Plesiosauroidea 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.
Elasmosaurus is a genus of plesiosaur that lived in North America during the Campanian stage of the Late Cretaceous period, about 80.5 million 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, and became part of their "Bone Wars" rivalry. Only one incomplete Elasmosaurus skeleton is definitely known, consisting of a fragmentary skull, the spine, and the pectoral and pelvic girdles, and a single species is recognized today; other species are now considered invalid or have been moved to other genera.
Kronosaurus is an extinct genus of short-necked pliosaurs that lived during the Early Cretaceous period in what is now Australia. It is a monotypic genus with one species K. queenslandicus, described in 1924 from the Toolebuc Formation in Queensland, Australia. With traditionally attributed fossils indicating a total length of up to 10 meters (33 ft), Kronosaurus may have been among the largest pliosaurs.
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 Plesiosauria or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia.
Liopleurodon is an extinct genus of large, carnivorous marine reptile belonging to the Thalassophonea, a clade of short-necked pliosaurid plesiosaurs. Liopleurodon lived from the Callovian Stage of the Middle Jurassic to the Kimmeridgian stage of the Late Jurassic Period. It was the apex predator of the Middle to Late Jurassic seas that covered Europe. The largest species, L. ferox, is estimated to have grown over 6 metres (20 ft) in length based on a large skull.
Pistosaurus is an extinct genus of aquatic sauropterygian reptile closely related to plesiosaurs. Fossils have been found in France and Germany, and date to the Middle Triassic. It contains a single species, Pistosaurus longaevus. Pistosaurus is known as the oldest "subaquatic flying" reptile on earth.
Peloneustes 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 synonymised with P. philarchus. Some of the material formerly assigned to P. evansi have since been reassigned to "Pliosaurus" andrewsi. Peloneustes is known from many specimens, including some very complete material.
Rhomaleosaurus is an extinct genus of Early Jurassic 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, measuring about 7 metres (23 ft) long. Like other pliosaurs, Rhomaleosaurus fed on ichthyosaurs, ammonites and other plesiosaurs.
Thalassiodracon (tha-LAS-ee-o-DRAY-kon) is an extinct genus of plesiosauroid from the Pliosauridae that was alive during the Late Triassic-Early Jurassic (Rhaetian-Hettangian) and is known exclusively from the Lower Lias of England. The type and only species, is Thalassiodracon (Plesiosaurus) hawkinsi.
Polyptychodon is a genus of pliosaurid found in Middle-Late Cretaceous marine deposits in southern England, France and Argentina. It has been considered a nomen dubium in a 2016 review.
Plesiopterys is an extinct genus of plesiosaur originating from the Posidonienschiefer of Holzmaden, Germany, and lived during the Early Jurassic period. It is thought to be the sister taxon to all other plesiosauroids including the Plesiosaurus, and is placed outside of the Plesiosauroidea group. Plesiopterys wildi is the one known species within the genus, and is 220 centimeters long, or about 7.2 feet, and its body and skull are both relatively small. It possesses a unique combination of both primitive and derived characters, and is currently displayed at the State Museum of Natural History, Germany.
Eoplesiosaurus is an extinct genus of basal plesiosauroid known from the Early Jurassic period of the United Kingdom. It contains a single species, E. antiquior.
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 during the Mesozoic Era. The first scientifically documented plesiosaur fossils were discovered during the early 19th century by Mary Anning. Plesiosaurs were actually discovered and described before dinosaurs. They were also among the first animals to be featured in artistic reconstructions of the ancient world, and therefore among the earliest prehistoric creatures to attract the attention of the lay public. Plesiosaurs were originally thought to be a kind of primitive transitional form between marine life and terrestrial reptiles. However, now plesiosaurs are recognized as highly derived marine reptiles descended from terrestrial ancestors.
Megacephalosaurus is an extinct genus of short-necked pliosaur that inhabited the Western Interior Seaway of North America about 94 to 93 million years ago during the Turonian stage of the Late Cretaceous, containing the single species M. eulerti. It is named after its large head, which is the largest of any plesiosaur in the continent and measures up to 1.75 meters (5.7 ft) in length. Megacephalosaurus was one of the largest marine reptiles of its time with an estimated length of 6–9 meters (20–30 ft). Its long snout and consistently sized teeth suggest that it preferred a diet of smaller-sized prey.
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 has been estimated.
Arminisaurus is a genus of pliosaurid plesiosaur that lived during the Lower Jurassic in present-day Germany. With Westphaliasaurus and Cryonectes, Arminisaurus is only the third plesiosaurian taxon that was described from the Pliensbachian stage. The holotype and only known specimen is a fragmentary skeleton, comprising an incomplete lower jaw, teeth, vertebrae and elements from the pectoral girdle and the paddles. The animal had an estimated body length of 3–4 metres (9.8–13.1 ft).
"Pliosaurus" andrewsi is an extinct species of pliosaurid plesiosaurs that lived during the Callovian stage of the Middle Jurassic, in what is now England. The only known fossils of this taxon were discovered in the Peterborough Member of the Oxford Clay Formation. Other attributed specimens have been discovered in various corners of Eurasia, but these are currently seen as indeterminate or coming from other taxa. The taxonomic history of this animal is quite complex, because several of its fossils were attributed to different genera of pliosaurids, before being concretely named and described in 1960 by Lambert Beverly Tarlo as a species of Pliosaurus. However, although the taxon was found to be valid, subsequent revisions found that it is not part of this genus, and therefore a taxonomic revision must be carried out on this species.
This list of fossil reptiles described in 2024 is a list of new taxa of fossil reptiles that were described during the year 2024, as well as other significant discoveries and events related to reptile paleontology that occurred in 2024.
