Helicoprion
Helicoprion is an extinct genus of cartilaginous 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. It is one of the most popular sharks of all time. It was always assumed that the Helicoprion was a shark, but it is more closely related to ratfish.
Description
It had skeletons made of cartilage. As a result, the entire body disintegrated once it began to decay, unless preserved by exceptional circumstances. This can make it difficult to draw precise conclusions on the full body appearance of Helicoprion.
The tooth was unusual-looking. Many shark fans call the tooth a tooth whorl. The largest known Helicoprion tooth whorl, specimen IMNH 49382 representing an unknown species, reached 56 cm (22 in) in diameter and 14 cm (5.5 in) in crown height, which would have belonged to an individual over 7.6 m (25 ft) in length.
Tooth whorls
Main article: Tooth whorl
A tooth whorl is a structure found on the Helicoprion. Almost all Helicoprion specimens are known solely from tooth whorls, which is a name shark lovers call when they see a tooth whorl.
Species
- Helicoprion bessonowi Karpinsky, 1899 (type)
- Helicoprion davisii Woodward, 1886
- Helicoprion ergassaminon Bendix-Almgreen, 1966
Other material
Several large whorls are difficult to assign to any particular species group, H. svalis among them. IMNH 14095, a specimen from Idaho, appears to be similar to H. bessonowi, but it has unique flange-like edges on the apices of its teeth. IMNH 49382, also from Idaho, has the largest known whorl diameter at 56 cm (22 in) for the outermost volution (the only one preserved), but it is incompletely preserved and still partially buried. H. mexicanus, named by F.K.G. Müllerreid in 1945, was supposedly distinguished by its tooth ornamentation.
Its holotype is currently missing, though its morphology was similar to that of IMNH 49382. In 1922, Karpinsky named a new species of Helicoprion, H. ivanovi, from Gzhelian (latest Carboniferous) strata near Moscow. However, this species has subsequently been removed from Helicoprion and placed as a second species of the related eugeneodont Campyloprion.
What the tooth whorl looked like
Hypotheses for the placement and identity of Helicoprion's tooth whorls were controversial from the moment it was discovered. Woodward (1886), who referred the first known Helicoprion fossils to Edestus, discussed the various hypotheses concerning the nature of Edestus fossils.
Karpinsky's hypothesis of the placement of the tooth whorl was putting it on the nose. Many people said that "the tooth whorl on the nose looks so weird." It now has its tooth whorl in its lower jaw.
In popular culture
Helicoprion was a famous animal because it has been found in many websites. People have given it the name buzzsaw shark.
Helicoprion Media
Diagram of the teeth within the spiral
Restoration of the skull of Helicoprion, based on IMNH 37899
Cross section of the jaw of Helicoprion, drawn after figure 7 in Eating with a saw for a jaw: Functional morphology of the jaws and tooth-whorl in Helicoprion davisii in Journal of Morphology by Jason B. Ramsay, Cheryl D. Wilga, Leif Tapanila Jesse Pruitt, Alan Pradel, Robert Schlader, and Dominique A. Didier. Interior teeth of the whorl not shown.
Jaw motion of Helicoprion, based on figures in Eating with a saw for a jaw: Functional morphology of the jaws and tooth-whorl in Helicoprion davisii in Journal of Morphology by Jason B. Ramsay, Cheryl D. Wilga, Leif Tapanila Jesse Pruitt, Alan Pradel, Robert Schlader, and Dominique A. Didier
Helicoprion ferrieri (Hay, 1907) - fossil shark tooth whorl from the Permian of Idaho, USA. (IMNH 37899, Idaho Museum of Natural History, Idaho State University, Pocatello, Idaho, USA)*This remarkable fossil is a symphyseal tooth whorl from the lower jaw of an edestoid shark.
FMNH PF 74455, a H. davisii (=H. ferrieri) tooth-whorl found in the Glass Mountains of Texas
Cast of specimen TsNIGR 1/1865, a well-preserved Helicoprion bessonowi tooth-whorl from the Ural Mountains of Russia
IMNH 30900, a Helicoprion ergassaminon tooth-whorl from Gay Mine in Bingham County, Idaho.
Alexander Karpinsky's 1899 hypothesis of the placement of the tooth whorl on H. bessonowi.
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Related pages
References
- Viegas, Jennifer (February 27, 2013). "Ancient shark relative had buzzsaw mouth". science.nbcnews.com.
- Grogan, Eileen D.; Lund, Richard; Didier, Dominique (1999). "Description of the chimaerid jaw and its phylogenetic origins". Journal of Morphology. 239 (1): 45–59. doi:10.1002/(SICI)1097-4687(199901)239:1<45::AID-JMOR3>3.0.CO;2-S. ISSN 1097-4687. PMID 29847876. S2CID 44140851.
Other websites
- Helicoprion on English Wikipedia
- Sharks portal
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