Gymnotrachelus

Gymnotrachelus Temporal range: Late Devonian: Famennian, 371.1–359.3 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Artist's reconstruction
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	†Placodermi
Order:	†Arthrodira
Suborder:	†Brachythoraci
Family:	†Selenosteidae
Genus:	†Gymnotrachelus Dunkel & Bungart, 1939
Species
Gymnotrachelus hydei Dunkle & Bungart, 1939 (type)

Gymnotrachelus is an extinct monospecific genus of large selenosteid arthrodire placoderm of the Late Devonian known from the Late Famennian Cleveland Shale of Ohio.[1] The type species is Gymnotrachelus hydei.[2]

Phylogeny

Gymnotrachelus is a member of the family Selenosteidae of the clade Aspinothoracidi, which belongs to the clade Pachyosteomorphi, one of the two major clades within Eubrachythoraci. The cladogram below shows the phylogeny of Gymnotrachelus:[3]

Eubrachythoraci

Coccosteomorphi  Pachyosteomorphi  Rhachiosteus pterygiatus Dunkleosteoidea  Eastmanosteus calliaspis Eastmanosteus pustulosus Kiangyousteus yohii Golshanichthys asiatica Westralichthys uwagedensis Dunkleosteus raveri Dunkleosteus terrelli Dunkleosteus amblyodoratus  Heterostiidae  Heterosteus ingens Yinosteus major Aspinothoracidi Tapinosteus heintzi Bullerichthys fascidens Kendrickichthys cavernosus Bruntonichthys multidens Dinichthys herzeri Hadrosteus rapax Gorgonichthys clarki  Selenosteidae  Heintzichthys gouldii Pachyosteus bulla Gymnotrachelus hydei Stenosteus angustopectus Brachyosteus dietrichi Melanosteus occitanus Rhinosteus parvulus

According to a 2022 Jobbins et al. study, Gymnotrachelus was found to be an outgroup to Heintzichthys and Gorgonichthys.[4]

	Gymnotrachelus
	Gorgonichthys Heintzichthys

References

1. Denison, Robert (1978). Handbook of Paleoichthyology, Volume 2, Placodermi. New York: Gustav Fischer Verlage. p. 96. ISBN 9780895740274.
2. Carr, Robert (1994). "A redescription of Gymnotrachelus hydei (Placodermi : Arthrodira) from the Cleveland Shale (Famennian) of north2 ern Ohio, U. S. A." (PDF). Kirtlandia (48): 3–21.
3. Zhu, You-An; Zhu, Min; Wang, Jun-Qing (1 April 2016). "Redescription of Yinostius major (Arthrodira: Heterostiidae) from the Lower Devonian of China, and the interrelationships of Brachythoraci". Zoological Journal of the Linnean Society. 176 (4): 806–834. doi:10.1111/zoj.12356. ISSN 0024-4082.
4. Jobbins, Melina; Rücklin, Martin; Ferrón, Humberto G.; Klug, Christian (2022). "A new selenosteid placoderm from the Late Devonian of the eastern Anti-Atlas (Morocco) with preserved body outline and its ecomorphology". Frontiers in Ecology and Evolution. 10. doi:10.3389/fevo.2022.969158. hdl:10550/85583. ISSN 2296-701X.