Simbirskiasaurus
Temporal range: Early Cretaceous, 130 Ma
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Ichthyosauria
Family: Ophthalmosauridae
Subfamily: Platypterygiinae
Genus: Simbirskiasaurus
Ochev and Efimov, 1985
Species
  • S. birjukovi Ochev and Efimov, 1985 (Type)

Simbirskiasaurus is an extinct genus of ichthyosaur from the Early Cretaceous (early Barremian) of Ulyanovsk Oblast, Russia.[1][2] Its type specimen is YKM 65119, a fragmentary skull and vertebral column.[3]

Description

Fischer et al. give the diagnosis of Simbirskiasaurus as follows: "Platypterygiine ophthalmosaurid characterized by the following autapomorphies: external naris divided by a nasomaxillary pillar; posterior opening of the narial complex with anteroposteriorly constricted dorsal extension; deeply interdigitating prefrontal–lacrimal suture [reminiscent of the basal neoichthyosaurian Temnodontosaurus platyodon (Conybeare, 1822); see Godefroit, 1993]. Simbirskiasaurus birjukovi is also characterized by the following unique combination of features: subnarial process of the premaxilla reaches the posterior margin of the external naris (shared with Cryopterygius kristiansenae Druckenmiller et al., 2012); elongated anterior process of the maxilla, reaching anteriorly the level of the nasal [unlike in Aegirosaurus leptospondylus Bardet & Fernández, 2000 and Sveltonectes insolitus (Fischer et al., 2011b)]; pres- ence of a supranarial process of the premaxilla [shared with Platypterygius australis (McCoy, 1867), see Kear, 2005, and possibly Pervushovisaurus bannovkensis (Arkhangelsky, 1998b)]."[2]

Phylogeny

The following cladogram shows a possible phylogenetic position of Simbirskiasaurus in Ophthalmosauridae according to the analysis performed by Zverkov and Jacobs (2020).[4]

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. Sepkoski, Jack (2002). "A compendium of fossil marine animal genera (entry on Reptilia)". Bulletins of American Paleontology. 364: 560. Retrieved 2008-09-28.
  2. 1 2 Valentin Fischer, Maxim S. Arkhangelsky, Darren Naish, Ilya M. Stenshin, Gleb N. Uspensky and Pascal Godefroit (2014) Simbirskiasaurus and Pervushovisaurus reassessed: implications for the taxonomy and cranial osteology of Cretaceous platypterygiine ichthyosaurs. Zoological Journal of the Linnean Society 171(4): 822–841. http://onlinelibrary.wiley.com/doi/10.1111/zoj.12158/abstract
  3. Storrs, G. W., M. S. Arkhangel'skii and V. M. Efimov. 2000. Mesozoic marine reptiles of Russia and other former Soviet republics. pages 187-210 In Benton, M. J., M. A. Shiskin, D. M. Unwin and E. N. Kurochkin, (eds.), The Age of Dinosaurs in Russia and Mongolia, Cambridge University Press, Cambridge.
  4. 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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