Ctenoptychius

File:Recherches Poissons Fossiles vol. 3. Tab. 19.png

Ctenoptychius was named by naturalist Louis Agassiz in his work Recherches sur les poissons fossiles.{{Cite book |last=Agassiz |first=Louis |url=https://www.biodiversitylibrary.org/bibliography/4275 |title=Recherches sur les poissons fossiles ... |last2=Agassiz |first2=Louis |date=1833 |publisher=Petitpierre |location=Neuchatel |doi=10.5962/bhl.title.4275}}{{Cite journal |last=Downs |first=Jason Philip |last2=and Daeschler |first2=Edward B. |date=2001-12-14 |title=Variation within a large sample of Ageleodus pectinatus teeth (Chondrichthyes) from the Late devonian of Pennsylvania, U.S.A. |url=https://www.tandfonline.com/doi/abs/10.1671/0272-4634%282001%29021%5B0811%3AVWALSO%5D2.0.CO%3B2 |journal=Journal of Vertebrate Paleontology |volume=21 |issue=4 |pages=811–814 |doi=10.1671/0272-4634(2001)021[0811:VWALSO]2.0.CO;2 |issn=0272-4634|url-access=subscription }} Agassiz considered the genus to encompass three species: C. apicalis, C. denticulatus, and C. pectinatus, with C. apicalis being the type species. All three species were diagnosed based on isolated teeth from the Carboniferous of England, and were united by the presence of large serrations on the tooth crown.{{Cite book |last=Ginter |first=Michał |title=Handbook of paleoichthyology: teeth |last2=Hampe |first2=Oliver |last3=Duffin |first3=Christopher J. |date=2010 |publisher=F. Pfeil |isbn=978-3-89937-116-1 |location=München |pages=147-150}} Subsequent authors have assigned additional species based on tooth-like structures with similar serrations, including fossils that have since been identified as the sex organs of the tetrapodomorph Ophiderpeton.{{Cite journal |last=Moodie |first=Roy L. |date=1908 |title=THE CLASPING ORGANS OF EXTINCT AND RECENT AMPHIBIA |url=https://www.journals.uchicago.edu/doi/10.2307/1535616 |journal=The Biological Bulletin |language=en |volume=14 |issue=4 |pages=249–259 |doi=10.2307/1535616 |issn=0006-3185|url-access=subscription }}{{Cite book |last= |url=https://www.biodiversitylibrary.org/bibliography/61854 |title=Catalogue of the fossil fishes in the British Museum (Natural History) |last2= |first2= |last3=Woodward |first3=Arthur Smith |last4=Woodward |first4=G. M. |date=1889 |publisher=British Museum of Natural History |volume=1 |location=London |pages=155 |doi=10.5962/bhl.title.61854}} Large serrations or cusplets are now known to occur in many unrelated genera of Paleozoic chondrichthyan, only C. apicalis is considered a member of the genus, and other species have been reassigned to different genera or,{{Cite book |last=Zangerl |first=Rainer |title=Chondrichthyes 1: Paleozoic Elasmobranchii |publisher=Friedrich Pfell |year=1981 |isbn=978-3899370454 |series=Handbook of Paleoichthyology |publication-date=January 1, 1981 |pages=95-97 |language=English}} as in the North American "C. stevensoni", have been regarded as probable synonyms of the type species. The holotype tooth of C. apicalis is now missing.

Articulated body fossils of Ctenoptychius apicalis were described from the coal measures of North Staffordshire in 1890. These preserve the front portion of the body and pectoral fins, the coating of dermal denticles, the cartilaginous jaws, and disarticulated teeth.{{Cite journal |last=W |first=A. S. |date=1890 |title=III.—The Geological Features of the North Staffordshire Coal-Fields, their Organic Remains, their Range and Distribution; with a Catalogue of the Fossils of the Carboniferous System of North Staffordshire. |url=https://www.google.com/books/edition/The_Geological_Features_of_the_North_Sta/4CXA2PlnFqkC?hl=en |journal=Geological Magazine |language=en |volume=7 |issue=9 |pages=141-152 |doi=10.1017/S0016756800188144 |issn=1469-5081|url-access=subscription }}{{Cite book |last=Gibson |first=Walcot |url=https://archive.org/details/cu31924057829776/page/354/mode/2up |title=The geology of the north Staffordshire coalfields |last2=Barrow |first2=George |last3=Wedd |first3=Charles Bertie |last4=Ward |first4=John |date=1905 |publisher=London, Printed for H. M. Stationery off., by Wyman and sons, limited |others=Cornell University Library |pages=298}} However, the preservation of this material has been noted as poor, and details of the anatomy are difficult to make out.

The taxon "Ctenoptychius" korni is known from complete, articulated body fossils from the Late Permian-age Kupferschiefer of Germany.{{Cite journal |last=Brandt |first=Silvio |date=1996 |title=Janassa korni (Weigelt) — Neubeschreibung eines petalodonten Elasmobranchiers aus dem Kupferschiefer und Zechsteinkalk (Perm) von Eisleben (Sachsen-Anhalt) |url=http://link.springer.com/10.1007/BF02988089 |journal=Paläontologische Zeitschrift |language=de |volume=70 |issue=3-4 |pages=505–520 |doi=10.1007/BF02988089 |issn=0031-0220|url-access=subscription }}{{Cite journal |last=Brandt |first=Silvio |date=2009 |title=Über Neufunde von Janassa korni (WEIGELT), einen petalodonten Elasmobranchier aus dem Kupferschiefer (Ober-Perm) von Eisle - ben und Sangerhausen (Sachsen-Anhalt) (About new finds and informations of the petalodontid Janassa korni from the Kupferschiefer (Upper Permian) of Eisleben and Sangerhausen, Germany) |url=https://www.researchgate.net/publication/275037522_Uber_Neufunde_von_Janassa_korni_WEIGELT_einen_petalodonten_Elasmobranchier_aus_dem_Kupferschiefer_Ober-Perm_von_Eisle_-_ben_und_Sangerhausen_Sachsen-Anhalt_About_new_finds_and_informations_of_the_peta |journal=Veröffentlichungen Naturhist. Museum Schleusingen |volume=24 |pages=15-26 |via=ResearchGate}}{{Cite journal |last=Lund |first=R. |last2=Grogan |first2=E. D. |last3=Fath |first3=M. |date=2014 |title=On the relationships of the Petalodontiformes (Chondrichthyes) |url=http://link.springer.com/10.1134/S0031030114090081 |journal=Paleontological Journal |language=en |volume=48 |issue=9 |pages=1015–1029 |doi=10.1134/S0031030114090081 |issn=0031-0301|url-access=subscription }} This species has variously been assigned to Ctenoptychius and the distantly related genus Janassa, but has alternatively been suggested to belong to neither due to lacking the distinctive features of both genera.

File:Ctenoptychius apicalis diagram.pngThe tooth crowns of Ctenoptychius apicalis had between three and nine cusplets, with the centermost being the largest. The root (or base) of the tooth was wide and rounded. The overall shape of the teeth was flattened.{{Cite book |last=Zittel |first=Karl Alfred von |url=https://archive.org/details/textbookofpaleon0002zitt |title=Text-book of paleontology |date=1925 |publisher=London : Macmillan and Co. |others=Internet Archive |pages=89-90 |translator-last=Eastman |translator-first=Charles R.}} In life, the teeth were arranged in multiple tightly packed rows in the upper and lower jaws.

The body of Ctenoptychius was depressiform and the pectoral fins were large and broad. The body shape was similar to a living ray or angelshark,{{Cite journal |last=Robb |first=Albert J. |date=2003 |title=Notes on the occurrence of some petalodont shark fossils from the Upper Pennsylvanian rocks of northeastern Kansas |url=http://www.bioone.org/doi/abs/10.1660/0022-8443%282003%29106%5B0071%3ANOTOOS%5D2.0.CO%3B2 |journal=Transactions of the Kansas Academy of Science |language=en |volume=106 |issue=1 & 2 |pages=71–80 |doi=10.1660/0022-8443(2003)106[0071:NOTOOS]2.0.CO;2 |issn=0022-8443|url-access=subscription }} as well as to the distantly related Janassa bituminosa which the head and fins of Ctenoptychius closely resembled. Nothing is known about the dorsal fin or pelvic fin anatomy of C. apicalis, but there is no evidence of defensive spines on the dorsal fin. The known portion of the body was coated by dermal denticles, which were most numerous around the head. The anatomy of the denticles is not known in detail.

Due to its ray-like shape, Ctenoptychius is assumed to have been a bottom-dweller. Petalodont fossils are known primarily from shallow marine environments, and the stomach contents of Janassa imply that at least some members of the group were omnivorous bottom feeders that targeted hard-shelled invertebrates.

• Belantsea, another belantseid petalodont known from body fossils
• List of prehistoric cartilaginous fish genera

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{{Chondrichthyan genera|A.}}{{Taxon identifiers|from=Q41214916}}

Category:Petalodontiformes

Category:Carboniferous cartilaginous fish

Category:Prehistoric cartilaginous fish genera

Category:Fossil taxa described in 1838

Category:Carboniferous fish of Europe