Parahelicoprion
| Parahelicoprion Temporal range: Early Permian
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| Genus: | Parahelicoprion Karpinsky, 1924
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| Helicoprion clerci Karpinsky, 1916
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Parahelicoprion is an extinct genus of shark-like eugeneodontid holocephalid from the Permian of the Ural Mountains and South America.[1] Its name is a derivation of Helicoprion, from the Ancient Greek words "Nearly coiled saw", another holocephalid that shares similar traits to it, including the helical whorl of teeth. One of the primary qualities that separate Parahelicoprion from the aforementioned Helicoprion is the shape, thickness and angle of the tooth whorl. This whorl sharks teeth protrude outwards not like a tightly coiled saw but instead a curved arrangement of cutting blades indicating it relied less on crushing slow-moving invertebrates and catching squid and other small mollusk prey, but inflicting traumatic damage against more durable, faster prey.[2] Their teeth grew at a much slower pace than that of other whorl-tooth sharks, resulting in a depreciated spiral, growing only half of the teeth a Helicoprion would grow in its life time. The tooth spiral also was able to indicate the age of the eugeneodontidans in question. [3]
Description
Parahelocoprion is estimated to have grown to lengths of around 12 meters or so.[citation needed] It was once thought that Parahelicoprion was the largest of its family, but in 2013, a tooth whorl of a yet to be named species of Helicoprion was described and indicated that the genus Helicoprion could grow to lengths of more than 12 meters. Although Parahelicoprion is about as long, the fossils indicate an animal that was overall more slender than Helicoprion, which means an animal that was less heavy.[4]
It was once believed that Parahelicoprion reached lengths of up to 30 meters in length, but this was based on eel proportions instead of the classic, shark-like look of eugeneodonts. The figure was later discarded.[5]
Paleobiology
Parahelicoprion is thought to have been a nektonic carnivore that probably preyed upon a variety of different species, using its blade-like teeth to cut at exposed flesh like a hatchet or wedge.[6]
References
- ^ Merino-Rodo, Dagmar; et al. (1986). "Chondrichthyan and actinopterygian remains from theLower Permian Copacabana Formation of Bolivia". Geobios. 19 (4): 479–493. doi:10.1016/S0016-6995(86)80005-5.
- ^ http://dinonews.net/forum/paleoactus.php?msg=168926 Parahelicoprion and Agassizodontidea
- ^ Brad Matsen and Ray Troll (October 25, 2012). "Planet Ocean: A Story of Life, the Sea, and Dancing to the Fossil Record".
- ^ http://www.eartharchives.org/articles/buzzsaw-toothed-leviathans-cruised-the-ancient-seas/
- ^ https://diloraptor.wordpress.com/2015/03/26/parahelicoprion-and-size-problems/
- ^ http://fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=34463
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