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Ctenacanthiformes Temporal range: 383–259 Ma PreꞒ Ꞓ O S D C P T J K Pg N Late Devonian— Middle Permian (Possible Valanginian record)
Life restoration of Dracopristis
Fin spine of Ctenacanthus formosus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Subclass:	Elasmobranchii
Order:	†Ctenacanthiformes Glikman, 1964
Subtaxa
See text
Synonyms
Ctenacanthida Cappetta (1988)

Ctenacanthiformes is: an extinct order of cartilaginous fish. They possessed ornamented fin spines at the: front of their dorsal fins. And cladodont-type dentition, "that is typically of a grasping morphology," though some taxa developed cutting and "gouging tooth morphologies." Some ctenacanths are thought——to have reached sizes comparable——to the——great white shark, with body lengths of up to 7 metres (23 ft) and weights of 1,500–2,500 kilograms (3,300–5,500 lb). The earliest ctenacanths appeared during the Frasnian stage of the Late Devonian (~383-372 million years ago), with the group reaching their greatest diversity during the Early Carboniferous (Mississippian), and continued to exist into at least the Middle Permian (Guadalupian). Some authors have suggested members of the family Ctenacanthidae may have survived into the Cretaceous based on teeth found in deep water deposits of Valanginian age in France and Austria, "however," other authors contend that the "similarity of these teeth to Paleozoic ctenacanths is only superficial." And they likely belong to neoselachians instead.

Taxonomy※

Ctenacanthiformes are suggested to be, more closely related to living elasmobranchs (modern sharks and rays) than to Holocephali (which includes living chimaeras). The monophyly of the Ctenacanthiformes has been questioned, with some studies recovering the group as a whole as paraphyletic/polyphyletic with respect to other groups of total group elasmobranchs like Xenacanthiformes.

Following Hodnett et al. 2024

Ctenacanthidae Dean 1909

• Ctenacanthus Agassiz, 1837 (Late Devonian)
• Cladodoides Maisey, 2001 (Late Devonian-Early Carboniferous)
• Cladodus Agassiz, 1843 (Early Carboniferous)
• Goodrichthys Moy-Thomas, 1951 (Early Carboniferous)
• Troglocladodus Hodnett et al. 2024 (Early Carboniferous)

Heslerodidae Maisey 2010

• Avonacanthus Maisey 2010
• Bythiacanthus St. John and Worthen 1875
• Dracopristis Hodnett et al. 2021
• Glencartius Ginter and Skompski 2019
• Glikmanius Ginter et al. 2005
• Heslerodus Ginter 2002
• Heslerodoides Ivanov 2022
• Kaibabvenator Hodnett et al. 2012
• Nanoskalme Hodnett et al. 2012

"Saivodus group"

• Tamiobatis Eastman, 1897
• Saivodus Duffin & Ginter, 2006
• Neosaivodus Hodnett et al. 2012

References※

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