Helicoprionidae

Helicoprionidae; Temporal range: 360–251 Ma PreꞒ Ꞓ O S D C P T J K Pg N Early Carboniferous to Early Triassic
	Outdated reconstruction of Helicoprion bessonovi
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Subclass:	Holocephali
Order:	†Eugeneodontida
Family:	Helicoprionidae; Karpinsky, 1911
Type genus
	Agassizodus; St John and Worthen, 1875
Type species
	Lophodus variabillis; Newberry and Worthen 1870
Genera
	Agassizodus; Arpagodus; Campyloprion; Helicoprion; Hunanohelicoprion; Parahelicoprion; Sarcoprion; Shaktauites; Sinohelicoprion; Toxoprion;
Synonyms
	Agassizodontidae Zangerl, 1981;

Helicoprionidae is an extinct, poorly known family of bizarre holocephalids within the poorly understood order Eugeneodontida. Members of Helicoprionidae possessed a unique "tooth-whorl" on the symphysis of the lower jaw as well as pectoral fins supported by long radials.^[2] The closest living relatives of 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" (PDF). Acta Zoologica. 90: 171–182. doi:10.1111/j.1463-6395.2008.00353.x. Apart from the type genus, Agassizodus St John and Worthen, 1875; Parahelicoprion Karpinsky, 1924; Campyloprion Eastman, 1902; Sarcoprion Nielsen, 1952; Toxoprion Hay, 1909; Sinohelicoprion Liu and Chang, 1963; Hunanohelicoprion Liu, 1994 and Shaktauites Tchuvashov, 2001.
^ "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. 2002. {{cite journal}}: Unknown parameter |authors= ignored (help)
^ 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 at Denovian 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" (PDF). Acta Zoologica. 90: 171–182. doi:10.1111/j.1463-6395.2008.00353.x. Apart from the type genus, Agassizodus St John and Worthen, 1875; Parahelicoprion Karpinsky, 1924; Campyloprion Eastman, 1902; Sarcoprion Nielsen, 1952; Toxoprion Hay, 1909; Sinohelicoprion Liu and Chang, 1963; Hunanohelicoprion Liu, 1994 and Shaktauites Tchuvashov, 2001.

[2] "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. 2002. {{cite journal}}: Unknown parameter |authors= ignored (help)

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

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