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Platypterygius

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Platypterygius is a historically paraphyletic genus of platypterygiine ichthyosaur from the Cretaceous period. It was historically used as a wastebasket taxon, and most species within Platypterygius likely are undiagnostic at the genus or species level, or represent distinct genera, even being argued as invalid.[2] While fossils referred to Platypterygius have been found throughout different continents, the holotype specimen was found in Germany.

Platypterygius
Temporal range: Late Aptian-Late Cenomanian
113–93.9 Ma
Assigned P. australis specimen
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: †Ichthyosauria
Family: †Ophthalmosauridae
Subfamily: †Platypterygiinae
Genus: †Platypterygius
von Huene, 1922
Type species
†Platypterygius platydactylus
(Broili, 1907)
Other species
  • †P. americanus
    (Nace, 1939)
  • †P. australis
    (McCoy, 1867)
  • †P. hercynicus
    Kuhn, 1946
  • †P. elsuntuoso
    Fonseca, Cabra, & Camacho, 2024
Synonyms
  • Ichthyosaurus platydactylus
    Broili, 1907
  • Longirostria australis
    McCoy, 1867
  • Myobradypterygius mollensis
    Rusconi, 1938[1]
  • Platypterygius longmani
    Wade, 1990
  • Tenuirostria americanus
    Hace, 1939

Description

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Restoration of P. australis

As Platypterygius contains multiple species not especially close to each other, little can be said in terms of shared characteristics. According to an analysis by Fischer (2012), all anatomical features used to unify Platypterygius species are either not actually present in each species, or much more widespread among unrelated ophthalmosaurs. Generally, species referred to this genus were large bodied macropredators based on their robust dentition.[3] This is also supported by P. australis having been found with remains of sea turtles and birds (specifically, of the genus Nanantius) in its guts,[4] as well as an unidentified pterosaur fossil with tooth marks that may be from this genus.

In 1998, Arkhangelsky estimated that P. platydactylus was about 5 metres (16 ft) long, while "P." americanus was about 5.5 metres (18 ft) long.[5] In 2010, Zammit and colleagues estimated that "P." australis was about 7 metres (23 ft) long.[6]

Discovery and species

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Skull of P. sp., Sternberg Museum of Natural History

The type species of Platypterygius was described in 1922 based on remains found in upper Aptian strata around Hannover, Germany that were previously described as a species of Ichthyosaurus (I. platydactylus) in 1907 by Ferdinand Broili. These remains however were not adequately described and to complicate matters further, destroyed during World War 2. In the time after its discovery however Platypterygius has become a catch-all genus for Cretaceous ichthyosaurs, creating the misconstrued view of post-Jurassic ichthyosaurs as being a single global genus lacking in diversity. Later research conducted in the 2000s and 2010s has repeatedly shown this to be false, with all of the autapomorphies previously used to define Platypterygius either not being present in all assigned species or also being present in other ophthalmosaurids.[7] As the holotype was destroyed, a redescription of the material attempting to identify valid autapomorphies is out of the question and leaves the genus in a problematic state. Furthermore, the inclusion of later described genera of Cretaceous, platypterygiine ichthyosaurs has shown Platypterygius to be paraphyletic, with the different species not clading closely to one another. Subsequently, many redescriptions of referred Platypterygius species have found them to be their own distinct genera.

One notable attempt at revising Platypterygius was conducted by Arkhangel'sky in 1998, who split the genus into three new subgenera. Longirostria (including the Australian "P." longmani, a synonym of "P." australis, and the Argentinian "P." hauthali), Tenuirostria ("P." americanus) and Pervushovisaurus (which included the newly described "P." bannovkensis). Both Platypterygius platydactylus,"P." kiprianoffi and "P." hercynicus were placed in the subgenus Platypterygius.[5]

"Platypterygius" bannovkensis was eventually elevated to its own genus Pervushovisaurus in 2014, utilizing Arkhangel'sky's proposed subgenus name[8] and "P." campylodon was also assigned to this genus by a study published in 2016.[9] "P." kiprianoffi was also assigned to P. campylodon (now Pervushovisaurus).[10][11][12] Simbirskiasaurus was originally described in 1985 and later sunk into Platypterygius before being declared distinct in the same paper as Pervushovisaurus.[8] "Platypterygius" ochevi, described in 2008 by Arkhangel'sky et al., was found to be a junior synonym of Maiaspondylus cantabrigiensis[13] and in 2021 "Platypterygius" sachicarum was described by Cortés et al. as Kyhytysuka sachicarum.[14] It is argued that the inclusion of oldest species "P." hauthali requires reinvestigation,[12] for it lacks a skull to attribute.[15] Because of this, recent analyses on ichthyosaur classification neglect this species.[16][17] In 2024, "P." hauthali was reclassified back into the original genus, Myobradypterygius.[18]

Accepted species

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Opalized vertebral column assigned to an immature P. cf. longmani (a synonym of P. australis)
  • Platypterygius platydactylus Broilli, 1907 (type)
  • Platypterygius americanus Nace, 1939 (=Tenuirostria)
  • Platypterygius australis McCoy, 1867 (=Longirostria)
  • Platypterygius hercynicus Kuhn, 1946

Formerly assigned species

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Classification

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Skeleton of P. australis in Museum and Art Gallery of the Northern Territory

The following cladogram shows the internal relationships of ophthalmosaurian ichthyosaurs according to an analysis performed by Zverkov and Jacobs (2020) which shows that P. americanus is too distantly related compared to the other three species.[17]

Ophthalmosauria
Ophthalmosaurinae
Platypterygiinae

See also

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References

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  1. ^ C. Rusconi. (1938). Restos de ictiosaurios del Jurásico Superior de Mendoza [Remains of ichthyosaurs from the Upper Jurassic of Mendoza]. Boletin Paleontológico de Buenos Aires 10:1-4
  2. ^ 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. Bibcode:2011JVPal..31.1010F. doi:10.1080/02724634.2011.595464. hdl:2268/92828. S2CID 86036325.
  3. ^ Fischer, V.; Bardet, N.; Benson, R.B.J.; Arkhangelsky, M.S.; Friedman, M. (2016). "Extinction of Fish-shaped Marine Reptiles Associated with Reduced Evolutionary Rates and Global Environmental Volatility". Nature Communications. 7: 10825. Bibcode:2016NatCo...710825F. doi:10.1038/ncomms10825. PMC 4786747. PMID 26953824.
  4. ^ Kear, Benjamin P.; Boles, Walter E.; Smith, Elizabeth T. (2003). "Unusual gut contents in a Cretaceous ichthyosaur". Proceedings of the Royal Society B. 270 (Suppl 2): S206–S208. doi:10.1098/rsbl.2003.0050. PMC 1809966. PMID 14667384.
  5. ^ a b Arkhangelsky, M.S. (1998). "On the Ichthyosaurian genus Platypterygius". Paleontological Journal. 32 (6): 611–615.
  6. ^ Maria Zammit, Rachel M. Norris & Benjamin P. Kear (2010). "The Australian Cretaceous ichthyosaur Platypterygius australis: a description and review of postcranial remains". Journal of Vertebrate Paleontology. 30 (6): 1726–1735. Bibcode:2010JVPal..30.1726Z. doi:10.1080/02724634.2010.521930. S2CID 85089080.
  7. ^ Fischer, V. (2012). "New Data on the Ichthyosaur Platypterygius hercynicus and Its Implications for the Validity of the Genus". Acta Palaeontologica Polonica. 57 (1): 123–134. doi:10.4202/app.2011.0007. S2CID 53355007.
  8. ^ a b Fischer, Valentin; Arkhangelsky, Maxim S.; Naish, Darren; Stenshin, Ilya M.; Uspensky, Gleb N.; Godefroit, Pascal (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. doi:10.1111/zoj.12158.
  9. ^ a b Fischer, V. (2016). "Taxonomy of Platypterygius campylodon and the diversity of the last ichthyosaurs". PeerJ. 4: e2604. doi:10.7717/peerj.2604. PMC 5075704. PMID 27781178.
  10. ^ "Mesozoic marine reptiles of Russia and other former Soviet Republics". The Age of Dinosaurs in Russia and Mongolia. Cambridge, UK: Cambridge University Press. 2000. pp. 187–210.
  11. ^ McGowan, C.; Motani, R. (2003). "Ichthyopterygia". Handbook of Paleoherpetology. 8. Munich, Germany: 175.
  12. ^ a b Zammit, M. (2012). "Cretaceous Ichthyosaurs: Dwindling Diversity, or the Empire Strikes Back?". Geosciences. 2 (2): 187–210. Bibcode:2012Geosc...2...11Z. doi:10.3390/geosciences2020011.
  13. ^ Nikolay G. Zverkov; Dmitry V. Grigoriev (2020). "An unrevealed lineage of platypterygiines (Ichthyosauria) with peculiar forefin structure and semiglobal distribution in the mid-Cretaceous (Albian–Cenomanian)". Cretaceous Research. 115: Article 104550. Bibcode:2020CrRes.11504550Z. doi:10.1016/j.cretres.2020.104550. S2CID 225721312.
  14. ^ Cortés, D.; Maxwell, E.E.; Larsson, H.C.E. (2021). "Re-appearance of hypercarnivore ichthyosaurs in the Cretaceous with differentiated dentition revision of Platypterygius sachicarum (Reptilia:Ichthyosauria, Ophthalmosauridae) from Colombia". Journal of Systematic Palaeontology. 19 (14): 969–1002. Bibcode:2021JSPal..19..969C. doi:10.1080/14772019.2021.1989507. S2CID 244512087.
  15. ^ Maxwell, E.E.; Kear, B.P. (2010). "Postcranial anatomy of Platypterygius americanus (Reptilia: Ichthyosauria) from the Cretaceous of Wyoming". Journal of Vertebrate Paleontology. 30 (4): 1059–1068. Bibcode:2010JVPal..30.1059M. doi:10.1080/02724634.2010.483546. S2CID 85817541.
  16. ^ 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. Bibcode:2019JSPal..17.1183Z. doi:10.1080/14772019.2018.1515793. S2CID 91912834.
  17. ^ a b Nikolay G. Zverkov; Megan L. Jacobs (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: 228–275. doi:10.1093/zoolinnean/zlaa028.
  18. ^ Campos, L.; Fernández, M. S.; Bosio, V.; Herrera, Y.; Manzo, A. (2024). "Revalidation of Myobradypterygius hauthali Huene, 1927 and the phylogenetic signal within the ophthalmosaurid (Ichthyosauria) forefins". Cretaceous Research. 157. 105818. Bibcode:2024CrRes.15705818C. doi:10.1016/j.cretres.2023.105818.
  19. ^ a b Fischer, Valentin; Arkhangelsky, Maxim S.; Naish, Darren; Stenshin, Ilya M.; Uspensky, Gleb N.; Godefroit, Pascal (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. doi:10.1111/zoj.12158.
  20. ^ Páramo, M.E. (1997). "Platypterygius sachicarum (Reptilia, Ichthyosauria) nueva especie del Cretácico de Colombia". Revista INGEOMINAS. 6: 1–12.

Bibliography

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Further reading

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  • Long, J.A., Dinosaurs of Australia and New Zealand, UNSW Press, Australia 1998
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