Polistodon | |
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Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Synapsida |
Clade: | Therapsida |
Clade: | Cynodontia |
Family: | † Tritylodontidae |
Genus: | † Polistodon He & Cai, 1984 |
Species: | †P. chuannanensis |
Binomial name | |
†Polistodon chuannanensis He & Cai, 1984 | |
Polistodon is an extinct genus of tritylodonts from the Bajocian or Callovian (Middle Jurassic) of China. [1] It contains one species, P. chuannanensis, which is known from a single skull from the Xiashaximiao Formation. [1] According to one study, it may be a species of the genus Stereognathus . [2]
Oligokyphus is an extinct genus of herbivorous tritylodontid cynodont known from the Late Triassic to Early Jurassic of Europe, Asia and North America.
Tritylodon is an extinct genus of tritylodonts, one of the most advanced group of cynodont therapsids. They lived in the Early Jurassic and possibly Late Triassic periods along with dinosaurs. They also shared many characteristics with mammals, and were once considered mammals because of overall skeleton construction. That was changed due to them retaining the vestigial amniote jawbones and a different skull structure. Tritylodons are now regarded as non-mammalian synapsids.
Proceratosaurus is a genus of carnivorous theropod dinosaur from the Middle Jurassic (Bathonian) of England. It contains a single species. P. bradleyi, known from a mostly complete skull and lower jaws. Proceratosaurus was a small dinosaur, estimated to measure around 3 m (9.8 ft) in length. Its name refers to how it was originally thought to be an ancestor of Ceratosaurus, due to the partially preserved portion of the crest of Proceratosaurus superficially resembling the small crest of Ceratosaurus. Now, however, it is considered a coelurosaur, specifically a member of the family Proceratosauridae, and amongst the earliest known members of the clade Tyrannosauroidea.
Tritylodontidae is an extinct family of small to medium-sized, highly specialized mammal-like cynodonts, with several mammalian traits including erect limbs, endothermy and details of the skeleton. They were the last-known family of the non-mammaliaform synapsids, persisting into the Early Cretaceous.
Calsoyasuchus is a genus of crocodylomorph that lived in the Early Jurassic. Its fossilized remains were found in the Sinemurian-Pliensbachian-age Kayenta Formation on Navajo Nation land in Coconino County, Arizona, United States. Formally described as C. valliceps, it is known from a single incomplete skull which is unusually derived for such an early crocodile relative. This genus was described in 2002 by Ronald Tykoski and colleagues; the specific name means "valley head" and refers to a deep groove along the midline of the nasal bones and frontal bones. It has often been interpreted as the earliest diverging member of Goniopholididae, but other studies have recovered it in various other positions.
The Ulan Malgait Formation is a Late Jurassic geologic formation in Mongolia. Dinosaur remains are among the fossils that have been recovered from the formation, although as of 2004 none have yet been referred to a specific genus.
The Itat Formation is a geologic formation in western Siberia. It was deposited in the Bajocian to Bathonian ages of the Middle Jurassic. Dinosaur remains are among the fossils that have been recovered from the formation, including the proceratosaurid Kileskus, as well as fish, amphibians, mammals and many other vertebrates. The formation is noted for bearing significant coal reserves, with large open pit coal mines extracting lignite from the unit currently in operation.
Yuanotherium minor is an extinct species of cynodonts which existed in China during the Late Jurassic epoch, described from the Shishugou Formation. It is the only species in the genus Yuanotherium.
Kayentatherium is an extinct genus of tritylodontid cynodonts that lived during the Early Jurassic. It is one of two tritylodonts from the Kayenta Formation of northern Arizona, United States.
Yunnanodon is an extinct genus of tritylodontid mammaliamorphs that lived in China during the Sinemurian stage of the Early Jurassic period. Its specific name brevirostre is Latin for "short-beaked".
Bienotheroides is an extinct genus of tritylodontid mammaliamorphs from the Jurassic of China and Mongolia. The genus contains five species, primarily known from cranial remains.
Stereognathus is an extinct genus of tritylodontid cynodonts from the Middle Jurassic of the United Kingdom. There is a single named species: S. ooliticus, named after the Great Oolite deposits of England. A second species, S. hebridicus, was named after the Hebrides in Scotland, where it was found; it was synonymized with S. ooliticus in 2017.
Xenocretosuchus is an extinct genus of tritylodont therapsids from the Aptian Ilek Formation of Siberia, in the Russian Federation. The type species, X. sibiricus, is known only from dental elements, as is X. kolossovi, described from the Batylykh Formation in 2008. Some authors have treated these species as part of the genus Stereognathus, otherwise known from the Middle Jurassic of Britain, but this is rejected by other authors.
Kunminia is a genus of cynodont synapsids from the Early Jurassic (Sinemurian) Lufeng Formation of China.
Montirictus is an extinct genus of tritylodonts known from the Early Cretaceous Kuwajima Formation of Japan. It was among the latest surviving tritylodontids, and is closely related to the earlier Xenocretosuchus from mainland Asia, and the Jurassic Stereognathus from the UK. It may be a species of the genus Stereognathus, but resolution of its affinities conditions upon the discovery of additional material.
Borealestes is a genus of docodontan from the Middle Jurassic of Britain, first discovered on the Isle of Skye near the village of Elgol. It was the earliest mammaliaform from the Mesozoic found and named in Scotland. A second species and was later found in other Middle Jurassic sites in England, but is now shown to be a different genus. A new species, B. cuillinensis was named in 2021, also from Skye.
Shartegodon is an extinct genus of tritylodontid cynodont from late Jurassic Ulan Malgait Formation of Mongolia. The type species, Shartegodon altai, was named in 2017.
Nuurtherium is an extinct genus of tritylodontid cynodonts of the Late Jurassic Ulan Malgait Formation of Mongolia. It contains a single species, N. baruunensis, named by Paúl Velazco and colleagues in 2017.
Pseudotherium is an extinct genus of prozostrodontian cynodonts from the Late Triassic of Argentina. It contains one species, P. argentinus, which was first described in 2019 from remains found in the La Peña Member of the Ischigualasto Formation in the Ischigualasto-Villa Unión Basin.
Fossiomanus is an extinct genus of tritylodontid mammaliamorphs from the Early Cretaceous of China. It includes one species, F. sinensis, which is known from a single nearly complete skeleton from the Aptian Jiufotang Formation. Features of its limbs and vertebrae indicate that Fossiomanus was adapted towards a fossorial lifestyle.