Gymnotrachelus

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]

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
Kingdom:	Animalia
Phylum:	Chordata
Class:	†Placodermi
Order:	†Arthrodira
Suborder:	†Brachythoraci
Family:	†Selenosteidae
Genus:	†Gymnotrachelus Dunkel & Bungart, 1939
Species
Gymnotrachelus hydei Dunkle & Bungart, 1939 (type)

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