Rhachiosteus
Temporal range: Devonian: Givetian - Frasnian,
Artist's reconstruction of Rhachiosteus (with Trematosteus in the background)
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Placodermi
Order: Arthrodira
Suborder: Brachythoraci
Clade: Eubrachythoraci
Clade: Pachyosteomorphi
Genus: Rhachiosteus
Gross, 1938
Species
  • Rhachiosteus pterygiatus Gross, 1938 (type)

Rhachiosteus is an extinct monospecific genus of arthrodire placoderm from the Middle to Late Devonian of Germany. It is known only from a single specimen, which may be a larval or juvenile form, as the skull of said specimen is only 19 millimetres long.[1]

Phylogeny

Rhachiosteus is a basal member of the clade Pachyosteomorphi, the sister taxon to Coccosteomorphi, which together are the two main sub-clades of Eubrachythoraci. The cladogram below shows the phylogeny of Rhachiosteus:[2]

Eubrachythoraci
Coccosteomorphi
Coccosteoidea
Coccosteidae

Millerosteus minor

Coccosteus cuspidatus

Dickosteus threiplandi

Watsonosteus fletti

Protitanichthys rockportensis

Panxiosteidae

Plourdosteus canadensis

Panxiosteus ocullus

Janiosteus timanicus

Incisoscutoidea

Harrytoombsia elegans

Torosteus tuberculatus

Torosteus pulchellus

Mcnamaraspis kaprios

Compagopiscis croucheri

Trematosteus fontanellus

Camuropiscidae

Incisoscutum ritchiei

Incisoscutum sarahae

Rolfosteus canningensis

Tubonasus lennardensis

Fallacosteus turneri

Camuropiscis laidlawi

Latocamurus coulthardi

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

References

  1. Denison, Robert (1978). Placodermi Volume 2 of Handbook of Paleoichthyology. Stuttgart New York: Gustav Fischer Verlag. p. 128. ISBN 9780895740274.
  2. 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.


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