Pachyosteus

{{Automatic taxobox

| fossil_range = Late Devonian, {{Fossil range|382.7|359.3}}

| image = Pachyosteus bulla reconstruction.jpg

| image_caption = Artist's reconstruction

| taxon = Pachyosteus

| authority = Jaekel, 1903

| subdivision_ranks = Species

| subdivision =

Pachyosteus bulla Jaekel, 1903 (type)

| synonyms =

Pachyosteus grossi Stensiö 1959

}}

File:Pachyosteus bulla.jpg 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.{{cite book|last=Denison|first=Robert|title=Handbook of Paleoichthyology, Volume 2, Placodermi|year=1978|publisher=Gustav Fischer Verlage|location=New York|isbn=9780895740274|pages=94}} The type species Pachyosteus bulla has a broad skull about {{convert|7|to|10|cm|in|0}} 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:{{Cite journal |last1=Zhu |first1=You-An |last2=Zhu |first2=Min |last3=Wang |first3=Jun-Qing |date=1 April 2016 |title=Redescription of Yinostius major (Arthrodira: Heterostiidae) from the Lower Devonian of China, and the interrelationships of Brachythoraci |journal=Zoological Journal of the Linnean Society |volume=176 |issue=4 |pages=806–834 |doi=10.1111/zoj.12356|issn=0024-4082 |doi-access=free }}

{{clade| style=font-size:85%;line-height:85%

|label1=Eubrachythoraci

|1={{clade

|1=Coccosteomorphi

|label2=Pachyosteomorphi

|2={{clade

|1=Rhachiosteus pterygiatus

|2={{clade

|label1=Dunkleosteoidea

|1={{clade

|1=Eastmanosteus calliaspis

|2={{clade

|1={{clade

|1=Eastmanosteus pustulosus

|2=Kiangyousteus yohii }}

|2={{clade

|1=Golshanichthys asiatica

|2={{clade

|1=Westralichthys uwagedensis

|2={{clade

|1={{clade

|1=Dunkleosteus raveri

|2=Dunkleosteus terrelli }}

|2={{clade

|1=Dunkleosteus amblyodoratus

|label2=Heterostiidae

|2={{clade

|1=Heterosteus ingens

|2=Yinosteus major }} }} }} }} }} }} }}

|label2=Aspinothoracidi

|2={{clade

|1=Tapinosteus heintzi

|2={{clade

|1={{clade

|1=Bullerichthys fascidens

|2={{clade

|1=Kendrickichthys cavernosus

|2=Bruntonichthys multidens }} }}

|2={{clade

|1=Dinichthys herzeri

|2={{clade

|1=Hadrosteus rapax

|2={{clade| style=font-size:110%;line-height:95%

|1=Gorgonichthys clarki

|label2=Selenosteidae

|2={{clade

|1=Heintzichthys gouldii

|2=Pachyosteus bulla

|3=Gymnotrachelus hydei

|4=Stenosteus angustopectus

|5=Brachyosteus dietrichi

|6={{clade

|1=Melanosteus occitanus

|2=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.{{cite journal|last=RÜCKLIN|first=MARTIN|title=First selenosteid placoderms from the eastern Anti-Atlas of Morocco; osteology, phylogeny and palaeogeographical implications|journal=Palaeontology|date=January 14, 2011|volume=56|issue=1|pages=25–62|doi=10.1111/j.1475-4983.2010.01026.x}}

{{clade| style=font-size:100%;line-height:85%

|label1=Aspinothoracidi

|1={{clade

|1=Parabelosteus

|2=Brachydeirus

|label3=Selenosteidae

|3={{clade

|1=Pachyosteus

|2={{clade

|1={{clade

|1=Selenosteus

|2={{clade