page_title: Helicoprion
section_title: Description
hierarchical_section_title: Helicoprion / Description
caption_attribution_description: English: Reconstruction of Helicoprion bessonovi from Early Permian of Middle Ural Русский: Helicoprion bessonovi из ранней перми Среднего Урала
context_page_description: Helicoprion is a genus of extinct, shark-like eugeneodontid holocephalid fish. Almost all fossil specimens are of spirally arranged clusters of the individuals' teeth, called "tooth whorls"— the cartilaginous skull, spine, and other structural elements have not been preserved in the fossil record, leaving scientists to make educated guesses as to its anatomy and behavior. Helicoprion lived in the oceans of the early Permian 290 million years ago, with species known from North America, Eastern Europe, Asia, and Australia. The closest living relatives of Helicoprion are the chimaeras.
context_section_description: In 2011, a tooth whorl from a Helicoprion was discovered in the Phosphoria site in Idaho. The tooth whorl measured 45 cm (18 in) in length. Comparisons with other Helicoprion specimens show that the animal that sported this whorl would have been 10 m (33 ft) in length, and another, even bigger tooth whorl that was discovered in 1980s (but was not published until 2013) which the discoverers dubbed IMNH 49382 or "Boise" was discovered at the same site. The whorl is incomplete, but in life it would have been 60 cm (24 in) long and would have belonged to an animal that possibly exceeded 12 m (39 ft) in length, making Helicoprion the largest known eugeneodont.
caption: Illustration of H. bessonowi
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