Helicoprionidae

Helicoprionidae; Temporal range: 358–252 Ma PreꞒ Ꞓ O S D C P T J K Pg N Early Carboniferous to Late Permian
	Helicoprion
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Subclass:	Holocephali
Order:	†Eugeneodontida
Clade:	†Edestoidea
Family:	†Helicoprionidae; Karpinsky, 1911
Type genus
	Helicoprion; Karpinsky, 1899
Type species
	Helicoprion bessonowi; Karpinsky, 1899
Genera
	Agassizodus; Arpagodus; Campyloprion; Helicoprion; Hunanohelicoprion; Karpinskiprion; Parahelicoprion?; Sarcoprion; Shaktauites; Sinohelicoprion; Toxoprion;
Synonyms
	Agassizodontidae Zangerl, 1981;

Helicoprionidae (synonym Agassizodontidae) is an extinct, poorly known family of bizarre holocephalids within the poorly understood order Eugeneodontida. Members of the Helicoprionidae possessed a unique "tooth-whorl" on the symphysis of the lower jaw and pectoral fins supported by long radials.^[2] The closest living relatives of the Helicoprionidae and all other eugeneodontids are the ratfishes. The anatomy of the tooth-whorl differed amongst genus and species, some possessing complete spirals (such as those of Helicoprion), others possessing halved spirals (seen in Parahelicoprion), and some with wedged half-spirals (seen in Sarcoprion). Each tooth-whorl is thought to be adapted to a different type of prey, and a different predation strategy.^[3]

References

^ ^a ^b Lebedev, O. A. (2009). "A new specimen of Helicoprion Karpinsky, 1899 from Kazakhstanian Cisurals and a new reconstruction of its tooth whorl position and function". Acta Zoologica. 90: 171–182. doi:10.1111/j.1463-6395.2008.00353.x.
^ Cicimurri, D. J.; Fahrenbach, M. D. (2002). "Chondrichthyes from the upper part of the Minnelusa Formation (Middle Pennsylvanian: Desmoinesian), Meade County, South Dakota" (PDF). Proceedings of the South Dakota Academy of Science. 81: 81–92.
^ Fishes and the Break-up of Pangaea edited by Lionel Cavin, A. E. Longbottom, Martha Richter (1825)

External links

Palaeos Vertebrates 70.100 Chondrichthyes: Eugnathostomata at paleos.com
JSTOR: Journal of PaleontologyVol. 70, No. 1 (Jan., 1996), pp. 162-165
More about Chondrichthyes Archived 2017-10-22 at the Wayback Machine at Devonian Times

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[Lebedev-1] Lebedev, O. A. (2009). "A new specimen of Helicoprion Karpinsky, 1899 from Kazakhstanian Cisurals and a new reconstruction of its tooth whorl position and function". Acta Zoologica. 90: 171–182. doi:10.1111/j.1463-6395.2008.00353.x.

[2] Cicimurri, D. J.; Fahrenbach, M. D. (2002). "Chondrichthyes from the upper part of the Minnelusa Formation (Middle Pennsylvanian: Desmoinesian), Meade County, South Dakota" (PDF). Proceedings of the South Dakota Academy of Science. 81: 81–92.

[3] Fishes and the Break-up of Pangaea edited by Lionel Cavin, A. E. Longbottom, Martha Richter (1825)

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