''Dinosaurus'' is an extinct genus of

therapsid Therapsida is a major group of eupelycosaurian synapsids that includes mammals, their ancestors and relatives. Many of the traits today seen as unique to mammals had their origin within early therapsids, including limbs that were oriented more ...

of controversial affinities. Its type and only species is ''Dinosaurus murchisonii''. It is only known from a partial snout from the

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...

Russia 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 ...

. Its taxonomic history is intertwined with several other poorly-known Russian therapsids, particularly ''

Rhopalodon ''Rhopalodon'' is an extinct genus of therapsids from the Permian of Russia. It has been variously classified as a dinosaur, a dinocephalian, or another branch of Reptilia. ''Rhopalodon'' is notable for being among the first reptiles mentioned in ...

'', ''

Brithopus ''Brithopus'' is an extinct genus of dinocephalian therapsids. It contains a single species, ''Brithopus priscus'', known from fragmentary remains found in the Copper Sandstones near Isheevo, Russia. Description ''Brithopus'' was fairly large, ...

'', and ''

Phthinosuchus ''Phthinosuchus'' is an extinct genus of therapsids from the Middle Permian of Russia. ''Phthinosuchus'' is the sole member of the family Phthinosuchidae. ''Phthinosuchus'' may have been one of the most primitive therapsids, meaning that its ance ...

''. ''Dinosaurus'' is not a

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

; the similarity in names is coincidental. Dinosaurs are reptiles, whereas ''Dinosaurus'' is a therapsid, and as such, more closely related to

mammals Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

. Dinosauria was named only five years prior to ''Dinosaurus'', in 1842.

History of study

The holotype of ''Dinosaurus murchisonii'' was collected in a copper mine in the

Orenburg Governorate Orenburg Governorate (russian: Оренбургская губерния) was an administrative division (a '' guberniya'') of the Russian Empire with the center in the city of Orenburg, Ufa (1802-1865). The governorate was created in 1744 from ...

of the

Russian Empire The Russian Empire was an empire and the final period of the Russian monarchy from 1721 to 1917, ruling across large parts of Eurasia. It succeeded the Tsardom of Russia following the Treaty of Nystad, which ended the Great Northern War. ...

during the 1840s. It was collected in two pieces, found on separate occasions. The director of the mine, Wagenheim von Qualen, initially identified the first piece as a plant fossil in a letter to Johann Fischer von Waldheim, but Fischer realized it was part of a skull and described it as a new species of ''Rhopalodon'', ''R. murchisonii'', in 1845. In 1847, Fischer described the second piece and established a new genus, ''Dinosaurus'', for the species. In 1848, Eichwald recognized that the two specimens were not only from the same species, but fit together as parts of the same individual. He provisionally returned the species to ''Rhopalodon'', as he felt there were not enough differences yet identified to justify a second genus, and noted the existence of the similarly-named taxon Dinosauria, named by

Richard Owen Sir Richard Owen (20 July 1804 – 18 December 1892) was an English biologist, comparative anatomist and paleontologist. Owen is generally considered to have been an outstanding naturalist with a remarkable gift for interpreting fossils. Owe ...

only a few years prior, in 1842. Wagenheim von Qualen donated both specimens to the collection of Maximilian de Beuharnais,

Duke of Leuchtenberg Duke of Leuchtenberg was a title created twice by List of rulers of Bavaria, the monarchs of Bavaria for their relatives. The first creation was awarded by Maximilian I, Elector of Bavaria to his son Maximilian Philipp Hieronymus, upon whose death ...

, and the originals have since been lost. However, casts of the specimens are housed in the

Paleontological Institute, Russian Academy of Sciences The Paleontological Institute, Russian Academy of Sciences (PIN; russian: Палеонтологический институт РАН) in Moscow is among the world's largest paleontological institutes. An affiliate of the Russian Academy of Scienc ...

under the catalog numbers PIN 296/1 and PIN 296/2. In 1894, H. G. Seeley remarked that ''Cliorhizodon'', which is now regarded as a junior synonym of ''

Syodon ''Syodon'' is an extinct genus of dinocephalian therapsids that lived approximately 267-260 million years ago during the middle Permian period of the Paleozoic era. These therapsids, located in Russia were initially believed to be true mammals. ...

'', could not be distinguished from ''Dinosaurus''. In 1954, Ivan Efremov synonymized ''Dinosaurus'' with ''

''. This has been followed by some other authors, but Christian Kammerer has regarded ''Brithopus'', which is based on only a partial humerus, as a ''

nomen dubium In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium'' it may be impossible to determine whether a s ...

'', and as such did not regard ''Dinosaurus'' as synonymous with it. In 2000, M. F. Ivakhnenko synonymized ''

'' with ''Dinosaurus''. As such, he classified ''Dinosaurus'' in the family Phthinosuchidae, which he grouped with Rubidgeidae in the superfamily Rubidgeoidea of the order Gorgonopia. Kammerer has remarked that the limited anatomical information available for ''Dinosaurus'' makes it hard to confirm this proposed synonymy.

Footnotes

References

Works cited

* * * * * * * * {{Taxonbar, from=Q109233711 Monotypic prehistoric animal genera Fossils of Russia Fossil taxa described in 1845

History of study

See also

Footnotes

References

Works cited