Biology:Pachyosteus

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Short description: Genus of fishes (fossil)

Pachyosteus
Temporal range: Late Devonian, 382.7–359.3 Ma
Artist's reconstruction
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: †Placodermi
Order: †Arthrodira
Suborder: †Brachythoraci
Family: †Selenosteidae
Genus: †Pachyosteus
Jaekel, 1903
Species
  • Pachyosteus bulla Jaekel, 1903 (type)
Synonyms
Fossil on display at Geological Museum of the State Geological Institute in Warsaw, Poland

Pachyosteus is an extinct monospecific genus of medium-sized selenosteid arthrodire placoderm known from the Upper Frasnian Kellwasserkalk facies of Late Devonian Bad Wildungen, Germany and from the Famennian portions of the Holy Cross Mountains of Poland .[1] The type species Pachyosteus bulla has a broad skull about 7 to 10 centimetres (3 to 4 in) long, a comparatively long median dorsal plate, and a short rostral plate that meets the pineal plate.

Phylogeny

Pachyosteus 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 Pachyosteus:[2]

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

 
 
 
 
 
 
 
 
 
 
 

In his cladogram, Rücklin (2011) regards Pachyosteus bulla as a basal selenosteid, being the sister taxon of the American genera, and the Kellwasserkalk genera of Germany and Morocco.[3]

Aspinothoracidi
 

Parabelosteus

 
 

Brachydeirus

 
Selenosteidae
 

Pachyosteus

 
 
 
 

Selenosteus

 
 
 

Stenosteus

 
 

Gymnotrachelus

 
 
 
 
 

Microsteus

 
 
 

Walterosteus

 
 
 

Draconichthys

 
 

Enseosteus

 
 
 

Melanosteus

 
 

Rhinosteus

 
 
 
 
 
 
 
 

References

  1. ↑ Denison, Robert (1978). Handbook of Paleoichthyology, Volume 2, Placodermi. New York: Gustav Fischer Verlage. pp. 94. 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. 
  3. ↑ RÜCKLIN, MARTIN (January 14, 2011). "First selenosteid placoderms from the eastern Anti-Atlas of Morocco; osteology, phylogeny and palaeogeographical implications". Palaeontology 56 (1): 25–62. doi:10.1111/j.1475-4983.2010.01026.x. 

Wikidata ☰ Q7122181 entry