Helicoprionidae

Helicoprionidae
Temporal range: 360–251 Ma

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Outdated reconstruction of Helicoprion bessonovi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[1]
Type species
Lophodus variabillis
Newberry and Worthen 1870
Genera
Synonyms
  • Agassizodontidae Zangerl, 1981[1]

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

  1. 1 2 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. ↑ 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)

External links

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