This article is about the therapsid genus. For the group of animals, see Dinosaur. For the film, see Dinosaurus! For the temnospondyl amphibian, see Dvinosaurus.
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 PermianofRussia. 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.
The holotype of Dinosaurus murchisonii was collected in a copper mine in the Orenburg Governorate of the Russian Empire during the 1840s.[2] 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.[3] 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.[4]
In 1894, H. G. Seeley remarked that Cliorhizodon, which is now regarded as a junior synonym of Syodon,[5] could not be distinguished from Dinosaurus.[6] In 1954, Ivan Efremov synonymized Dinosaurus with Brithopus. This has been followed by some other authors,[7] 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.[8] As such, he classified Dinosaurus in the family Phthinosuchidae, which he grouped with Rubidgeidae[a] in the superfamily Rubidgeoidea of the order Gorgonopia.[10] Kammerer has remarked that the limited anatomical information available for Dinosaurus makes it hard to confirm this proposed synonymy.[11]
Battail, Bernard; Surkov, Mikhail V. (2003-12-04). "Mammal-like reptiles from Russia". In Benton, Michael J.; Shishkin, Mikhail A.; Unwin, David M.; Kurochkin, Evgenii N. (eds.). The Age of Dinosaurs in Russia and Mongolia. Cambridge University Press. ISBN978-0-521-54582-2.
Baur, G.; Case, E. C. (1899). "The history of the Pelycosauria, with a description of the genus Dimetrodon, Cope". Transactions of the American Philosophical Society. 20.
Eichwald, Eduard (1848), Ueber die Saurier des Kupferführenden Zechsteins Russlands, Moscow
Ivakhnenko, M. F. (2000).『Зстемменозухи и примитивные териодонты позлней перми』[Estemmenosuches and primitive theriodonts from the Late Permian]. Paleontologicheskii Zhurnal (in Russian) (2): 72–80.
Ivakhnenko, M. F. (2002).『Систематика восточноевропейских горгонопий (Therapsida)』[Taxonomy of East European Gorgonopia (Therapsida)]. Paleontologicheskii Zhurnal (in Russian) (3): 56–65.
