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Temporal range: Late Jurassic,[1] 150.8–145.5 Ma
Ундорозавр (Ихтиозавр (Ichthyopterygia)) Музей палеонтологии. Ундоры. Ульяновская обл. Ноябрь 2013 - panoramio.jpg
Recosntructed skeleton
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Ichthyosauria
Family: Ophthalmosauridae
Subfamily: Platypterygiinae
Genus: Undorosaurus
Efimov, 1999
  • U. gorodischensis Efimov, 1999[2]
  • U. trautscholdi Arkhangelsky & Zverkov, 2014[3]

Ophthalmosaurus gorodischensisMaisch & Matzke, 2000

Undorosaurus is an extinct genus of ophthalmosaurid ichthyosaur known from western Russia.[1][2][3]


Undorosaurus was first known from the holotype UPM EP-II-20 (527), a partial three-dimensionally preserved skeleton which preserved partial skull. It was collected near the Volga river at Gorodische from the Epivirgatites nikitini ammonoid zone, dating to the Late Jurassic.[2] A second species, U. trautscholdi was described by M.S. Arkhangelsky and N.G. Zverkov in 2014 from a partial left forefin found in the locality of Mnevniki, in the Moscow Oblast.[3]

Maisch and Matzke (2000) regarded Undorosaurus to be a species of Ophthalmosaurus.[4] However, Storrs et al. 2000 rejected this synonymy based on the tooth morphology of the specimen.[5] Chris McGowan and Ryosuke Motani (2003) pointed out two noteworthy differences to Ophthalmosaurus, an incompletely fused ischiopubis and a remarkably strong dentition, and considered Undorosaurus to be a valid genus of ophthalmosaurid.[6] Undorosaurus's validity is now accepted by most authors, even by Maisch (2010) who originally proposed the synonymy.[7][8][9]

Zverkov & Efimov (2019) considered the genus Cryopterygius to be a junior synonym of the genus Undorosaurus. The authors considered the type species of the former genus, C. kristiansenae, to be synonymous with Undorosaurus gorodischensis; second species of Cryopterygius, C. kielanae, was tentatively maintained by the authors as a distinct species within the genus Undorosaurus.[10]


Undorosaurus was named by Vladimir M. Efimov in 1999 and the type species is Undorosaurus gorodischensis. The specific name is named after Gorodische, the type locality of this taxon.[2] U. trautscholdi is named in honor of the geologist H. Trautschold who collected and made the first description of the fossils of the holotype of the species.[3]

See also[edit]


  1. ^ a b c "†Undorosaurus Efimov 1999". Paleobiology Database. Fossilworks. Retrieved 5 January 2016.
  2. ^ a b c d Vladimir M. Efimov (1999). "A new family of Ichthyosaurs, the Undorosauridae fam. nov. from the Volgian stage of the European part of Russia". Paleontological Journal. 33 (2): 174–181.CS1 maint: uses authors parameter (link)
  3. ^ a b c d M.S. Arkhangelsky and N.G. Zverkov (2014). "On a new ichthyosaur of the genus Undorosaurus" (PDF). Proceedings of the Zoological Institute of the Russian Academy of Sciences. 318 (3): 187–196.CS1 maint: uses authors parameter (link)
  4. ^ Michael W. Maisch and Andreas T. Matzke (2000). "The Ichthyosauria" (PDF). Stuttgarter Beiträge zur Naturkunde: Serie B. 298: 1–159.[permanent dead link]
  5. ^ Storrs, Glenn W.; Vladimir M. Efimov; Maxim S. Arkhangelsky (2000). "Mesozoic marine reptiles of Russia and other former Soviet republics". In Benton, M.J.; Shishkin, M.A.; and Unwin, D.M. (eds.). The Age of Dinosaurs in Russia and Mongolia. Cambridge: Cambridge University Press. pp. 140–159. ISBN 9780521545822.CS1 maint: uses editors parameter (link)
  6. ^ McGowan C, Motani R. 2003. Ichthyopterygia. – In: Sues, H.-D. (ed.): Handbook of Paleoherpetology, Part 8, Verlag Dr. Friedrich Pfeil, 175 pp., 101 figs., 19 plts; München
  7. ^ Michael W. Maisch (2010). "Phylogeny, systematics, and origin of the Ichthyosauria – the state of the art" (PDF). Palaeodiversity. 3: 151–214.CS1 maint: uses authors parameter (link)
  8. ^ Fischer, V.; A. Clement; M. Guiomar; P. Godefroit (2011). "The first definite record of a Valanginian ichthyosaur and its implications on the evolution of post-Liassic Ichthyosauria". Cretaceous Research. 32 (2): 155–163. doi:10.1016/j.cretres.2010.11.005.
  9. ^ Fischer, V.; Masure, E.; Arkhangelsky, M.S.; Godefroit, P. (2011). "A new Barremian (Early Cretaceous) ichthyosaur from western Russia". Journal of Vertebrate Paleontology. 31 (5): 1010–1025. doi:10.1080/02724634.2011.595464.
  10. ^ Nikolay G. Zverkov; Vladimir M. Efimov (2019). "Revision of Undorosaurus, a mysterious Late Jurassic ichthyosaur of the Boreal Realm". Journal of Systematic Palaeontology. 17 (14): 963–993. doi:10.1080/14772019.2018.1515793.