''Phaanthosaurus'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of basal

procolophonid Procolophonidae is an extinct family of small, lizard-like 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, Antarc ...

parareptile Parareptilia ("at the side of reptiles") is a subclass or clade of basal sauropsids (reptiles), typically considered the sister taxon to Eureptilia (the group that likely contains all living reptiles and birds). Parareptiles first arose near the ...

from early

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...

(

Induan The Induan is the first age of the Early Triassic epoch in the geologic timescale, or the lowest stage of the Lower Triassic series in chronostratigraphy. It spans the time between 251.902 Ma and Ma (million years ago). The Induan is sometimes ...

stage) deposits of

Nizhnii Novgorod Nizhny Novgorod ( ; rus, links=no, Нижний Новгород, a=Ru-Nizhny Novgorod.ogg, p=ˈnʲiʐnʲɪj ˈnovɡərət ), colloquially shortened to Nizhny, from the 13th to the 17th century Novgorod of the Lower Land, formerly known as Gork ...

Russian Federation Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

. It is known from the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

PIN A pin is a device used for fastening objects or material together. Pin or PIN may also refer to: Computers and technology * Personal identification number (PIN), to access a secured system ** PIN pad, a PIN entry device * PIN, a former Dutch de ...

1025/1, a

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...

(a dentary). It was collected from Vetluga River, Spasskoe village and referred to the Vokhmian terrestrial horizon of the

Vokhma Formation Vokhma (russian: Во́хма) is a rural locality (a ''settlement'') and the administrative center of Vokhomsky District, Kostroma Oblast, Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transco ...

. It was first named by P. K. Chudinov and B. P. Vjushkov in

1956 Events January * January 1 – The Anglo-Egyptian Sudan, Anglo-Egyptian Condominium ends in Sudan. * January 8 – Operation Auca: Five U.S. evangelical Christian Missionary, missionaries, Nate Saint, Roger Youderian, Ed McCully, Jim ...

and the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

is ''Phaanthosaurus ignatjevi''. In 2000, Spencer and Benton found ''Contritosaurus'' to be

junior synonym The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently. * In botanical nomenclature, a synonym is a scientific name that applies to a taxon that (now) goes by a different scientific name. For example, Linna ...

of ''Phaanthosaurus''. ''C. simus'' Ivakhnenko, 1974 which is known from the

3355/1, a partial

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...

with right

from the same location, and from three paratypes, was recombined as ''P. simus''. They also found that the second species of ''Contritosaurus'', ''C. convector'' (PIN 3357/1, a mandible) is a

of ''P. simus''. Recent

cladistic Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups (" clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived char ...

analyses by Juan Carlos Cisneros, 2008 and Mark J. Macdougall and Sean P. Modesto, 2011 accepted this synonymy.

References

Procolophonids Early Triassic reptiles of Asia Fossil taxa described in 1956 Prehistoric reptile genera {{triassic-reptile-stub