Helicoprion

Helicoprion
Temporal range: Cisuralian to Guadalupian (Artinskian to Roadian), 290–270 Ma
FHPR L2003-2, a Helicoprion davisii tooth-whorl from the Phosphoria Formation of Idaho, Utah Field House of Natural History
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Holocephali
Order: †Eugeneodontida
Family: †Helicoprionidae
Genus: †Helicoprion
Karpinsky, 1899
Type species
Helicoprion bessonowi
Karpinsky, 1899
Other species
  • H. davisii (Woodward, 1886), originally Edestus davisii
  • H. ergassaminon Bendix-Almgreen, 1966
Synonyms
Synonyms of H. davisii
  • H. ferrieri (Hay, 1907), originally Lissoprion ferrieri
  • H. jingmenense Chen, Cheng, & Yin, 2007
  • H. sierrensis Wheeler, 1939
Synonyms of H. bessonowi
  • H. nevadensis Wheeler, 1939
Indeterminate species
  • H. karpinskii Obruchev, 1953
  • H. mexicanus Mullerried, 1945
  • H. svalis Siedlecki, 1970
  • H.? clerci Karpinsky, 1916

Helicoprion is an extinct genus of shark-like[1] eugeneodont fish. Almost all fossil specimens are of spirally arranged clusters of the individuals' teeth, called "tooth whorls", which in life were embedded in the lower jaw. As with most extinct cartilaginous fish, the skeleton is mostly unknown. Fossils of Helicoprion are known from a 20 million year timespan during the Permian period from the Artinskian stage of the Cisuralian (Early Permian) to the Roadian stage of the Guadalupian (Middle Permian).[2] The closest living relatives of Helicoprion (and other eugeneodonts) are the chimaeras, though their relationship is very distant.[3] The unusual tooth arrangement is thought to have been an adaption for feeding on soft bodied prey, and may have functioned as a deshelling mechanism for hard bodied cephalopods such as nautiloids and ammonoids. In 2013, systematic revision of Helicoprion via morphometric analysis of the tooth whorls found only H. davisii, H. bessonowi and H. ergassaminon to be valid, with some of the larger tooth whorls being outliers.[2]

Fossils of Helicoprion have been found worldwide, as the genus is known from Russia, Western Australia, China, Kazakhstan, Japan, Laos, Norway, Canada, Mexico, and the United States (Idaho, Nevada, Wyoming, Texas, Utah, and California). More than 50% of the fossils referred to Helicoprion are H. davisii specimens from the Phosphoria Formation of Idaho. An additional 25% of fossils are found in the Ural Mountains of Russia, belonging to the species H. bessonowi.[2]

  1. ^ Viegas, Jennifer (February 27, 2013). "Ancient shark relative had buzzsaw mouth". science.nbcnews.com.
  2. ^ a b c Cite error: The named reference pruitt was invoked but never defined (see the help page).
  3. ^ Tapanila, L.; Pruitt, J.; Pradel, A.; Wilga, C.D.; Ramsay, J.B.; Schlader, R.; Didier, D.A. (2013). "Jaws for a spiral-tooth whorl: CT images reveal novel adaptation and phylogeny in fossil Helicoprion". Biology Letters. 9 (2): 20130057. doi:10.1098/rsbl.2013.0057. PMC 3639784. PMID 23445952.