Undorosaurus
Temporal range: Late Jurassic,[1]
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, 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), 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

Acamptonectes densus

Mollesaurus periallus

Ophthalmosaurus natans

Ophthalmosaurus icenicus

Gengasaurus nicosiai

Nannopterygius yasykovi

Nannopterygius enthekiodon

Nannopterygius saveljeviensis

Nannopterygius borealis

Arthropterygius volgensis

Arthropterygius lundi

Arthropterygius thalassonotus

Arthropterygius hoybergeti

Arthropterygius chrisorum

Platypterygiinae

Brachypterygius extremus

Aegirosaurus leptospondylus

Muiscasaurus catheti

Leninia stellans

Sveltonectes insolitus

Athabascasaurus bitumineus

Platypterygius americanus

Acuetzpalin carranzai

Platypterygius sachicarum

Caypullisaurus bonapartei

Grendelius mordax

Grendelius alekseevi

Grendelius pseudoscythicus

Grendelius zhuravlevi

Undorosaurus kielanae

Undorosaurus nessovi

Undorosaurus gorodischensis

Platypterygius australis

Plutoniosaurus bedengensis

Simbirskiasaurus birjukovi

Platypterygius hercynicus

Sisteronia seeleyi

Platypterygius platydactylus

Maiaspondylus lindoei

See also

References

  1. 1 2 "†Undorosaurus Efimov 1999". Paleobiology Database. Fossilworks. Retrieved 17 December 2021.
  2. 1 2 3 4 5 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. 1 2 3 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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