|Ichthyosaurus breviceps fossil|
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Thunnosauria (Greek for "tuna lizard" - thunnos meaning "tuna" and sauros meaning "lizard") is an extinct clade of parvipelvian ichthyosaurs from the Early Jurassic to the early Late Cretaceous (Hettangian - Cenomanian) of Asia, Australia, Europe, North America, and South America. Named by Ryosuke Motani in 1999, it contains the basal taxa Ichthyosaurus and Stenopterygius and the family Ophthalmosauridae. In thunnosaurs, the fore fin is at least twice as long as the hind fin.
Thunnosauria is a node-based taxon defined in 1999 as "the last common ancestor of Ichthyosaurus communis and Stenopterygius quadriscissus and all of its descendants".The cladogram below follows the topology from a 2010 analysis by Patrick S. Druckenmiller and Erin E. Maxwell.
Ichthyosaurs are large extinct marine reptiles. Ichthyosaurs belong to the order known as Ichthyosauria or Ichthyopterygia. Ichthyosaurs lived during the time of the dinosaurs, but formed a separate group from the dinosaurs and may not have been closely related to them.
Ichthyosaurus is a genus of ichthyosaurs from the late Triassic and early Jurassic of Europe and Asia (Indonesia). It is among the best known ichthyosaur genera, as it is the type genus of the order Ichthyosauria.
Ophthalmosaurus is an ichthyosaur of the Middle Jurassic period, named for its extremely large eyes. It had a graceful 6 m (19.5 ft) long dolphin-shaped body, and its almost toothless jaw was well adapted for catching squid. Major fossil finds of this genus have been recorded in Europe and North and South America.
Mixosaurus is an extinct genus of Middle Triassic ichthyosaur. Its fossils have been found near the Italy–Switzerland border and in South China.
Stenopterygius is an extinct genus of thunnosaur ichthyosaur known from Europe. This genus of ichthyosaur grew to a maximum length of 4 meters.
Shastasauridae is an extinct family of Triassic ichthyosaurs that includes the genera Shastasaurus and Himalayasaurus. Many other Triassic ichthyosaurs have been assigned to Shastasauridae in the past, but recent phylogenetic analyses suggest that these species form an evolutionary grade of early ichthyosaurs rather than a true clade or evolutionary grouping that can be called Shastasauridae. Shastasauridae was named by American paleontologist John Campbell Merriam in 1895 along with the newly described genus Shastasaurus. In 1999, Ryosuke Motani erected the clade Shastasauria to include Shastasaurus, Shonisaurus, and several other traditional shastasaurids, defining it as a stem-based taxon including "all merriamosaurians more closely related to Shastasaurus pacificus than to Ichthyosaurus communis." He also redefined Shastasauridae as a node-based taxon including "the last common ancestor of Shastasaurus pacificus and Besanosaurus leptorhynchus, and all its descendants" and Shastasaurinae, which Merriam named in 1908, as a stem taxon including "the last common ancestor of Shastasaurus and Shonisaurus, and all its descendants." In an alternative classification scheme, paleontologist Michael Maisch restricted Shastasauridae to the genus Shastasaurus and placed Shonisaurus and Besanosaurus in their own monotypic families, Shonisauridae and Besanosauridae.
Platypterygius is an ichthyosaur of the family Ophthalmosauridae. It is most closely related to the genera Caypullisaurus and Brachypterygius. The ichthyosaur lived from the Early Cretaceous (Hauterivian) to the earliest Late Cretaceous (Cenomanian) and had a cosmopolitan distribution.
Ophthalmosauridae is an extinct family of thunnosaur ichthyosaurs from the Middle Jurassic to the early Late Cretaceous of Asia, Australia, Europe, North America and South America. Currently, the oldest known ophthalmosaurid is Mollesaurus from the early Bajocian of Argentina. Named by George H. Baur, in 1887, it contains the basal taxa like Ophthalmosaurus. Appleby (1956) named the taxon Ophthalmosauria which was followed by some authors, but these two names are synonyms, Ophthalmosauridae has the priority over Ophthalmosauria.
Mollesaurus is an extinct genus of large ophthalmosaurine ophthalmosaurid ichthyosaur known from northwestern Patagonia of Argentina.
Baptanodon is an ichthyosaur of the Late Jurassic period, named for its extremely large eyes. It had a graceful 6 m (19.5 ft) long dolphin-shaped body, and its almost toothless jaw was well adapted for catching squid. Major fossil finds of this genus have been recorded in North America. The type species, B. natans, was originally named as a species of Ophthalmosaurus in 1879.
Maiaspondylus is an extinct genus of platypterygiine ophthalmosaurid ichthyosaurs known from Northwest Territories of Canada, the Cambridge Greensand of England and the Voronezh Region of Russia.
Parvinatator, from Latin, “parvus” little and “natator” swimmer, is an extinct genus of small ichthyopterygian marine reptile that lived during the Early to Middle Triassic. Its fossils have been found in British Columbia, Canada.
Athabascasaurus is an extinct genus of platypterygiine ophthalmosaurid ichthyosaur known from Alberta, Canada.
Hauffiopteryx is an extinct genus of ichthyosaur known from Germany, Luxembourg and Somerset of the United Kingdom. Two species are known: H. typicus and H. altera.
Macgowania is an extinct genus of parvipelvian ichthyosaur known from British Columbia of Canada.
Parvipelvia is an extinct clade of euichthyosaur ichthyosaurs that existed from the Late Triassic to the early Late Cretaceous of Asia, Australia, Europe, North America and South America. Named by Ryosuke Motani, in 1999, it contains the basal taxa like Macgowania and Hudsonelpidia. Maisch and Matzke (2000) found in their analysis seven synapomorphies that support Parvipelvia. They also found 10 synapomorphies that support the existence of post-Triassic clade of ichthyosaurs, for which the name Neoichthyosauria was found to be available.
Merriamosauria is an extinct clade of ichthyosaurs. It was named by Ryosuke Motani in his 1999 analysis of the relationships of ichthyopterygian marine reptiles and was defined in phylogenetic terms as a stem-based taxon including "the last common ancestor of Shastasaurus pacificus and Ichthyosaurus communis, and all of its descendants." The name honours John Campbell Merriam. Based on this definition, Merriamosauria includes most ichthyosaurs except for several Triassic groups such as the clade Mixosauria, the family Cymbospondylidae, and perhaps the family Toretocnemidae. Merriamosaurs are characterized by features in their pectoral girdles and limb bones, including an extensive connection between the scapula and the coracoid bone, the absence of the first metacarpal and the absence of a pisiform bone.
This timeline of ichthyosaur research is a chronological listing of events in the history of paleontology focused on the ichthyosauromorphs, a group of secondarily aquatic marine reptiles whose later members superficially resembled dolphins, sharks, or swordfish. Scientists have documented ichthyosaur fossils at least as far back as the late 17th century. At that time, a scholar named Edward Lhwyd published a book on British fossils that misattributed some ichthyosaur vertebrae to actual fishes; their true nature was not recognized until the 19th century. In 1811, a boy named Joseph Anning discovered the first ichthyosaur fossils that would come to be scientifically recognized as such. His sister Mary would later find the rest of its skeleton and would go on to become a respected fossil collector and paleontologist in her own right.
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