Undorosaurus

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Extinct genus of reptiles

title: "Undorosaurus" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["extinct-animals-of-russia", "late-jurassic-ichthyosaurs", "fossil-taxa-described-in-1999", "ophthalmosaurinae", "ichthyosauromorph-genera"] description: "Extinct genus of reptiles" topic_path: "geography/russia" source: "https://en.wikipedia.org/wiki/Undorosaurus" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Extinct genus of reptiles ::

| fossil_range = Late Jurassic, | image = Ундорозавр (Ихтиозавр (Ichthyopterygia)) Музей палеонтологии. Ундоры. Ульяновская обл. Ноябрь 2013 - panoramio.jpg | image_caption = Reconstructed skeleton of U. gorodischensis | taxon = Undorosaurus | authority = Efimov, 1999 | type_species = Undorosaurus gorodischensis | type_species_authority = (Efimov, 1999) | subdivision_ranks = Other species | subdivision = *U. nessovi Efimov, 1999

  • U. trautscholdi Arkhangelsky & Zverkov, 2014
  • U. kielanae Zverkov & Efimov, 2019 | synonyms = *Cryopterygius kielanae Tyborowski, 2016
  • Cryopterygius kristiansenae? Druckenmiller et al., 2012
  • Ophthalmosaurus gorodischensis Maisch & Matzke, 2000

Undorosaurus is an extinct genus of ophthalmosaurid ichthyosaur known from western Russia, Svalbard, and Poland. It was a large ichthyosaur, with the type species measuring 4 - long.

Discovery and naming

::figure[src="https://upload.wikimedia.org/wikipedia/commons/2/2d/Cryopterygius_skull_bones.jpg" caption="Skull bones of ''U. kielanae''"] ::

Undorosaurus was named by Vladimir M. Efimov in 1999 and the type species is Undorosaurus gorodischensis. The specific name is named after , the type locality of this taxon. 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.

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.

A second species, U. trautscholdi, was discovered in 1878 by Hermann Trautschold and was described by M.S. Arkhangelsky and N.G. Zverkov in 2014 from a partial left forefin found in the locality of , Moscow Oblast.

The holotype (specimen GMUL UŁ no. 3579-81) of the third species, U. kielanae, was discovered in the Kcynia Formation of the Owadów-Brzezinki Quarry, Poland, and it was first described by Daniel Tyborowski in 2016 as Cryopterygius kielanae. C. kielanae was moved to Undorosaurus by Zverkov & Efimov (2019).

Classification

::figure[src="https://upload.wikimedia.org/wikipedia/commons/0/06/Undorosaurus_kielanae_forefin.jpg" caption="Forefin of ''U. kielanae''"] ::

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

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.

Phylogeny

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

|label1=Ophthalmosauria |1={{clade |1={{clade |label1=Ophthalmosaurinae |1={{clade |1={{clade |1={{clade |1={{clade |1=Acamptonectes densus

|2={{clade |1=Mollesaurus periallus

|2={{clade |1=Ophthalmosaurus natans |2=Ophthalmosaurus icenicus |2={{clade |1={{clade |1=Gengasaurus nicosiai

|2={{clade |1={{clade |1=Nannopterygius yasykovi |2={{clade |1=Nannopterygius enthekiodon |2=Nannopterygius saveljeviensis |3=Nannopterygius borealis |2={{clade |1={{clade |1=Arthropterygius volgensis |2={{clade |1=Arthropterygius lundi |2=Arthropterygius thalassonotus |3={{clade |1=Arthropterygius hoybergeti |2=Arthropterygius chrisorum

|label2=Platypterygiinae |2={{clade |1={{clade |1=Brachypterygius extremus |2=Aegirosaurus leptospondylus

|3={{clade |1=Muiscasaurus catheti

|2={{clade |1=Leninia stellans

|2={{clade |1=Sveltonectes insolitus

|2={{clade |1=Athabascasaurus bitumineus

|2={{clade |1=Platypterygius americanus

|2={{clade |1={{clade |1=Acuetzpalin carranzai |2=Platypterygius sachicarum |3=Caypullisaurus bonapartei |2={{clade |1={{clade |1={{clade |1=Grendelius mordax |2=Grendelius alekseevi |3=Grendelius pseudoscythicus |4=Grendelius zhuravlevi |2={{clade |1={{clade |1={{clade |1=Undorosaurus kielanae |2={{clade |1=Undorosaurus nessovi |2=Undorosaurus gorodischensis |3={{clade |1=Platypterygius australis |2={{clade |1=Plutoniosaurus bedengensis |2=Simbirskiasaurus birjukovi |3=Platypterygius hercynicus |4=Sisteronia seeleyi |5=Platypterygius platydactylus |6=Maiaspondylus lindoei

Cryopterygius

::figure[src="https://upload.wikimedia.org/wikipedia/commons/b/b7/Undorosaurus_Skeleton.jpg" caption="[[Holotype]] of ''C. kristiansenae''"] ::

Cryopterygius (meaning 'frozen fin' in Greek) is a dubious extinct genus of ophthalmosaurid ichthyosaur known from the Agardhfjellet Formation of Norway. One species was recognised: C. kristiansenae.

The holotype, PMO 214.578, consists of a single, but largely complete specimen from the Slottsmøya Member of the Agardhfjellet Formation that was excavated between 2004 and 2012. Druckenmiller et al. (2012) subsequently named and described C. kristiansenae on the basis of this specimen. It has been suggested that C. kristiansenae may also be synonymous with Undorosaurus.

A second species, C. kielanae, was found in the Kcynia Formation from the Late Jurassic of Poland. It has since been synonymised with Undorosaurus and was found to be a species of Undorosaurus (U. kielanae).

References

References

  1. "†''Undorosaurus'' Efimov 1999". Fossilworks.
  2. M.S. Arkhangelsky. (2014). "On a new ichthyosaur of the genus ''Undorosaurus''". Proceedings of the Zoological Institute of the Russian Academy of Sciences.
  3. Daniel Tyborowski. (2016). "A new ophthalmosaurid ichthyosaur from the Late Jurassic of Owadów-Brzezinki Quarry, Poland". Acta Palaeontologica Polonica.
  4. 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.
  5. Trautschold, H. (1879). Uber eine Ichthyosaurus-Flosse aus dem Moskauer Kimmeridge. ''Zapisky Imperatorskogo Sankt-Peterburgskogo Mineralogicheskogo Obshestva''. Ser. 2, 14: 168–173
  6. Michael W. Maisch. (2000). "The Ichthyosauria". Stuttgarter Beiträge zur Naturkunde: Serie B.
  7. Storrs, Glenn W.. (2000). "The Age of Dinosaurs in Russia and Mongolia". Cambridge University Press.
  8. 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
  9. Michael W. Maisch. (2010). "Phylogeny, systematics, and origin of the Ichthyosauria – the state of the art". Palaeodiversity.
  10. Fischer, V.. (2011). "The first definite record of a Valanginian ichthyosaur and its implications on the evolution of post-Liassic Ichthyosauria". Cretaceous Research.
  11. Fischer, V.. (2011). "A new Barremian (Early Cretaceous) ichthyosaur from western Russia". Journal of Vertebrate Paleontology.
  12. (2019). "Revision of ''Undorosaurus'', a mysterious Late Jurassic ichthyosaur of the Boreal Realm". Journal of Systematic Palaeontology.
  13. (2021). "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.
  14. (2015-09-24}} [http://www.geologi.no/images/njg/2012/2-3/NJG_2_3_2012_17_Druckenmiller_etal_Pr.pdf High resolution pdf] {{webarchive). "Two new ophthalmosaurids (Reptilia: Ichthyosauria) from the Agardhfjellet Formation (Upper Jurassic: Volgian/Tithonian), Svalbard, Norway". Norwegian Journal of Geology.
  15. (2024-03-16). "A large new Middle Jurassic ichthyosaur shows the importance of body size evolution in the origin of the Ophthalmosauria". BMC Ecology and Evolution.
  16. Daniel Tyborowski. (2016). "A new ophthalmosaurid ichthyosaur from the Late Jurassic of Owadów-Brzezinki Quarry, Poland". Acta Palaeontologica Polonica.

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extinct-animals-of-russialate-jurassic-ichthyosaursfossil-taxa-described-in-1999ophthalmosaurinaeichthyosauromorph-genera