Dinosaurus

''Dinosaurus'' is an extinct genus of therapsid of controversial affinities. Its type and only species is ''Dinosaurus murchisonii''. It is only known from a partial snout from the Permian of Russia. Its taxonomic history is intertwined with several other poorly-known Russian therapsids, particularly '' Rhopalodon'', '' Brithopus'', and ''Phthinosuchus''.

''Dinosaurus'' is not a dinosaur; the similarity in names is coincidental. Dinosaurs belong to the clade Dinosauria, a clade of reptiles, whereas ''Dinosaurus'' is a therapsid, and as such, more closely related to mammals. Dinosauria was named only five years prior to ''Dinosaurus'', in 1842. ''Dinosaurus'' also lived in the Permian period, which is part of the Paleozoic era, before dinosaurs existed, the first dinosaurs appeared in the following Triassic period of the Mesozoic era.

History of study

The holotype of ''Dinosaurus murchisonii'' was collected in a copper mine in the Orenburg Governorate of the Russian Empire 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 only a few years prior, in 1842.

Wagenheim von Qualen donated both specimens to the collection of Maximilian de Beuharnais, Duke of Leuchtenberg, and the originals have since been lost. However, casts of the specimens are housed in the Paleontological Institute, Russian Academy of Sciences 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'', could not be distinguished from ''Dinosaurus''. In 1954, Ivan Efremov synonymized ''Dinosaurus'' with '' Brithopus''. 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'', and as such did not regard ''Dinosaurus'' as synonymous with it.

In 2000, M. F. Ivakhnenko synonymized ''Phthinosuchus'' 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.

See also

* ''Gresslyosaurus'' – Originally was to be called "Dinosaurus"

Footnotes

References

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{{Taxonbar, from=Q109233711

Monotypic prehistoric animal genera
Fossils of Russia
Fossil taxa described in 1845