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Temporal range: Early Triassic
Tichvinskia vjatkensis.JPG
Tichvinskia vjatkensis
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Parareptilia
Order: Procolophonomorpha
Family: Procolophonidae
Genus: Tichvinskia
Ivakhnenko, 1973
Type species
Tichvinskia vjatkensis
Ivakhnenko, 1973

Tichvinskia is an extinct genus of procolophonid parareptile from the Early Triassic of Russia. [1]

A genus is a taxonomic rank used in the biological classification of living and fossil organisms, as well as viruses, in biology. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus.

Early Triassic first of three epochs of the Triassic period of the geologic timescale

The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between 251.902 Ma and 247.2 Ma. Rocks from this epoch are collectively known as the Lower Triassic, which is a unit in chronostratigraphy. The Early Triassic is the oldest epoch of the Mesozoic Era and is divided into the Induan and Olenekian ages.

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The Mesozoic Era is an interval of geological time from about 252 to 66 million years ago. It is also called the Age of Reptiles, a phrase introduced by the 19th century paleontologist Gideon Mantell who viewed it as dominated by diapsids such as Iguanodon, Megalosaurus, Plesiosaurus and Pterodactylus. To paleobotanists, this Era is also called the Age of Conifers.

Permian–Triassic extinction event most severe extinction event of Earths chronology, occurring approx 252 million years ago, ending the Paleozoic era (and the Permian period) and beginning the Mesozoic era (and the Triassic period)

The Permian–Triassicextinction event, colloquially known as the Great Dying, the End-Permian Extinction or the Great Permian Extinction, occurred about 252 Ma ago, forming the boundary between the Permian and Triassic geologic periods, as well as between the Paleozoic and Mesozoic eras. It is the Earth's most severe known extinction event, with up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct. It is the only known mass extinction of insects. Some 57% of all biological families and 83% of all genera became extinct. Because so much biodiversity was lost, the recovery of land-dwelling life took significantly longer than after any other extinction event, possibly up to 10 million years. Studies in Bear Lake County, near Paris, Idaho, showed a relatively quick rebound in a localized marine ecosystem, taking around 2 million years to recover, suggesting that the impact of the extinction may have been felt less severely in some areas than others.

The Triassic is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.9 million years ago (Mya), to the beginning of the Jurassic Period 201.3 Mya. The Triassic is the first period of the Mesozoic Era. Both the start and end of the period are marked by major extinction events.

Therapsid Order of tetrapods (fossil)

Therapsida is a group of synapsids that includes mammals and their ancestors. Many of the traits today seen as unique to mammals had their origin within early therapsids, including having their four limbs extend vertically beneath the body, as opposed to the sprawling posture of reptiles. The earliest fossil attributed to Therapsida is Tetraceratops insignis from the Lower Permian.

Herrerasauridae family of dinosaurs, among the oldest known dinosaurs, Triassic period (fossil)

Herrerasauridae is a family of carnivorous basal saurischian dinosaurs. They are among the oldest known dinosaurs, first appearing in the fossil record around 233.23 million years ago, before becoming extinct by the end of the Triassic period. Herrerasaurids were relatively small-sized dinosaurs, normally not more than 4 metres (13 ft) long. The best known representatives of this group are from South America, where they were first discovered in the 1960s. A nearly complete skeleton of Herrerasaurus ischigulastensis was discovered in the Ischigualasto Formation in San Juan, Argentina, in 1988. Less complete herrerasaurids have been found in North America, and they may have inhabited other continents as well.

Early Jurassic

The Early Jurassic epoch is the earliest of three epochs of the Jurassic period. The Early Jurassic starts immediately after the Triassic-Jurassic extinction event, 201.3 Ma, and ends at the start of the Middle Jurassic 174.1 Ma.

<i>Lystrosaurus</i> Genus of Late Permian and Early Triassic dicynodont therapsids

Lystrosaurus was a herbivorous genus of Late Permian and Early Triassic Period dicynodont therapsids, which lived around 250 million years ago in what is now Antarctica, India, and South Africa. Four to six species are currently recognized, although from the 1930s to 1970s the number of species was thought to be much higher. They ranged in size from a small dog to 2.5 meters long.

The Late Triassic is the third and final of three epochs of the Triassic Period in the geologic timescale. The Triassic-Jurassic extinction event began during this epoch and is one of the five major mass extinction events of the Earth. The corresponding series is known as the Upper Triassic. In Europe the epoch was called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age. The Late Triassic spans the time between 237 Ma and 201.3 Ma. The Late Triassic is divided into the Carnian, Norian and Rhaetian ages.

<i>Arizonasaurus</i> genus of reptiles

Arizonasaurus was a ctenosauriscid archosaur from the Middle Triassic. Arizonasaurus is found in the Middle Triassic Moenkopi Formation of northern Arizona. A fairly complete skeleton was found in 2002 by Sterling Nesbitt. The taxon has a large sailback formed by elongated neural spines of the vertebrae. The type species, Arizonasaurus babbitti, was named by Samuel Paul Welles in 1947.

Technosaurus is an extinct genus of Late Triassic dinosauriform, from the Late Triassic Bull Canyon Formation of Texas, United States.

Therocephalia suborder of mammals (fossil)

Therocephalia is an extinct suborder of eutheriodont therapsids from the Permian and Triassic. The therocephalians ("beast-heads") are named after their large skulls, which, along with the structure of their teeth, suggest that they were carnivores. Like other non-mammalian synapsids, therocephalians were once described as "mammal-like reptiles". Therocephalia is the group most closely related to the cynodonts, which gave rise to the mammals. This relationship takes evidence in a variety of skeletal features. The phylogeny of therocephalians has been disputed, as the monophyly of the group and the relationships of its members are unclear.

Theriodont taxon of mammals (fossil)

The theriodonts or Theriodontia are a major group of therapsids. They can be defined in traditional, Linnaean terms, in which case they are a suborder of synapsids that lived from the Middle Permian to the Middle Cretaceous, or in cladistic terms, in which case they include not only the traditional theriodonts but also their descendants the mammals as well.

Rauisuchidae family of reptiles

Rauisuchidae is a group of large predatory Triassic archosaurs. There is some disagreement over which genera should be included in Rauisuchidae and which should be in the related Prestosuchidae and Poposauridae, and indeed whether these should even be thought of as separate families. Rauisuchids occurred throughout much of the Triassic, and may have first occurred in the Early Triassic if some archosaurian taxa such as Scythosuchus and Tsylmosuchus are considered to be within the family.

Dinosauromorpha clade of reptiles (fossil)

Dinosauromorpha is a clade of archosaurs that includes the clade Dinosauria (dinosaurs), and all animals more closely related to dinosaurs than to pterosaurs. Birds are the only surviving dinosauromorphs.

Stereospondyli suborder of amphibians (fossil)

The Stereospondyli are a group of extinct temnospondyl amphibians. Relative to other early tetrapods (labyrinthodonts), they had simplified backbones, where the whole vertebra was made of a single intercentrum, topped by a neural arch. The whole vertebral structure was rather weak, meaning that most stereospondyls were aquatic. The family Plagiosauridae appear to have been wholly aquatic and retained their larval gills in adulthood.

Procolophonidae family of reptiles

Procolophonidae is an extinct family of parareptiles from the Permian and Triassic periods.

Guaibasauridae family of reptiles (fossil)

Guaibasauridae is a family of basal saurischian dinosaurs, known from fossil remains of late Triassic period formations in Brazil and Argentina.

Gracilisuchidae is an extinct family of suchian archosaurs known from the early Middle Triassic to the early Late Triassic of China and Argentina.


Dracohors is a clade of dinosauriform archosaurs that includes dinosaurs and silesaurids. The oldest known dracohorsian is Asilisaurus, dating to about 245 million years ago in the Anisian age of the middle Triassic period. According to Andrea Cau (2018), the synapomorphies of dracohorsians are:

The anterior tympanic recess, the axial epipophyses, the centrodiapophyseal laminae in the presacral vertebrae, the relative size enlargement of the postacetabular process of ilium, the elongation of the pubis, the proximal sulcus and the reduction of the ligament tuber in the femoral head, and the further reduction in length of the fourth metatarsal and toe compared to the third.


  1. Ivakhnenko, M.F. (1973). "Skull structure in the Early Triassic procolophonian Tichvinskia vjatkensi". Paleontological Journal. 4: 74–83.