Hexanchiformes

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Hexanchiformes
Temporal range: Middle Jurassic–Recent [1]
Frilled shark, Chlamydoselachus anguineus
Scientific classification
Kingdom:
Phylum:
Class:
Subclass:
Superorder:
Order:
Hexanchiformes

de Buen, 1926
Families

Chlamydoselachidae
Hexanchidae

Hexanchiformes is the order consisting of the most primitive types of sharks, and numbering just six extant species. Fossil sharks that were apparently very similar to modern sevengill species are known from Jurassic specimens.[2]

Hexanchiform sharks have only one dorsal fin, either six or seven gill slits, and no nictitating membrane in the eyes.

The frilled shark, Chlamydoselachus anguineus, is very different from the cow sharks, and it has been proposed that it be moved to its own order Chlamydoselachiformes.

Classification

Living species

Extinct species

Notidanodon sp. fossil at the Geological Museum, Copenhagen

See also

References

  1. ^ Froese, Rainer, and Daniel Pauly, eds. (2009). "Hexanchiformes" in FishBase. January 2009 version.
  2. ^ Allen, 45
  • Froese, Rainer, and Daniel Pauly, eds. (2011). "Chlamydoselachidae" in FishBase. February 2011 version. (Fish Base family reference)
  • Froese, Rainer, and Daniel Pauly, eds. (2011). "Hexanchidae" in FishBase. February 2011 version. (Fish Base family reference)
  • Allen, Thomas B. The Shark Almanac. New York: The Lyons Press, 1999. ISBN 1-55821-582-4