Acanthorhachis

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Acanthorhachis
Temporal range: Visean– Westphalian
Acanthorhachis spinatus.png
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: incertae sedis
Family: Listracanthidae
Genus: Acanthorhachis
Martill, Del Strother, & Gallien, 2013
Species:
A. spinatus
Binomial name
Acanthorhachis spinatus
Martill, Del Strother, & Gallien, 2013

Acanthorhachis is an enigmatic extinct genus of chondrichthyan from the Carboniferous period. [1] Its name is derived from the Greek word acanthos meaning "spine" and the Greek suffix for spine, -rhachis. This is due to the spine-like dermal denticles and their subsidiary spines, which coated the exterior of the animal. The authors who erected this genus suggested the common name "The Spiny Spined Shark." It is closely related to Listracanthus . It differs from it in the size, structure, and distribution of dermal spines. It is currently monotypic, containing only the species A. spinatus. This shark is thus far only described from the British Isles. Acanthorhachis was first described from the Westphalian-aged lower coal measures of Yorkshire, England. [2] It occurs rarely in Viséan-aged Eyam Limestone of Derbyshire, England. [3]

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<i>Listracanthus</i> Extinct genus of cartilaginous fishes

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<span class="mw-page-title-main">Listracanthidae</span> An extinct family of cartilaginous fish

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Squatinactis is a genus of extinct elasmobranch Chondrichthyes known from the Carboniferous aged Bear gulch limestone in Montana. This fish was discovered in 1974 by Richard Lund. The type specimen, named CMNH 46133, consists of a brain case, poorly preserved jaws and gills, a pectoral fin, and a partial vertebral axis. This creatures most startling feature were its broad pectoral fins which resembled those of Stingrays and Angel sharks (Squatina). The holotype specimen has about 15 teeth in its jaw. This creature is named after the angel shark. Teeth found in Derbyshire, England have been tentatively identified as those belonging to S. caudispinatus.

References

  1. "Fossilworks: Acanthorhachis". fossilworks.org. Retrieved 17 December 2021.
  2. MARTILL, DAVID M.; DEL STROTHER, PETER J. A.; GALLIEN, FLORENCE (2013-07-08). "Acanthorhachis, a new genus of shark from the Carboniferous (Westphalian) of Yorkshire, England". Geological Magazine. 151 (3): 517–533. doi:10.1017/s0016756813000447. ISSN   0016-7568. S2CID   129437036.
  3. Smith, Roy; Martill, David M.; Duffin, Christopher (2017-06-01). "The shark-beds of the Eyam Limestone Formation (Lower Carboniferous, Viséan) of Steeplehouse Quarry, Wirksworth, Derbyshire, UK". Proceedings of the Geologists' Association. 128 (3): 374–400. doi:10.1016/j.pgeola.2017.04.004. ISSN   0016-7878.