| Dinosaurus | |
|---|---|
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Synapsida |
| Clade: | Therapsida |
| Genus: | †Dinosaurus Fischer, 1847 |
| Species: | †D. murchisonii |
| Binomial name | |
| †Dinosaurus murchisonii (Fischer, 1845) | |
Dinosaurus is an extinct genus oftherapsid of controversial affinities. Its type and only species isDinosaurus murchisonii. It is only known from a partial snout from thePermian ofRussia. Its taxonomic history is intertwined with several other poorly-known Russian therapsids, particularlyRhopalodon,Brithopus, andPhthinosuchus.
Dinosaurus is not adinosaur; the similarity in names is coincidental. Dinosaurs belong to the clade Dinosauria, a clade of reptiles, whereasDinosaurus is a therapsid, and as such, more closely related tomammals. Dinosauria was named only five years prior toDinosaurus, in 1842.Dinosaurus also lived in the Permian period, which is part of thePaleozoic era, before dinosaurs existed, the first dinosaurs appeared in the followingTriassic period of theMesozoic era.
The holotype ofDinosaurus murchisonii was collected in a copper mine in theOrenburg Governorate of theRussian 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 ofRhopalodon,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 toRhopalodon, as he felt there were not enough differences yet identified to justify a second genus, and noted the existence of the similarly-named taxonDinosauria, named byRichard Owen only a few years prior, in 1842.[4]
Wagenheim von Qualen donated both specimens to the collection ofMaximilian de Beuharnais,Duke of Leuchtenberg, and the originals have since been lost. However, casts of the specimens are housed in thePaleontological Institute, Russian Academy of Sciences under the catalog numbers PIN 296/1 and PIN 296/2.
In 1894,H. G. Seeley remarked thatCliorhizodon, which is now regarded as a junior synonym ofSyodon,[5] could not be distinguished fromDinosaurus.[6] In 1954,Ivan Efremov synonymizedDinosaurus withBrithopus. This has been followed by some other authors,[7] but Christian Kammerer has regardedBrithopus, which is based on only a partial humerus, as anomen dubium, and as such did not regardDinosaurus as synonymous with it.
In 2000, M. F. Ivakhnenko synonymizedPhthinosuchus withDinosaurus.[8] As such, he classifiedDinosaurus in the family Phthinosuchidae, which he grouped withRubidgeidae[a] in the superfamily Rubidgeoidea of the order Gorgonopia.[10] Kammerer has remarked that the limited anatomical information available forDinosaurus makes it hard to confirm this proposed synonymy.[11]