Helicoprionidae

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]

Helicoprionidae
Helicoprion
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: †Eugeneodontida
Clade: †Edestoidea
Family: †Helicoprionidae
Karpinsky, 1911
Type genus
Helicoprion
Karpinsky, 1899[1]
Type species
Helicoprion bessonowi
Karpinsky, 1899
Genera
Synonyms
  • Agassizodontidae Zangerl, 1981[1]

References
  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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