Eugeneodontiformes

{{Short description|Extinct group of cartilaginous fishes}} {{Automatic taxobox | fossil_range = {{fossil range|330.9|247.2|latest=247.2}} Early Carboniferous ([[Serpukhovian]]) to Early Triassic ([[Olenekian]]) | image = Romerodus orodontus (Mass Extinctions-BIG FIVE).jpg | image_caption = Body fossil of ''[[Romerodus|Romerodus orodontus]]'', a [[Caseodontidae|caseodont]] | image2 = Edestus mirus Hay.jpg | image2_caption = Jaw cartilage and teeth of ''[[Edestus]]'' (or ''[[Edestodus]]'') ''minor'', an edestoid | taxon = Eugeneodontiformes | authority = Zangerl, 1981 | subdivision_ranks = | subdivision = See text | synonyms = * Eugeneodontida }} [[File:Helicoprion Bessonovi2.jpg|right|thumb|Tooth whorl of ''[[Helicoprion bessonovi|Helicoprion bessonowi]]'', which in life was positioned in the lower jaw]]'''Eugeneodontiformes''' (also called '''Eugeneodontida''') is an [[extinct]] and poorly known [[order (biology)|order]] of [[Chondrichthyes|cartilaginous fishe]]s. They possessed "tooth-whorls" on the [[symphysis]] of either the lower or both jaws, and pectoral fins supported by long [[Fish fin|radials]]. They probably lacked [[pelvic fin]]s and anal fins.<ref name="Lebedev2009">{{cite journal|last1=Lebedev|first1=O.A.|year=2009|title=A new specimen of ''Helicoprion'' Karpinsky, 1899 from Kazakhstanian Cisurals and a new reconstruction of its tooth whorl position and function|url=https://www.researchgate.net/publication/249440368|journal=Acta Zoologica|volume=90|pages=171–182|doi=10.1111/j.1463-6395.2008.00353.x|issn=0001-7272}}</ref> The [[palatoquadrate]] was either fused to the skull or reduced in various members of the group. They are now determined to be within the [[Holocephali]]; their closest living relatives are [[chimaera]]s.<ref name="Tapanila_2013"/> The eugeneodonts are named after paleontologist [[Eugene S. Richardson, Jr.]]<ref name=":3">{{cite book |last=Zangerl |first=R. |date=1981 |title=Handbook of Paleoichthyology. Volume 3A. Chondrichthyes I. Paleozoic Elasmobranchi |location=Stuttgart |publisher=Gustav Fischer Verlag |isbn= 978-3-89937-045-4}}</ref> The group first appeared in the fossil record during the late [[Mississippian (geology)|Mississippian]] ([[Serpukhovian]]),<ref>{{Cite journal |last=Hodnett |first=John-Paul M. |last2=Elliott |first2=David K. |date=December 2018 |title=Carboniferous chondrichthyan assemblages from the Surprise Canyon and Watahomigi formations (latest Mississippian–Early Pennsylvanian) of the western Grand Canyon, Northern Arizona |url=https://www.cambridge.org/core/product/identifier/S0022336018000720/type/journal_article |journal=Journal of Paleontology |language=en |volume=92 |issue=S77 |pages=1–33 |doi=10.1017/jpa.2018.72 |issn=0022-3360|doi-access=free }}</ref> and the last eugeneodonts are known from the [[Early Triassic]] ([[Olenekian]]).<ref name="Scheyer et al 2014">{{cite journal |last1=Scheyer |first1=Torsten M. |last2=Romano |first2=Carlo |last3=Jenks |first3=Jim |last4=Bucher |first4=Hugo |title=Early Triassic Marine Biotic Recovery: The Predators' Perspective |journal=PLOS ONE |date=19 March 2014 |volume=9 |issue=3 |article-number=e88987 |doi=10.1371/journal.pone.0088987 |pmid=24647136 |pmc=3960099 |bibcode=2014PLoSO...988987S |doi-access=free }}</ref>

Members of the Eugeneodontiformes are further classified into two superfamilies and either four, five or six different families. The [[Helicoprionidae]] (or Agassizodontidae) and [[Edestidae]] are assigned to the superfamily '''Edestoidea''', the former containing genera such as ''[[Helicoprion]]'' and ''[[Parahelicoprion]]'', and the latter containing genera such as ''[[Edestus]]''. The family '''Helicampodontidae''' has been used for genera that do not closely resemble typical members of either of these two groups,<ref name="Lebedev2022">{{cite journal |last1=Lebedev |first1=O. A. |last2=Itano |first2=W. M. |last3=Johanson |first3=Z. |last4=Alekseev |first4=A. S. |last5=Smith |first5=M. M. |last6=Ivanov |first6=A. V. |last7=Novikov |first7=I. V. |date=2022 |title=Tooth whorl structure, growth and function in a helicoprionid chondrichthyan Karpinskiprion (nom. nov.) (Eugeneodontiformes) with a revision of the family composition |journal=Earth and Environmental Science Transactions of the Royal Society of Edinburgh |volume=113 |issue=4 |pages=337–360 |doi=10.1017/S1755691022000251}}</ref> and the family '''Lestrodontidae''' has been proposed for the genus ''[[Lestrodus]]''.<ref>{{Cite journal |last=Lebedev |first=Oleg A. |last2=Itano |first2=Wayne M. |last3=Duffin |first3=Christopher J. |last4=Ivanov |first4=Alexander O. |date=2026 |title=The earliest stem edestoid (Eugeneodontiformes, Chondrichthyes) from the Viséan (lower Carboniferous) of Tula Region, Central Russia, and a revision of Edestoidea |url=https://cdnsciencepub.com/doi/10.1139/cjz-2025-0140 |journal=Canadian Journal of Zoology |volume=104 |pages=1–24 |doi=10.1139/cjz-2025-0140 |issn=0008-4301|url-access=subscription }}</ref> The superfamily '''Eugeneodontoidei''' (traditionally '''Caseodontoidea''')<ref>{{Cite journal |last=Van der Laan |first=Richard |date=2018-10-11 |title=Family-group names of fossil fishes |url=http://www.europeanjournaloftaxonomy.eu/index.php/ejt/article/view/597 |journal=European Journal of Taxonomy |issue=466 |doi=10.5852/ejt.2018.466 |issn=2118-9773|doi-access=free }}</ref> includes the families [[Caseodontidae]] and [[Eugeneodontidae]], which were smaller and less-specialized than the edestoids.<ref name=":3" />

Some members of the superfamily Edestoidea are probably the largest marine animals of their time, though the body length estimates for both genera are somewhat speculative due to both only being known from skulls and teeth.<ref>{{Cite journal |last=Gayford |first=Joel H. |last2=Engelman |first2=Russell K. |last3=Sternes |first3=Phillip C. |last4=Itano |first4=Wayne M. |last5=Bazzi |first5=Mohamad |last6=Collareta |first6=Alberto |last7=Salas‐Gismondi |first7=Rodolfo |last8=Shimada |first8=Kenshu |date=2024 |title=Cautionary tales on the use of proxies to estimate body size and form of extinct animals |url=https://onlinelibrary.wiley.com/doi/10.1002/ece3.70218 |journal=Ecology and Evolution |language=en |volume=14 |issue=9 |doi=10.1002/ece3.70218 |issn=2045-7758 |pmc=11368419 |pmid=39224151}}</ref> The [[Late Carboniferous]] ''[[Edestus]]'' has been estimated to reach exceed {{convert|6.7|m|ft}} in length, with some [[Early Permian]] ''[[Helicoprion]]'' suggested to be over {{convert|7.6|m|ft}} long by some estimates.<ref name=":1">{{Cite journal|last1=Tapanila|first1=Leif|last2=Pruitt|first2=Jesse|date=2019-09-04|title=Redefining species concepts for the Pennsylvanian scissor tooth shark, Edestus|journal=PLOS ONE|language=en|volume=14|issue=9|article-number=e0220958|doi=10.1371/journal.pone.0220958|issn=1932-6203|pmc=6726245|pmid=31483800|bibcode=2019PLoSO..1420958T|doi-access=free}}</ref><ref name=":2">{{Cite journal |last=Engelman |first=Russell K. |date=2023 |title=A Devonian Fish Tale: A New Method of Body Length Estimation Suggests Much Smaller Sizes for Dunkleosteus terrelli (Placodermi: Arthrodira) |journal=Diversity |language=en |volume=15 |issue=3 |page=318 |doi=10.3390/d15030318 |issn=1424-2818 |doi-access=free }}</ref><ref name=":0">{{Cite journal |last1=Tapanila |first1=Leif |last2=Pruitt |first2=Jesse |last3=Wilga |first3=Cheryl D. |last4=Pradel |first4=Alan |date=2020 |title=Saws, Scissors, and Sharks: Late Paleozoic Experimentation with Symphyseal Dentition |journal=The Anatomical Record |language=en |volume=303 |issue=2 |pages=363–376 |doi=10.1002/ar.24046 |issn=1932-8494 |pmid=30536888 |doi-access=free}}</ref> Eugeneodonts were predatory, with eugeneodontoids likely being generalist feeders and some edestoids being specialized for hunting [[cephalopod]]s.<ref name="Lebedev2009" /><ref name=":3" /><ref name=":0" />

==Taxonomy== [[File:Ornithoprion skeletal.png|thumb|Diagram of ''[[Ornithoprion]],'' a specialised member of [[Caseodontidae]]]]

The list below shows [[taxa]] included within Eugeneodontiformes.<ref>{{cite book |last1=Ginter |first1=M. |last2=Hampe |first2=O. |last3=Duffin |first3=C. |date=2010 |title=Handbook of Paleoichthyology. Volume 3D. Chondrichthyes. Paleozoic Elasmobranchi: Teeth |location=Munich |publisher=Verlag Dr. Friedrich Pfeil |isbn=978-3-89937-116-1}}</ref> *Superfamily Eugeneodontoidei **Family [[Caseodontidae]] ***Genus ''[[Caseodus]]'' ***Genus ''[[Erikodus]]'' ***Genus ''[[Fadenia]]'' ***Genus ''[[Ornithoprion]]'' ***Genus ''[[Pirodus]]'' ***Genus ''[[Romerodus]]'' **Family [[Eugeneodontidae]] ***Genus ''[[Bobbodus]]'' ***Genus ''[[Eugeneodus]]'' ***Genus ''[[Gilliodus]]'' **Family ''[[incertae sedis]]'' ***Genus ''[[Campodus]]'' ***Genus ''[[Chiastodus]]'' ***Genus ''[[Tiaraju]]'' *Superfamily Edestoidea **Family [[Edestidae]] ***Genus ''[[Edestus]]'' ***Genus ''[[Edestodus]]''(?)<ref name="Lebedev2022" /><ref name=":4" /> **Family [[Helicampodontidae]]<ref name="Lebedev2022" /> ***Genus ''[[Helicampodus]]'' ***Genus ''[[Hunanohelicoprion]]'' ***Genus ''[[Parahelicampodus]]'' ***Genus ''[[Sinohelicoprion]]'' **Family [[Helicoprionidae]] ***Genus ''[[Agassizodus]]'' ***Genus ''[[Anisopleurodontis]]''(?)<ref name="da Silva Santos">da Silva Santos, Rubens "Paleoictiofáunula da Formação Pedra de Fogo, Bacia do Parnaiba, NE do Brasil: II. Eugeneodontida-Agassizodontidae." Anais da Academia Brasileira de Ciências 66.4 (1994): 413-424.</ref> ***Genus ''[[Arpagodus]]'' ***Genus ''[[Campyloprion]]'' ***Genus ''[[Helicoprion]]'' ***Genus ''[[Karpinskiprion]]'' ***Genus ''[[Parahelicoprion]]'' ***Genus ''[[Sarcoprion]]'' ***Genus ''[[Toxoprion]]'' **Family Lestrodontidae<ref name=":4">{{Cite journal|last1=Lebedev |first1=O. A. |last2=Itano |first2=W. M. |last3=Duffin |first3=C. J. |last4=Ivanov |first4=A. O. |title=The earliest stem edestoid (Eugeneodontiformes, Chondrichthyes) from the Viséan (lower Carboniferous) of Tula Region, Central Russia, and a revision of Edestoidea |year=2026 |journal=Canadian Journal of Zoology |doi=10.1139/cjz-2025-0140 }}</ref> ***Genus ''[[Lestrodus]]'' ***Genus ''[[Tuyuria]]'' **Family ''[[incertae sedis]]'' ***Genus ''[[Paredestus]]'' ***Genus ''[[Syntomodus]]''(?)<ref name=":4" />

==References== {{Reflist | refs=  <ref name="Tapanila_2013">{{cite journal |author1=Tapanila L. |author2=Pruitt J. |author3=Pradel A. |author4=Wilga C. |author5=Ramsay J. |author6=Schlader R. |author7=Didier D. |title =Jaws for a spiral-tooth whorl: CT images reveal novel adaptation and phylogeny in fossil Helicoprion |journal=Biology Letters |volume =9 |issue =2 |article-number =20130057 |year =2013 |doi =10.1098/rsbl.2013.0057 |pmid=23445952 |pmc=3639784 }}</ref> }}

==External links== *[http://palaeos.com/vertebrates/chondrichthyes/chondrichthyes.html#Eugeneodontida] [[Palaeos]] Vertebrates 70.100 Chondrichthyes: Eugnathostomata at paleos.com *[https://www.jstor.org/pss/1306378 JSTOR: Journal of Paleontology Vol. 70, No. 1 (Jan., 1996), pp. 162–165] *[http://www.devoniantimes.org/who/pages/sharks.html More about Chondrichthyes] {{Webarchive|url=https://web.archive.org/web/20171022144300/http://www.devoniantimes.org/who/pages/sharks.html |date=2017-10-22 }} at Devonian Times

[[Category:Eugeneodontiformes| ]] [[Category:Cisuralian taxonomic orders]] [[Category:Early Triassic extinctions]] [[Category:Early Triassic taxonomic orders]] [[Category:Guadalupian taxonomic orders]] [[Category:Lopingian taxonomic orders]] [[Category:Mississippian first appearances]] [[Category:Mississippian taxonomic orders]] [[Category:Pennsylvanian taxonomic orders]] [[Category:Prehistoric cartilaginous fish orders]] [[Category:Long stubs with short prose]] {{paleo-cartilaginous-fish-stub}}