Mongolepidida Explained

The Mongolepidida is an order of primitive elasmobranchs that lived during the Late Silurian and Early Devonian periods of Russia and Mongolia, with possible fragmentary remains dating back to the Katian epoch of the Late Ordovician (c.450 Ma). The three known genera are: Elegestolepis,[1] Mongolepis[2] and Polymerolepis.[3] [4] [5] [6] They are only known from fragmentary placoid scales, so their appearance is unknown. The oldest of these scales have been dated back to the Ludlow epoch (427.4 Ma to 423 Ma), making the members of the Mongolepidida possibly the oldest sharks known to date.[7]

Although the placoid scales of the Mongolepidida are accepted to be those of sharks, subtle differences in the scales suggest that they may have been quite different in appearance to modern sharks. It is not known what they looked like due to the fragmentary nature of the known remains.[8]

Notes and References

  1. Web site: Elestegolepis. www.planetsharkdivers.com. 12 August 2020. 24 October 2020. https://web.archive.org/web/20201024153546/https://planetsharkdivers.com/elegestolepis/. dead.
  2. Web site: Mongolepis. www.planetsharkdivers.com.
  3. Web site: Polymerolepis. www.planetsharkdivers.com.
  4. Andreev . Plamen . Coates . Michael I. . Karatajūtė-Talimaa . Valentina . Shelton . Richard M. . Cooper . Paul R. . Wang . Nian-Zhong . Sansom . Ivan J. . 2016 . The systematics of the Mongolepidida (Chondrichthyes) and the Ordovician origins of the clade . PeerJ . 4 . e1850 . 10.7717/peerj.1850 . 4918221 . 27350896 . free .
  5. Karatajùtè-Talimaa . Valentina . 1 January 1995 . The Mongolepidida: Scale structure and systematic position . 14 August 2020 . Geobios . Premiers Vertandébrandés et Vertandébrandés Infandérieurs . 28 . 35–37 . en . 10.1016/S0016-6995(95)80083-2. 1995Geobi..28...35K . subscription .
  6. Andreev . Plamen . Zhao . Wenjin . Wang . Nian-Zhong . Meredith Smith . Moya . Li . Qiang . Cui . Xindong . Zhu . Min . Sansom . Ivan . 13 February 2020 . Early Silurian chondrichthyans from the Tarim Basin (Xinjiang, China) . PLOS ONE . 15 . 2 . e0228589 . 10.1371/journal.pone.0228589. 32053606 . 7018067 . 2020PLoSO..1528589A . free .
  7. Web site: The Paleobiology Database. paleobiodb.org. 5 May 2016.
  8. Web site: Prehistoric Sharks | Sharkopedia . 12 August 2020 . 12 July 2018 . https://web.archive.org/web/20180712122249/https://sharkopedia.discovery.com/shark-topics/prehistoric-sharks/#interactive-timeline-of-shark-evolution . dead .

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