| 词条 | Parahelicoprion |
| 释义 |
| fossil_range = Early Permian ~{{Fossil range|298.9|295}} | image = Parahelicoprion clerci.jpg | taxon = Parahelicoprion | authority = Karpinsky, 1924 | type_species = Helicoprion clerci | type_species_authority = Karpinsky, 1916 | subdivision_ranks = Species | subdivision =
}} Parahelicoprion is an extinct genus of shark-like eugeneodontid holocephalids from the Permian of the Ural Mountains and Copacabana Formation, Bolivia.[1] The genus name, from "nearly coiled saw" in Greek, directly refers to Helicoprion, a related holocephalid that shares similar traits to it, including the helical whorl of teeth. DescriptionOne of the primary qualities that separate Parahelicoprion from Helicoprion is the shape, thickness, and angle of the tooth whorl. Its 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 those of other whorl-tooth sharks, resulting in a depreciated spiral, growing only half of the teeth a Helicoprion would grow in its lifetime. The tooth spiral also was able to indicate the age of the eugeneodontidans in question.[3] Parahelocoprion is estimated to have grown to lengths of around 12 m.{{citation needed|date=May 2016}} It was once thought to be the largest of its family; in 2013, however, a tooth whorl of a large Helicoprion was described, indicating that the genus could grow to larger sizes. The fossils of Parahelicoprion indicate an animal that was overall more slender and less heavy than Helicoprion despite being comparably sized.[4]PaleobiologyParahelicoprion 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.[5]References{{Portal|Paleontology|Sharks|Permian|Prehistory of Asia|Prehistory of South America}}1. ^{{cite journal | title=Chondrichthyan and actinopterygian remains from theLower Permian Copacabana Formation of Bolivia | author=Merino-Rodo, Dagmar| journal=Geobios | year=1986 | volume=19 | issue=4 | pages=479–493 | doi=10.1016/S0016-6995(86)80005-5|display-authors=etal}} {{Taxonbar|from=Q7134758}}{{paleo-cartilaginous-fish-stub}}2. ^http://dinonews.net/forum/paleoactus.php?msg=168926 Parahelicoprion and Agassizodontidea 3. ^Brad Matsen and Ray Troll (October 25, 2012). "Planet Ocean: A Story of Life, the Sea, and Dancing to the Fossil Record". 4. ^{{Cite web | url=http://www.eartharchives.org/articles/buzzsaw-toothed-leviathans-cruised-the-ancient-seas/ | title=Buzzsaw-toothed leviathans cruised the ancient seas}} 5. ^http://fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=34463 9 : Agassizodontidae|Prehistoric cartilaginous fish genera|Permian cartilaginous fish|Permian fish of Asia|Fossils of Russia|Prehistoric fish of South America|Permian Bolivia|Fossils of Bolivia|Fossil taxa described in 1916 |
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