plesiosaur from the Maastrichtian. The type species is Aphrosaurus furlongi (LACM 2748), named by Welles in 1943. The holotype specimen was discovered in the Moreno Formation in Fresno County, California in 1939 by rancher Frank C. Piava. A second specimen - LACM 2832 - was also found in the same formation and initially diagnosed as a juvenile of the same species, but has since been removed from the genus.

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Callawayasaurus is a genus of plesiosaur from the family Elasmosauridae. When the holotype was first described by Samuel Paul Welles in 1962, it was described as Alzadasaurus colombiensis before being moved into its current genus by Kenneth Carpenter in 1999.

Jucha is an extinct genus of plesiosaur found in the Hauterivian (Early Cretaceous) Klimovka Formation of Russia. The type species, J. squalea, was one of the basalmost and oldest definitive elasmosaurs known to date.

Cimoliasaurus was a plesiosaur that lived during the Late Cretaceous (Maastrichtian) of the eastern United States, with fossils known from New Jersey, North Carolina, and Maryland.

Cardiocorax is an extinct genus of elasmosaurid known from the Late Cretaceous (early Maastrichtian stage) Mocuio Formation of Namibe Province, southern Angola. It contains a single species, Cardiocorax mukulu.

Terminonatator (meaning "last swimmer") is a genus of elasmosaurid plesiosaur from the Late Cretaceous of Saskatchewan, Canada. It is known from a skull and partial skeleton from a young adult, found in the Campanian-age Bearpaw Formation near Notukeu Creek in Ponteix. Terminonatator is currently one of the youngest plesiosaurs from the Western Interior Seaway.

Wapuskanectes is an extinct genus of early elasmosaurid known from Alberta, Canada, in the Albian aged Wabiskaw member of the Clearwater Formation.

Lagenanectes is a genus of elasmosaurid plesiosaur from the Lower Cretaceous, found in Lower Saxony, Germany. The only species, Lagenanectes richterae, was first described in 2017, and is regarded as one of the best-preserved plesiosaur fossils from this geological age in Europe. Lagenanectes is one of the earliest elasmosaurids. The holotype is an incomplete skeleton, comprising large parts of the skull, some neck and tail vertebrae as well as ribs and part of the limbs. A length of about 8 meters (26 feet) has been estimated.

Fluvionectes (meaning "river swimmer", from both Latin and Greek) is a genus of elasmosaurid plesiosaur found in the Dinosaur Park Formation in Alberta, Canada.

Zarafasaura is an extinct genus of elasmosaurid known from the Ouled Abdoun Basin of Morocco. As a relatively small elasmosaur, it would have measured around long and weighed about .

Alexandronectes is a genus of elasmosaurid plesiosaur, a type of long-necked marine reptile, that lived in the oceans of Late Cretaceous New Zealand. It contains one species, A. zealandiensis. Fossils of Alexandronectes were found in the Conway Formation of Canterbury, which can be dated to the Early Maastrichtian stage of the Cretaceous. Fossils of it were found around 1872 near the Waipara River, north of Christchurch, New Zealand.

Morturneria is an extinct genus of plesiosaur from the Late Cretaceous of what is now Antarctica.

Vegasaurus is an extinct genus of elasmosaurid plesiosaur known from the Late Cretaceous (early Maastrichtian stage) Snow Hill Island Formation of Vega Island, Antarctic Peninsula. It contains a single species, Vegasaurus molyi.

Nakonanectes bradti is an elasmosaurid plesiosaur of the late Cretaceous found in 2010 the state of Montana in the United States. It is one of the most recently known elasmosaurids to have lived in North America. Unlike other elasmosaurids, it has a relatively short neck.

Kawanectes (meaning "Kawas swimmer") is an extinct genus of elasmosaurid plesiosaur, a type of long-necked marine reptile, that lived in the marginal marine, probably estuarine, environment of Late Cretaceous Patagonia. The genus contains a single species, Kawanectes lafquenianum, described in 2016 by José P. O'Gorman.

Leurospondylus is an extinct genus of plesiosaur from the Horseshoe Canyon Formation of Canada whose family is currently disputed, but is suggested to be Elasmosauridae.

Goniosaurus is an extinct genus of plesiosaur from the Late Cretaceous (Maastrichtian age) of the Nekum Chalk, in the Netherlands. The only species so far described, G. binkhorsti is represented only by an isolated, compressed and slender tooth described by Christian Erich Hermann von Meyer and a referred tooth and possibly two cervical vertebrae that shows that it was an elasmosaurid, as many other Late Cretaceous plesiosaurs from Europe. The generic name is derived from the Greek gonia, "angle", referring to the fact that the striations meets each other under an angle pointing to below, i.e.

Leivanectes is a genus of plesiosaurs of the family Elasmosauridae known from Late Aptian marine deposits in central Colombia. It contains a single species, L. bernadoi, which was described in 2019.

Wunyelfia is a genus of elasmosaurid plesiosaur, a type of long-necked marine reptile, that lived in the oceans of Late Cretaceous Chile. It contains one species, W. maulensis.

Plesioelasmosaurus is an extinct genus of elasmosaurid plesiosaur from the Late Cretaceous (middle Cenomanian) Greenhorn Limestone of Kansas, United States. The genus contains a single species, P. walkeri, known from a partial skeleton.

Ogmodirus is an extinct genus of plesiosaur found in the Cenomanian-Turonian (Late Cretaceous) Greenhorn Limestone of Kansas. The type species, Ogmodirus martini, was named by Samuel Wendell Williston and Roy Lee Moodie in 1913.

Orophosaurus is an dubious genus of elasmosaurid plesiosaur from the Late Cretaceous of New Mexico.

Alexeyisaurus is an extinct genus of possible plesiosaur known from the upper Triassic (lower-middle Norian age) of Wilczek Formation, Wilczek Land, of Franz Josef Land, Russia. It was first named by A. G. Sennikov and M. S. Arkhangelsky in 2010 and the type species is Alexeyisaurus karnoushenkoi. While considered an elasmosaur in the initial publication, it has been described as a "partial, poorly preserved, and undiagnostic sauropterygian skeleton" in subsequent publications.

REDIRECT Elasmosauridae#Aristonectinae

Traskasaura (meaning "Trask lizard") is an extinct genus of basal elasmosaurid plesiosaurs from the Late Cretaceous (Santonian age) Haslam Formation of British Columbia, Canada. The genus contains a single species, Traskasaura sandrae, known from three partial skeletons. It is the first elasmosaurid discovered in and named from British Columbia.

Chubutinectes (meaning "Chubut swimmer") is an extinct genus of elasmosaurid plesiosaur from the Late Cretaceous La Colonia Formation of Argentina. The genus contains a single species, C. carmeloi, known from a partial skeleton and associated gastroliths.

Marambionectes (meaning "Marambio Island swimmer") is an extinct genus of weddellonectian elasmosaurid plesiosaur from the Late Cretaceous López de Bertodano Formation of Antarctica. The genus contains a single species, M. molinai, known from a partial skeleton.