| Aptychodon Temporal range: Late Cretaceous, | |
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| Teeth from the holotype of A. cretaceus | |
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| Genus: | †Aptychodon von Reuss, 1855 |
| Type species | |
| †Aptychodon cretaceus von Reuss, 1855 | |
Aptychodon (meaning "unwrinkled tooth") is an extinct genus of plesiosaur from the Late Cretaceous of the Czech Republic. The type species is A. cretaceus. [1]
The holotype consists of incompletely preserved teeth and they were discovered at White Mountain near Prague, Czech Republic. [2] [3] They were then sent to the Prague Museum before von Reuss (1855) described the teeth and created the species Aptychodon cretaceius. [3]
The teeth of Aptychodon are conical and curved towards one side despite mostly being straight. They also measure between 2.5 centimetres (0.98 in) and 13 centimetres (5.1 in) in length. [3]
Aptychodon has been classified as a potential synonym of Polyptychodon interruptus by later authors. [1] Most authors classify Aptychodon within a basal position in Plesiosauria.
Liopleurodon is an extinct genus of carnivorous pliosaurid pliosaurs that lived from the Callovian stage of the Middle Jurassic to the Kimmeridgian stage of the Late Jurassic period. The type species is L. ferox, which is probably the only valid species. Some studies also include the second species L. pachydeirus, but this latter is considered as a probable junior synonym of L. ferox due to its lack of viable diagnosis. As the holotype specimen of L. ferox consists of a single tooth preserving questionable distinctive features, recent studies therefore recommend the necessary identification of a neotype in order to preserve the validity of the genus. Numerous fossil specimens attributed to Liopleurodon, even including numerous skeletons, have been discovered in Europe, Russia, and Mexico. Other additional species were even proposed, but these are currently seen as coming from other pliosaurid genera.
Thalassomedon is a genus of plesiosaur, named by Welles in 1943.
Acanthodes is an extinct genus of acanthodian fish. Species have been found in Europe, North America, and Asia, spanning the Early Carboniferous to the Early Permian, making it one of the youngest known acanthodian genera.
Geosaurus is an extinct genus of marine crocodyliform within the family Metriorhynchidae, that lived during the Late Jurassic and the Early Cretaceous. Geosaurus was a carnivore that spent much, if not all, its life out at sea. No Geosaurus eggs or nests have been discovered, so little is known of the reptile's lifecycle, unlike other large marine reptiles of the Mesozoic, such as plesiosaurs or ichthyosaurs which are known to give birth to live young out at sea. Where Geosaurus mated, whether on land or at sea, is currently unknown. The name Geosaurus means "Mother of Giants lizard", and is derived from the Greek Ge- and σαῦρος -sauros ("lizard"). The name Geosaurus was established by the French naturalist Georges Cuvier in 1824.
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.
Edgarosaurus is a genus of polycotylid plesiosaur from the Thermopolis Shale, containing one species, E. muddi. The type specimen was found in Early Cretaceous rocks in the state of Montana in the United States. At the time, this location was covered by part of the Western Interior Seaway. Edgarosaurus was one of the first polycotylids that evolved to become native to the Western Interior Seaway.
Cretornis is a pterosaur genus from the late Cretaceous period of what is now the Jizera Formation in the Czech Republic, dating to about 92 million years ago. It only contains a single species, Cretornis hlavaci.
Diplovertebron is an extinct genus of embolomere that lived in the Late Carboniferous period (Moscovian), about 310 million years ago. Diplovertebron was a medium-sized animal, around 50 cm in length. Members of the genus inhabited European Carboniferous swamps in what is now the Czech Republic. They were closely related to larger swamp-dwelling tetrapods like Proterogyrinus and Anthracosaurus. However, Diplovertebron were much smaller than these large, crocodile-like creatures. Known from a single species, Diplovertebron punctatum, this genus has had a complicated history closely tied to Gephyrostegus, another genus of small, reptile-like amphibians.
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.
Terminonatator 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.
Uronautes is an extinct genus of rhomaleosaurid plesiosaur from the Late Cretaceous Fox Hills Formation of the United States. The type species is U. cetiformis.
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.
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.
Aristonectes 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 the type genus of the subfamily Aristonectinae, a lineage of elasmosaurids characterized by an enlarged skull and a reduced length of the neck.
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.
Sinopliosaurus is a dubious genus of pliosauroid plesiosaur. It lived during the Aptian and Albian stages of the Early Cretaceous of the People's Republic of China - its exact age is unknown. The type species, Sinopliosaurus weiyuanensis, was named and described in 1944 by Yang Zhongjian. One species, "S." fusuiensis, was later shown to be based on teeth from a spinosaurid theropod dinosaur which is now known as Siamosaurus. S. weiyuanensis was considered as a freshwater plesiosaur.
Goniosaurus is an extinct genus of plesiosaur from the Late Cretaceous of the Nekum Chalk, in the Netherlands. The only species so far described, G. binskhorsti is represented only by an isolated, compressed and slender tooth described by Hermman Meyer and a referred tooth and a cervical vertebra that shows that was an elasmosaurid, as many others Late Cretaceous plesiosaurs from Europe.
Seeleyosaurus is an extinct genus of plesiosaur from Germany and possibly also Russia.
Meyerasaurus is an extinct genus of rhomaleosaurid plesiosaur known from the Early Jurassic of Holzmaden, Baden-Württemberg in southwestern Germany.
Thaumatodracon is a genus of rhomaleosaurid pliosaur from the early Jurassic found in the United Kingdom. It contains a single species, named by Adam Smith and Ricardo Araújo in 2017.