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Undorosaurus
Temporal range: Late Jurassic, [1] 150.8–145.5  Ma
Recosntructed skeleton
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: † Ichthyosauria
Family: † Ophthalmosauridae
Subfamily: † Platypterygiinae
Genus: † Undorosaurus
Efimov, 1999
Type species
†Undorosaurus gorodischensis
(Efimov, 1999)
Other species
  • †U. nessovi Efimov, 1999
  • †U. trautscholdi Arkhangelsky & Zverkov, 2014 [2]
  • †U. kielanae Tyborowski, 2016 [3]
Synonyms

Undorosaurus is an extinct genus of ophthalmosaurid ichthyosaur known from western Russia, Svalbard, and Poland. [1] [4] [2] It was a large ichthyosaur, with the type species measuring 4–6 metres (13–20 ft) long. [2]

Discovery and naming

Undorosaurus was named by Vladimir M. Efimov in 1999 and the type species is Undorosaurus gorodischensis. The specific name is named after Gorodischi [ ru], the type locality of this taxon. [4] U. trautscholdi is named in honor of the geologist Hermann Trautschold who collected and made the first description of the fossils of the holotype of the species. [2]

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 Gorodischi from the Epivirgatites nikitini ammonoid zone, dating to the Late Jurassic. [4] 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 Mnyovniki (Mnevniki) [ ru], Moscow Oblast. [2]

Classification

Maisch and Matzke (2000) regarded Undorosaurus to be a species of Ophthalmosaurus. [5] However, Storrs et al. 2000 rejected this synonymy based on the tooth morphology of the specimen. [6] 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. [7] Undorosaurus's validity is now accepted by most authors, even by Maisch (2010) who originally proposed the synonymy. [8] [9] [10]

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. [11]

Phylogeny

The following cladogram shows a possible phylogenetic position of Undorosaurus in Ophthalmosauridae according to the analysis performed by Zverkov and Jacobs (2020). [12]

Ophthalmosauria
Ophthalmosaurinae
Platypterygiinae

See also

References

  1. ^ a b "†Undorosaurus Efimov 1999". Paleobiology Database. Fossilworks. Retrieved 17 December 2021.
  2. ^ a b c d e M.S. Arkhangelsky & 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.
  3. ^ Daniel Tyborowski (2016). "A new ophthalmosaurid ichthyosaur from the Late Jurassic of Owadów-Brzezinki Quarry, Poland". Acta Palaeontologica Polonica. 61 (4): 791–803. doi: 10.4202/app.00252.2016.
  4. ^ a b c 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.
  5. ^ Michael W. Maisch & Andreas T. Matzke (2000). "The Ichthyosauria". Stuttgarter Beiträge zur Naturkunde: Serie B. 298: 1–159.
  6. ^ 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. & Unwin, D.M. (eds.). The Age of Dinosaurs in Russia and Mongolia. Cambridge: Cambridge University Press. pp. 140–159. ISBN  9780521545822.
  7. ^ 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
  8. ^ Michael W. Maisch (2010). "Phylogeny, systematics, and origin of the Ichthyosauria – the state of the art" (PDF). Palaeodiversity. 3: 151–214.
  9. ^ 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. hdl: 2268/79923. S2CID  45794618.
  10. ^ 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. hdl: 2268/92828. S2CID  86036325.
  11. ^ 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. S2CID  91912834.
  12. ^ Nikolay G. Zverkov & Megan L. Jacobs (2021) [2020]. "Revision of Nannopterygius (Ichthyosauria: Ophthalmosauridae): reappraisal of the 'inaccessible' holotype resolves a taxonomic tangle and reveals an obscure ophthalmosaurid lineage with a wide distribution". Zoological Journal of the Linnean Society. 191 (1): 228–275. doi: 10.1093/zoolinnean/zlaa028.
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