Late Triassic extinctions

Conodonts are an extinct group of marine jawless vertebrates belonging to the class Conodonta (from Ancient Greek κῶνος (kōnos), meaning "cone", and ὀδούς (odoús), meaning "tooth"). They are primarily known from their hard, mineralised tooth-like structures called "conodont elements" that in life were present in the oral cavity and used to process food. Rare soft tissue remains suggest that they had elongate eel-like bodies with large eyes. Conodonts were a long-lasting group with over 300 million years of existence from the Cambrian (over 500 million years ago) to the beginning of the Jurassi

Placodonts ("tablet teeth") are an extinct order of marine reptiles that lived during the Triassic period, becoming extinct at the end of the period. They were part of Sauropterygia, the group that includes plesiosaurs. Placodonts were generally between in length, with some of the largest measuring long.

Dicynodontia is an extinct clade of anomodonts, an extinct type of non-mammalian therapsid. Dicynodonts were herbivores that typically bore a pair of tusks, hence their name, which means 'two dog tooth'. Members of the group possessed a horny, typically toothless beak, unique amongst all synapsids. Dicynodonts first appeared in Southern Pangaea during the mid-Permian, ca. 270–260 million years ago, and became globally distributed and the dominant herbivorous animals in the Late Permian, ca. 260–252 Mya. They were devastated by the end-Permian mass extinction that wiped out most other therapsid

Aetosaurs () are heavily armored reptiles belonging to the extinct order Aetosauria (; from Greek, (aetos, "eagle") and (, "lizard")). They were medium- to large-sized omnivorous or herbivorous pseudosuchians, part of the branch of archosaurs more closely related to crocodilians than to birds and non-avian dinosaurs. All known aetosaurs are restricted to the Late Triassic, and in some strata from this time they are among the most abundant fossil vertebrates. They have small heads, upturned snouts, erect limbs, and a body ornamented with four rows of plate-like osteoderms (bony scutes). Aetosau

thumb|right|Anomocephalus thumb|right|Otsheria thumb|right|Aulacocephalodon thumb|right|Kannemeyeria Anomodontia is an extinct group of non-mammalian therapsids from the Permian and Triassic periods. By far the most speciose group are the dicynodonts, a clade of beaked, tusked herbivores. Anomodonts were very diverse during the Middle Permian, including primitive forms like Anomocephalus and Patranomodon and groups like Venyukovioidea and Dromasauria. Dicynodonts became the most successful and abundant of all herbivores in the Late Permian, filling ecological niches ranging from large browsers

Rauisuchidae is a group of large (up to ) predatory Triassic archosaurs. Some disagreement exists over which genera should be included in the Rauisuchidae and which should be in the related Prestosuchidae and Poposauridae, and indeed whether these should even be thought of as separate valid families. Rauisuchidae in the modern sense was defined by Sterling Nesbitt in 2011 as the most inclusive clade containing Rauisuchus tiradentes, but not Prestosuchus chiniquensis, Poposaurus gracilis, or Crocodylus niloticus (the Nile crocodile). In this modern sense, rauisuchids are recovered as members of

Thalattosauria (Greek for "sea lizards") is an extinct order of marine reptiles that lived during the Triassic Period. Thalattosaurs were diverse in size and shape, and are divided into two superfamilies: Askeptosauroidea and Thalattosauroidea.

left|thumb|Skull of Kapes bentoni Procolophonidae is an extinct family of small, lizard-like procolophonian "parareptiles" known from the Late Permian to Late Triassic that were distributed across Pangaea, having been reported from Europe, North America, China, South Africa, South America, Antarctica, and Australia.

Procolophonomorpha is a proposed order containing most groups included within the traditional "Parareptilia." Many papers have applied various definitions to the name, though most of these definitions have since been considered synonymous with modern parareptile clades such as Ankyramorpha and Procolophonia. The current definition of Procolophonomorpha, as defined by Modesto, Scott, & Reisz (2009), is that of a stem-based group containing Procolophon and all taxa more closely related to it than Milleretta. It constitutes a diverse assemblage that includes several lizard-like forms, and more di

Dinodontosaurus (meaning "terrible-toothed lizard") is a genus of dicynodont therapsid. It was medium to large dicynodont of the Triassic (with skull up to long) and had a beak corneum. It lived in the Middle Triassic but disappeared in the Upper Triassic.

Poposauridae is a family of large carnivorous archosaurs which lived alongside dinosaurs during the Late Triassic. They were around long. Poposaurids are known from fossil remains from North and South America. While originally believed to be theropod dinosaurs (they mirrored the theropods in a number of respects, such as features of the skull and bipedal locomotion), cladistic analysis has shown them to be more closely related to crocodiles.

Californosaurus ('California lizard') is an extinct genus of ichthyosaur, an extinct marine reptile, from the Lower Hosselkus Limestone (Carnian, Late Triassic) of California, and also the Muschelkalk (Ladinian, Middle Triassic) of Germany.

Prestosuchidae (in its widest usage) is a polyphyletic grouping of carnivorous archosaurs that lived during the Triassic. They were large active terrestrial apex predators, ranging from around in length. They succeeded the Erythrosuchidae as the largest archosaurs of their time. While resembling erythrosuchids in size and some features of the skull and skeleton, they were more advanced in their erect posture and crocodile-like ankle, indicating more efficient gait. "Prestosuchids" flourished throughout the whole of the middle, and the early part of the late Triassic, and fossils are so far kno

Procolophon (from , 'before' and , 'summit') is a genus of lizard-like procolophonid parareptiles that first appeared in the Early Triassic (Induan) of South Africa, Brazil, and Antarctica. It persisted through the Permian–Triassic extinction event, but went extinct in the beginning of the Early Middle Triassic.

Traversodontidae is an extinct family of herbivorous cynodonts. Traversodonts were primarily Gondwanan, with many species known from Africa and South America. Recently, traversodonts have also been found from Europe and North America. Traversodonts first appeared in the Middle Triassic and diversified in the Late Triassic before going extinct at the end of the epoch. The family Traversodontidae was erected by Friedrich von Huene in 1936 for cynodonts first found in São Pedro do Sul in Paleorrota, Brazil.

Procolophonia is an extinct clade of basal reptiles, traditionally classified as "parareptiles", that lived from the Middle Permian till the end of the Triassic period. The group includes the largest known parareptiles, the up to oxen-sized herbivorous pareiasaurs, as well as the longest lived "parareptiles", the small lizard-like procolophonoids. Although traditionally grouped in Parareptilia, this classification scheme has been questioned.

Ceratitida is an order that contains almost all ammonoid cephalopod genera from the Triassic as well as ancestral forms from the Upper Permian, the exception being the phylloceratids which gave rise to the great diversity of post-Triassic ammonites.

Eolacertilia ("dawn lizards") is an extinct clade of lepidosauriform diapsid reptiles known from the Late Permian to the Late Triassic. It is uncertain as to whether they are a natural group and it has been suggested that they form a "waste basket" taxon. Currently, the only members of the group are Paliguana and Kuehneosauridae. Other genera were transferred to basal groups within Diapsida (such as Palaeagama and Saurosternon), Archosauromorpha (Tanystropheus and Cteniogenys).

Diademodontidae is an extinct family of Triassic gomphodonts. The best-known genus is Diademodon from South Africa. Titanogomphodon from Namibia may also be a member of Diademodontidae. The Chinese genera Hazhenia and Ordosiodon have also been included in the family, but were more recently identified as baurioid therocephalians. Remains of a diademodontid were reported in the Early-Middle Triassic Fremouw Formation in Antarctica, but that specimen was later referred to the trirachodontid Impidens.

Metoposauroidea is an extinct superfamily of temnospondyls that lived from the Middle to Upper Triassic in North America, Europe and North Africa. Metoposauroidea includes the families Metoposauridae and Latiscopidae.

Toretocnemus (meaning 'perforated tibia') is an extinct genus of ichthyosaurs that lived during the Carnian stage of the Upper Triassic in what is now North America. Two species are known, T. californicus and T. zitelli, first described in 1903 by John Campbell Merriam from fossils discovered in the Hosselkus Limestone, Shasta County. The second species was first seen by Merriam as belonging to a distinct genus, but in 1999 it was reclassified into the original taxon. Toretocnemus fossils are primarily known from California, although some specimens are also reported from Alaska and Mexico. Wit

Gomphodontia is a clade of cynognathian cynodonts that includes the families Diademodontidae, Trirachodontidae, and Traversodontidae. Gomphodonts are distinguished by wide and closely spaced molar-like postcanine teeth, which are convergent with those of mammals. Other distinguishing characteristics of gomphodonts include deep zygomatic arches, upper postcanines with three or more cusps spanning their widths and lower postcanines with two cusps spanning their widths. They are thought to have been herbivorous or omnivorous. Gomphodonts first appeared in the Early Triassic and became extinct at

Chroniosuchia is a group of tetrapods that lived from the Middle Permian to Late Triassic in northern Pangaea in what is now Eurasia, including Laos, Kyrgyzstan, China, Germany and Russia. Chroniosuchians are often thought to be reptiliomorphs, but some recent phylogenetic analyses suggest instead that they are stem-tetrapods. They were all rather short limbed with a strong tail and elongated snout, somewhat resembling modern crocodiles. The group is traditionally considered to be a suborder or order of labyrinthodonts. Chroniosuchians likely had ecological niches as riverside predators, and m

Cynognathia ("dog jaw") is one of two major clades of cynodonts, the other being Probainognathia. Cynognathians included the large carnivorous genus Cynognathus and the herbivorous or omnivorous gomphodonts such as traversodontids. Cynognathians can be identified by several synapomorphies including a very deep zygomatic arch that extends above the middle of the orbit.

Doswelliidae is an extinct family of carnivorous archosauriform reptiles that lived in North America and Europe during the Middle to Late Triassic period. Long represented solely by the heavily-armored reptile Doswellia, the family's composition has expanded since 2011, although two supposed South American doswelliids (Archeopelta and Tarjadia) were later redescribed as erpetosuchids. Doswelliids were not true archosaurs, but they were close relatives and some studies have considered them among the most derived non-archosaurian archosauriforms. They may have also been related to the Proterocha

Gracilisuchidae is an extinct family of suchian archosaurs known from the early Middle Triassic to the early Late Triassic (Anisian – early Carnian) of China, Argentina, and Brazil.

Ankyramorpha ("anchor forms") is a proposed clade of early stem reptiles which lived between the early Cisuralian epoch (middle Sakmarian stage) and the latest Triassic period (latest Rhaetian stage) of Africa, Antarctica, Asia, Australia, Europe, North America and South America.

Ecteniniidae is an extinct family of probainognathian cynodonts from the Triassic of South America. They are notable for their large size, as well as for being among the first synapsids with specializations towards cursoriality.

Plagiosauroidea is a superfamily of stereospondyl temnospondyls that lived in the Triassic period.

Leptosuchomorpha is a clade of phytosaurs. It is a node-based taxon defined by Michelle R. Stocker in 2010 as the last common ancestor of Leptosuchus studeri and Pseudopalatus pristinus and all of its descendants. A new definition was proposed by Andrew S. Jones and Richard J. Butler in 2018 as the last common ancestor and all descendants of Smilosuchus lithodendrorum, Leptosuchus studeri, and Machaeroprosopus pristinus to reflect the new interrelationships of Phytosauria they recovered.

Chainosauria is a large and speciose clade of anomodont therapsid that includes the highly diverse dicynodonts and a small number of closely related basal genera (to the exclusion of Venyukovioidea and more basal anomodonts)—although the total composition and taxonomic scope of Chainosauria is in flux. Chainosauria was named in 1923 to group together the dicynodonts and their close relatives, namely three small anomodont genera from South Africa (Galechirus, Galeops, and Galepus) that made up the now defunct group 'Dromasauria'. The name soon fell into disuse, however, as it was functionally r

Dicynodontoidea is an infraorder of dicynodont therapsids that includes the famous dicynodont Dicynodon, Lystrosaurus and the Triassic Kannemeyeriiformes, as well as numerous other closely related species. The name was coined by American paleontologist Everett C. Olson in 1941 as an infraorder, despite using the typical "-oidea" suffix of superfamilies, and was later redefined under a phylogenetic context in 2009 by paleontologist Christian F. Kammerer.

Mystriosuchini, historically known as Pseudopalatinae, is an extinct tribe (formerly subfamily) of derived phytosaurs in the clade Leptosuchomorpha. As with all other phytosaurs, mystriosuchins lived during Late Triassic. The name is derived from the genus Mystriosuchus, and the clade was phylogenetically defined by Andrew S. Jones and Richard J. Butler in 2018 as the last common ancestor and all descendants of Mystriosuchus planirostris, Machaeroprosopus jablonskiae, and Machaeroprosopus buceros.

Heylerosauridae is a family of mastodonsauroid temnospondyls. It was first named in 1980 to include the genera Odenwaldia and Quasicyclotosaurus. In addition to these genera, the family now includes Eocyclotosaurus and Yuanansuchus. Recent phylogenetic analyses have not found a close relationship between Odenwaldia and other heylerosaurids and place it outside the family. Heylerosaurids are generally regarded as the sister taxon of the stenotosaurids.

Drepanosaurs (members of the clade Drepanosauromorpha) are a group of extinct reptiles that lived between the Carnian and Rhaetian stages of the late Triassic Period, approximately between 230 and 210 million years ago. The various species of drepanosaurs were characterized by a bird-like skull, a barrel-shaped body, and a horizontally narrow tail. A number of drepanosaurs had specialized grasping limbs and often prehensile tails similar to those of chameleons. Drepanosaurs are generally thought to have been arboreal (tree-dwelling), and probably insectivores. Some studies have alternately sug