Eriptychiida

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Eriptychiida
Temporal range: Late Ordovician, 450  Ma
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Overview of Eriptychius americanus PF 1795.png
Specimen of Eriptychius americanus
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Agnatha
Class: Pteraspidomorpha
Subclass: Heterostracomorphi
Infraclass: Eriptychiida
Tarlo 1962
Order: Eriptychiiformes
Ørvig 1958 [1]
Families

Eriptychiida is an extinct marine taxon of vertebrate in the group Pteraspidomorphi.

Contents

The order contains the genus, Eriptychius , and fossilized specimens from this genus have been found in the Gull River Formation of Ontario, the Harding Formation of Colorado, and the Bighorn Dolomite of Wyoming. The group contains two documented species: Eriptychius americanus and Eriptychius orvigi.

Characteristics

The structure of the dentine of eriptychiids is in many respects closer to that of heterostracans than to that of astraspids. This is the only argument to place them, as the closest relatives to heterostracans, among the Ordovician vertebrates. A 450 million years old fossil of eriptychius shows it had a skull consisting of separate cartilage plates, with the frontal plates being mineralized, and that a thin body armor covered the head. It appears to be the first step towards a more solid braincase in vertebrates. [2]

Taxonomy

In study at 2023, Eriptychius is placed just under Vertebrata, not considering class or order. [6]

See also

References

  1. Ørvig, T. 1958. Pycnaspis splendens, new genus, new species, a new ostracoderm from the Upper Ordovician of North America. Proceedings of the United States National Museum 108(3391): 1-23. DOI: 10.5479/si.00963801.108-3391.1
  2. Ancient fish reveals how vertebrates put their heads together
  3. Haaramo, Mikko (2003). "Pteraspidomorphi". in Mikko's Phylogeny Archive. After Carroll, 1988, and Janvier, 1997. Retrieved 26 October 2013.
  4. Nelson, Joseph S.; Grande, Terry C.; Wilson, Mark V. H. (2016). Fishes of the World (5th ed.). John Wiley & Sons. ISBN   9781118342336.
  5. van der Laan, Richard (2018). "Family-group names of fossil fishes" (PDF). European Journal of Taxonomy (466): 1–167. doi: 10.5852/ejt.2018.466 .
  6. Dearden, Richard P.; Lanzetti, Agnese; Giles, Sam; Johanson, Zerina; Jones, Andy S.; Lautenschlager, Stephan; Randle, Emma; Sansom, Ivan J. (2023-09-20). "The oldest three-dimensionally preserved vertebrate neurocranium". Nature. 621 (7980): 782–787. doi: 10.1038/s41586-023-06538-y . ISSN   1476-4687. PMC   10533405 . PMID   37730987.