# Eugeneodontiformes

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Extinct group of cartilaginous fishes

Eugeneodontiformes Temporal range: 330.9–247.2 Ma PreꞒ Ꞓ O S D C P T J K Pg N Early Carboniferous (Serpukhovian) to Early Triassic (Olenekian) Body fossil of Romerodus orodontus, a caseodont Jaw cartilage and teeth of Edestus (or Edestodus) minor, an edestoid Scientific classification Kingdom: Animalia Phylum: Chordata Class: Chondrichthyes Subclass: Holocephali Order: †Eugeneodontiformes Zangerl, 1981 Families See text Synonyms Eugeneodontida

Tooth whorl of *[Helicoprion bessonowi](/source/Helicoprion_bessonovi)*, which in life was positioned in the lower jaw

**Eugeneodontiformes** (also called **Eugeneodontida**) is an [extinct](/source/Extinct) and poorly known [order](/source/Order_(biology)) of [cartilaginous fishes](/source/Chondrichthyes). They possessed "tooth-whorls" on the [symphysis](/source/Symphysis) of either the lower or both jaws, and pectoral fins supported by long [radials](/source/Fish_fin). They probably lacked [pelvic fins](/source/Pelvic_fin) and anal fins.[1] The [palatoquadrate](/source/Palatoquadrate) was either fused to the skull or reduced in various members of the group. They are now determined to be within the [Holocephali](/source/Holocephali); their closest living relatives are [chimaeras](/source/Chimaera).[2] The eugeneodonts are named after paleontologist [Eugene S. Richardson, Jr.](https://en.wikipedia.org/w/index.php?title=Eugene_S._Richardson,_Jr.&action=edit&redlink=1)[3] The group first appeared in the fossil record during the late [Mississippian](/source/Mississippian_(geology)) ([Serpukhovian](/source/Serpukhovian)),[4] and the last eugeneodonts are known from the [Early Triassic](/source/Early_Triassic) ([Olenekian](/source/Olenekian)).[5]

Members of the Eugeneodontiformes are further classified into two superfamilies and either four, five or six different families. The [Helicoprionidae](/source/Helicoprionidae) (or Agassizodontidae) and [Edestidae](/source/Edestidae) are assigned to the superfamily **Edestoidea**, the former containing genera such as *[Helicoprion](/source/Helicoprion)* and *[Parahelicoprion](/source/Parahelicoprion)*, and the latter containing genera such as *[Edestus](/source/Edestus)*. The family **Helicampodontidae** has been used for genera that do not closely resemble typical members of either of these two groups,[6] and the family **Lestrodontidae** has been proposed for the genus *[Lestrodus](/source/Lestrodus)*.[7] The superfamily **Eugeneodontoidei** (traditionally **Caseodontoidea**)[8] includes the families [Caseodontidae](/source/Caseodontidae) and [Eugeneodontidae](/source/Eugeneodontidae), which were smaller and less-specialized than the edestoids.[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.[9] The [Late Carboniferous](/source/Late_Carboniferous) *[Edestus](/source/Edestus)* has been estimated to reach exceed 6.7 metres (22 ft) in length, with some [Early Permian](/source/Early_Permian) *[Helicoprion](/source/Helicoprion)* suggested to be over 7.6 metres (25 ft) long by some estimates.[10][11][12] Eugeneodonts were predatory, with eugeneodontoids likely being generalist feeders and some edestoids being specialized for hunting [cephalopods](/source/Cephalopod).[1][3][12]

## Taxonomy

Diagram of *[Ornithoprion](/source/Ornithoprion),* a specialised member of [Caseodontidae](/source/Caseodontidae)

The list below shows [taxa](/source/Taxa) included within Eugeneodontiformes.[13]

- Superfamily Eugeneodontoidei - Family [Caseodontidae](/source/Caseodontidae) - Genus *[Caseodus](/source/Caseodus)* - Genus *[Erikodus](/source/Erikodus)* - Genus *[Fadenia](/source/Fadenia)* - Genus *[Ornithoprion](/source/Ornithoprion)* - Genus *[Pirodus](/source/Pirodus)* - Genus *[Romerodus](/source/Romerodus)* - Family [Eugeneodontidae](/source/Eugeneodontidae) - Genus *[Bobbodus](/source/Bobbodus)* - Genus *[Eugeneodus](/source/Eugeneodus)* - Genus *[Gilliodus](/source/Gilliodus)* - Family *[incertae sedis](/source/Incertae_sedis)* - Genus *[Campodus](/source/Campodus)* - Genus *[Chiastodus](https://en.wikipedia.org/w/index.php?title=Chiastodus&action=edit&redlink=1)* - Genus *[Tiaraju](https://en.wikipedia.org/w/index.php?title=Tiaraju&action=edit&redlink=1)*

- Superfamily Edestoidea - Family [Edestidae](/source/Edestidae) - Genus *[Edestus](/source/Edestus)* - Genus *[Edestodus](https://en.wikipedia.org/w/index.php?title=Edestodus&action=edit&redlink=1)*(?)[6][14] - Family [Helicampodontidae](/source/Helicampodontidae)[6] - Genus *[Helicampodus](/source/Helicampodus)* - Genus *[Hunanohelicoprion](https://en.wikipedia.org/w/index.php?title=Hunanohelicoprion&action=edit&redlink=1)* - Genus *[Parahelicampodus](/source/Parahelicampodus)* - Genus *[Sinohelicoprion](/source/Sinohelicoprion)* - Family [Helicoprionidae](/source/Helicoprionidae) - Genus *[Agassizodus](/source/Agassizodus)* - Genus *[Anisopleurodontis](/source/Anisopleurodontis)*(?)[15] - Genus *[Arpagodus](/source/Arpagodus)* - Genus *[Campyloprion](/source/Campyloprion)* - Genus *[Helicoprion](/source/Helicoprion)* - Genus *[Karpinskiprion](/source/Karpinskiprion)* - Genus *[Parahelicoprion](/source/Parahelicoprion)* - Genus *[Sarcoprion](/source/Sarcoprion)* - Genus *[Toxoprion](/source/Toxoprion)* - Family Lestrodontidae[14] - Genus *[Lestrodus](/source/Lestrodus)* - Genus *[Tuyuria](https://en.wikipedia.org/w/index.php?title=Tuyuria&action=edit&redlink=1)* - Family *[incertae sedis](/source/Incertae_sedis)* - Genus *[Paredestus](/source/Paredestus)* - Genus *[Syntomodus](/source/Syntomodus)*(?)[14]

## References

1. ^ [***a***](#cite_ref-Lebedev2009_1-0) [***b***](#cite_ref-Lebedev2009_1-1) Lebedev, O.A. (2009). ["A new specimen of *Helicoprion* Karpinsky, 1899 from Kazakhstanian Cisurals and a new reconstruction of its tooth whorl position and function"](https://www.researchgate.net/publication/249440368). *Acta Zoologica*. **90**: 171–182. [doi](/source/Doi_(identifier)):[10.1111/j.1463-6395.2008.00353.x](https://doi.org/10.1111%2Fj.1463-6395.2008.00353.x). [ISSN](/source/ISSN_(identifier)) [0001-7272](https://search.worldcat.org/issn/0001-7272).

1. **[^](#cite_ref-Tapanila_2013_2-0)** Tapanila L.; Pruitt J.; Pradel A.; Wilga C.; Ramsay J.; Schlader R.; Didier D. (2013). ["Jaws for a spiral-tooth whorl: CT images reveal novel adaptation and phylogeny in fossil Helicoprion"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3639784). *Biology Letters*. **9** (2) 20130057. [doi](/source/Doi_(identifier)):[10.1098/rsbl.2013.0057](https://doi.org/10.1098%2Frsbl.2013.0057). [PMC](/source/PMC_(identifier)) [3639784](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3639784). [PMID](/source/PMID_(identifier)) [23445952](https://pubmed.ncbi.nlm.nih.gov/23445952).

1. ^ [***a***](#cite_ref-:3_3-0) [***b***](#cite_ref-:3_3-1) [***c***](#cite_ref-:3_3-2) Zangerl, R. (1981). *Handbook of Paleoichthyology. Volume 3A. Chondrichthyes I. Paleozoic Elasmobranchi*. Stuttgart: Gustav Fischer Verlag. [ISBN](/source/ISBN_(identifier)) [978-3-89937-045-4](https://en.wikipedia.org/wiki/Special:BookSources/978-3-89937-045-4).

1. **[^](#cite_ref-4)** Hodnett, John-Paul M.; Elliott, David K. (December 2018). ["Carboniferous chondrichthyan assemblages from the Surprise Canyon and Watahomigi formations (latest Mississippian–Early Pennsylvanian) of the western Grand Canyon, Northern Arizona"](https://www.cambridge.org/core/product/identifier/S0022336018000720/type/journal_article). *Journal of Paleontology*. **92** (S77): 1–33. [doi](/source/Doi_(identifier)):[10.1017/jpa.2018.72](https://doi.org/10.1017%2Fjpa.2018.72). [ISSN](/source/ISSN_(identifier)) [0022-3360](https://search.worldcat.org/issn/0022-3360).

1. **[^](#cite_ref-Scheyer_et_al_2014_5-0)** Scheyer, Torsten M.; Romano, Carlo; Jenks, Jim; Bucher, Hugo (19 March 2014). ["Early Triassic Marine Biotic Recovery: The Predators' Perspective"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3960099). *PLOS ONE*. **9** (3) e88987. [Bibcode](/source/Bibcode_(identifier)):[2014PLoSO...988987S](https://ui.adsabs.harvard.edu/abs/2014PLoSO...988987S). [doi](/source/Doi_(identifier)):[10.1371/journal.pone.0088987](https://doi.org/10.1371%2Fjournal.pone.0088987). [PMC](/source/PMC_(identifier)) [3960099](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3960099). [PMID](/source/PMID_(identifier)) [24647136](https://pubmed.ncbi.nlm.nih.gov/24647136).

1. ^ [***a***](#cite_ref-Lebedev2022_6-0) [***b***](#cite_ref-Lebedev2022_6-1) [***c***](#cite_ref-Lebedev2022_6-2) Lebedev, O. A.; Itano, W. M.; Johanson, Z.; Alekseev, A. S.; Smith, M. M.; Ivanov, A. V.; Novikov, I. V. (2022). "Tooth whorl structure, growth and function in a helicoprionid chondrichthyan Karpinskiprion (nom. nov.) (Eugeneodontiformes) with a revision of the family composition". *Earth and Environmental Science Transactions of the Royal Society of Edinburgh*. **113** (4): 337–360. [doi](/source/Doi_(identifier)):[10.1017/S1755691022000251](https://doi.org/10.1017%2FS1755691022000251).

1. **[^](#cite_ref-7)** Lebedev, Oleg A.; Itano, Wayne M.; Duffin, Christopher J.; Ivanov, Alexander O. (2026). ["The earliest stem edestoid (Eugeneodontiformes, Chondrichthyes) from the Viséan (lower Carboniferous) of Tula Region, Central Russia, and a revision of Edestoidea"](https://cdnsciencepub.com/doi/10.1139/cjz-2025-0140). *Canadian Journal of Zoology*. **104**: 1–24. [doi](/source/Doi_(identifier)):[10.1139/cjz-2025-0140](https://doi.org/10.1139%2Fcjz-2025-0140). [ISSN](/source/ISSN_(identifier)) [0008-4301](https://search.worldcat.org/issn/0008-4301).

1. **[^](#cite_ref-8)** Van der Laan, Richard (2018-10-11). ["Family-group names of fossil fishes"](http://www.europeanjournaloftaxonomy.eu/index.php/ejt/article/view/597). *European Journal of Taxonomy* (466). [doi](/source/Doi_(identifier)):[10.5852/ejt.2018.466](https://doi.org/10.5852%2Fejt.2018.466). [ISSN](/source/ISSN_(identifier)) [2118-9773](https://search.worldcat.org/issn/2118-9773).

1. **[^](#cite_ref-9)** Gayford, Joel H.; Engelman, Russell K.; Sternes, Phillip C.; Itano, Wayne M.; Bazzi, Mohamad; Collareta, Alberto; Salas‐Gismondi, Rodolfo; Shimada, Kenshu (2024). ["Cautionary tales on the use of proxies to estimate body size and form of extinct animals"](https://onlinelibrary.wiley.com/doi/10.1002/ece3.70218). *Ecology and Evolution*. **14** (9). [doi](/source/Doi_(identifier)):[10.1002/ece3.70218](https://doi.org/10.1002%2Fece3.70218). [ISSN](/source/ISSN_(identifier)) [2045-7758](https://search.worldcat.org/issn/2045-7758). [PMC](/source/PMC_(identifier)) [11368419](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11368419). [PMID](/source/PMID_(identifier)) [39224151](https://pubmed.ncbi.nlm.nih.gov/39224151).

1. **[^](#cite_ref-:1_10-0)** Tapanila, Leif; Pruitt, Jesse (2019-09-04). ["Redefining species concepts for the Pennsylvanian scissor tooth shark, Edestus"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6726245). *PLOS ONE*. **14** (9) e0220958. [Bibcode](/source/Bibcode_(identifier)):[2019PLoSO..1420958T](https://ui.adsabs.harvard.edu/abs/2019PLoSO..1420958T). [doi](/source/Doi_(identifier)):[10.1371/journal.pone.0220958](https://doi.org/10.1371%2Fjournal.pone.0220958). [ISSN](/source/ISSN_(identifier)) [1932-6203](https://search.worldcat.org/issn/1932-6203). [PMC](/source/PMC_(identifier)) [6726245](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6726245). [PMID](/source/PMID_(identifier)) [31483800](https://pubmed.ncbi.nlm.nih.gov/31483800).

1. **[^](#cite_ref-:2_11-0)** Engelman, Russell K. (2023). ["A Devonian Fish Tale: A New Method of Body Length Estimation Suggests Much Smaller Sizes for Dunkleosteus terrelli (Placodermi: Arthrodira)"](https://doi.org/10.3390%2Fd15030318). *Diversity*. **15** (3): 318. [doi](/source/Doi_(identifier)):[10.3390/d15030318](https://doi.org/10.3390%2Fd15030318). [ISSN](/source/ISSN_(identifier)) [1424-2818](https://search.worldcat.org/issn/1424-2818).

1. ^ [***a***](#cite_ref-:0_12-0) [***b***](#cite_ref-:0_12-1) Tapanila, Leif; Pruitt, Jesse; Wilga, Cheryl D.; Pradel, Alan (2020). ["Saws, Scissors, and Sharks: Late Paleozoic Experimentation with Symphyseal Dentition"](https://doi.org/10.1002%2Far.24046). *The Anatomical Record*. **303** (2): 363–376. [doi](/source/Doi_(identifier)):[10.1002/ar.24046](https://doi.org/10.1002%2Far.24046). [ISSN](/source/ISSN_(identifier)) [1932-8494](https://search.worldcat.org/issn/1932-8494). [PMID](/source/PMID_(identifier)) [30536888](https://pubmed.ncbi.nlm.nih.gov/30536888).

1. **[^](#cite_ref-13)** Ginter, M.; Hampe, O.; Duffin, C. (2010). *Handbook of Paleoichthyology. Volume 3D. Chondrichthyes. Paleozoic Elasmobranchi: Teeth*. Munich: Verlag Dr. Friedrich Pfeil. [ISBN](/source/ISBN_(identifier)) [978-3-89937-116-1](https://en.wikipedia.org/wiki/Special:BookSources/978-3-89937-116-1).

1. ^ [***a***](#cite_ref-:4_14-0) [***b***](#cite_ref-:4_14-1) [***c***](#cite_ref-:4_14-2) Lebedev, O. A.; Itano, W. M.; Duffin, C. J.; Ivanov, A. O. (2026). "The earliest stem edestoid (Eugeneodontiformes, Chondrichthyes) from the Viséan (lower Carboniferous) of Tula Region, Central Russia, and a revision of Edestoidea". *Canadian Journal of Zoology*. [doi](/source/Doi_(identifier)):[10.1139/cjz-2025-0140](https://doi.org/10.1139%2Fcjz-2025-0140).

1. **[^](#cite_ref-da_Silva_Santos_15-0)** 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.

## External links

- [\[1\]](http://palaeos.com/vertebrates/chondrichthyes/chondrichthyes.html#Eugeneodontida) [Palaeos](/source/Palaeos) Vertebrates 70.100 Chondrichthyes: Eugnathostomata at paleos.com

- [JSTOR: Journal of Paleontology Vol. 70, No. 1 (Jan., 1996), pp. 162–165](https://www.jstor.org/pss/1306378)

- [More about Chondrichthyes](http://www.devoniantimes.org/who/pages/sharks.html) [Archived](https://web.archive.org/web/20171022144300/http://www.devoniantimes.org/who/pages/sharks.html) 2017-10-22 at the [Wayback Machine](/source/Wayback_Machine) at Devonian Times

v t e Genera of Holocephali Kingdom: Animalia Phylum: Chordata Class: Chondrichthyes Gnathostomata see Gnathostomata Chondrichthyes see Chondrichthyes Holocephali see below↓ Holocephali †Iniopterygiformes "Iniopterygidae" Cervifurca Iniopteryx Papilionichthys Promexyele Rainerichthys Sibyrhynchidae Iniopera Inioxyele Sibyrhynchus †"Orodontiformes" Orodus Leiodontidae Cristatodens Leiodus †Eugeneodontiformes Anisopleurodontis Arpagodus Campodus Campyloprion Paredestus Caseodontidae Caseodus Erikodus Fadenia Ornithoprion Pirodus Romerodus Eugeneodontidae Bobbodus Eugeneodus Gilliodus Edestidae Edestus Lestrodus Syntomodus? Helicampodontidae Helicampodus Hunanohelicoprion Parahelicampodus Sinohelicoprion Helicoprionidae Agassizodus Helicoprion Karpinskiprion Parahelicoprion Sarcoprion Shaktauites Toxoprion †Itapyrodidae Fairchildodus Itapyrodus †Pristodontidae Megactenopetalus Peripristis Pristodus †Petalodontiformes sensu stricto Belantsea Calopodus? Ctenoptychius Davodus? Fissodus Glyphanodus? Peltodus Petalorhynchus Siksika Janassidae Batillodus? Cavusodus Cholodus Cypripediodens Janassa Strigilodus? Obruchevodidae Clavusodens Fissodopsis Netsepoye Obruchevodus Petalodontidae Antliodus Petalodus Polyrhizodus †"Paraselachii" Debeeriidae Debeerius Heteropetalus Gregoriidae Bealbonn Gregorius Srianta †Copodontidae Acmoniodus Copodus Melanodus Synthetodus †Psammodontidae Lagarodus? Psammodus †"Cochliodontiformes" Arcuodus Solenodus? Psephodontidae Kanodus Psephodus Cochliodontidae Cochliodus Deltodus Lophodus? Sandalodus Thoralodus Venustodus? †Chondrenchelyiformes Chondrenchelys Harpagofututor Platyxystrodus? Solenodus? †Listracanthidae? Acanthorhachis Listracanthus †Menaspiformes Deltoptychius Menaspis Traquairius †Incertae sedis Chomatodus Climaxodus Cromhallia Delphyodontos? Desmiodus Gondwanodus Harpacanthus Harpacodus Helodus Jimpohlia Lisgodus Macadens Polysentor Rotuladens Tanaodus Chimaeriformes Echinochimaera? Protochimaera? Similihariotta? †Squalorajoidei Squaloraja Sulcacanthus? †Myriacanthidae Acanthorhina Agkistracanthus Alethodontus Chimaeropsis Halonodon Metopacanthus Myriacanthus Oblidens Recurvacanthus Chimaeroidei (Modern chimaeras) Callorhinchidae †Bathytheristes †Brachymylus Callorhinchus †Darbasodus †Edaphodon †Eomanodon? †Eumylodus †Ganodus? †Ischyodus †Leptomylus †Ptyktoptychion Chimaeridae †Belgorodon †Canadodus Chimaera Hydrolagus Rhinochimaeridae †Amylodon †Elasmodectes? †Elasmodus Harriotta †Lebediodon Neoharriotta †Psaliodus Rhinochimaera †Stolidon Category Commons

v t e Evolution of fish Fish Timeline of fish evolution Forerunners Basal member †Pikaia Cephalochordate †Cathaymyrus Lancelet Olfactores †Haikouella Tunicate †Myllokunmingiidae? (†Haikouichthys, †Myllokunmingia) †Zhongxiniscus? Jawless fish Cyclostomata Hagfish Hyperoartia Lamprey †Conodonts †Protoconodonta? †Paraconodontida †Conodonta †Ostracoderms †Pteraspidomorphi †Thelodonti †Anaspida †Cephalaspidomorphi †Galeaspida †Pituriaspida †Osteostraci Jawed fish †Placoderms †Antiarchi †Arthrodira †Brindabellaspida †Petalichthyida †Phyllolepida †Ptyctodontida †Rhenanida †Acanthothoraci †Pseudopetalichthyida? †Stensioellida? †Acanthodii †Acanthodiformes †"Climatiiformes" †Diplacanthiformes †Ischnacanthiformes Cartilaginous Elasmobranchii †Ctenacanthiformes †Hybodontiformes †Phoebodontiformes †Xenacanthida Ray Shark Holocephali †Eugeneodontida †Iniopterygiformes †Petalodontiformes †Symmoriiformes Chimaera Bony Lobe-finned †Onychodontiformes Coelacanth Rhipidistia †Porolepiformes Lungfish Tetrapodomorpha Ray-finned †"Palaeonisciformes" Cladistia Polypteriformes Chondrostei Acipenseriformes Neopterygii †Pycnodontiformes Halecomorphi Ginglymodi Teleost Lists Lists of prehistoric fish spiny sharks placoderms cartilaginous bony lobe-finned List of transitional fossils Related Prehistoric life Transitional fossils Vertebrate paleontology † extinct

Taxon identifiers Eugeneodontida Wikidata: Q139006 Wikispecies: Eugeneodontida EoL: 60399457 Paleobiology Database: 34445 Paleobiology Database: 149812 Taxonomicon: 70786 Eugeneodontiformes Wikidata: Q25803969 Wikispecies: Eugeneodontiformes EoL: 42348554 IRMNG: 11432 Paleobiology Database: 34445 Taxonomicon: 201739

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