Biology:Rhachiosteus

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Short description: Extinct genus of fishes

Rhachiosteus
Temporal range: Devonian: Givetian - Frasnian, 387.7–372.2 Ma
Artist's reconstruction of Rhachiosteus (with Trematosteus in the background)
Scientific classification e
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. pp. 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. 

Wikidata ☰ Q16863336 entry