Panxiosteidae

{{automatic taxobox

| fossil_range = Devonian: Givetian to Early Frasnian, ~{{Fossil range|387.7|382.7}}

| image = Plourdosteus speciesDB15 2.jpg

| image_caption = Various species of Plourdosteus

| display_parents = 4

| taxon = Panxiosteidae

| authority = Wang, 1979

| subdivision_ranks = Genera

| subdivision =

}}

Panxiosteidae is an extinct family of arthrodire placoderms that lived during the Devonian period.

Phylogeny

The family Panxiosteidae was erected by Wang in 1979. Members of the family are noted for showing morphologically intermediate traits between coccosteids and dunkleosteids.{{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 }} In the 2010 Carr & Hlavin phylogenetic study, Panxiosteidae was recognized as the sister taxon to the family Dunkleosteidae, which together comprised the superfamily Dunkleosteoidea (one of the three major clades of Eubrachythoraci).{{Cite journal |last1=Carr |first1=R.K. |last2=Hlavin |first2=W.J. |title=Two new species of Dunkleosteus Lehman, 1956, from the Ohio Shale Formation (USA, Famennian) and the Kettle Point Formation (Canada, Upper Devonian), and a cladistic analysis of the Eubrachythoraci (Placodermi, Arthrodira) |journal=Zoological Journal of the Linnean Society |volume=159 |issue=1 |pages=195-222 |year=2010 |doi=10.1111/j.1096-3642.2009.00578.x |doi-access=free }}

The phylogeny of Panxiosteidae from the 2013 Zhu & Zhu study is shown in the cladogram below:{{Cite journal |author1=You-An Zhu |author2=Min Zhu |title=A redescription of Kiangyousteus yohii (Arthrodira: Eubrachythoraci) from the Middle Devonian of China, with remarks on the systematics of the Eubrachythoraci | journal=Zoological Journal of the Linnean Society |volume=169 |issue=4 |pages=798-819 |year=2013 |doi=10.1111/zoj12089 |doi-access= }}

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

|grouplabel1={{clade labels |width=10em; |label1=Pachyosteomorphi |top1=65% |color1=green}}

|label1=Eubrachythoraci

|1={{clade

|label1=Coccosteomorphi

|1={{clade

|1=Coccosteus cuspidatus

|2={{clade

|1=Harrytoombsia elegans

|2={{clade

|1=Mcnamaraspis kaprios

|label2=Incisoscutoidea

|2={{clade

|1=Compagopiscis croucheri

|2={{clade

|1=Incisoscutum ritchiei

|2=Incisoscutum sarahae }}

|label3=Camuropiscidae

|3={{clade

|1=Latocamurus coulthardi

|2=Camuropiscis laidlawi

|3={{clade

|1=Rolfosteus canningensis

|2=Tubonasus lennardensis

|3=Fallacosteus turneri }} }} }} }} }} }}

|label2=Aspinothoracidi

|2={{clade

|1=Dinichthys herzeri |barbegin1=green

|2={{clade

|1=Hadrosteus rapax |bar1=green

|2={{clade

|1=Gorgonichthys clarki |bar1=green

|2={{clade

|1=Heintzichthys gouldii |bar1=green

|label2=Selenosteidae

|2={{clade

|1=Stenosteus angustopectus |bar1=green

|2={{clade

|1=Gymnotrachelus hydei |bar1=green

|2={{clade

|1=Rhinosteus parvulus |bar1=green

|2=Pachyosteus bulla |bar2=green }} }} }} }} }} }} }} }}

|label2=Dunkleosteoidea

|2={{clade

|1=Westralichthys uwagedensis |bar1=green

|2={{clade

|1={{clade

|1=Protitanichthys rockportensis |bar1=green

|label2=Panxiosteidae

|2={{clade

|1=Panxiosteus ocullus |bar1=green

|2=Janiosteus timanicus |bar2=green

|3=Plourdosteus canadensis |bar3=green }} }}

|label2=Dunkleosteidae

|2={{clade

|1={{clade

|1=Eastmanosteus calliaspis |bar1=green

|2=Xiangshuiosteus wui |bar2=green }}

|2={{clade

|1=Eastmanosteus pustulosus |bar1=green

|2=Kiangyousteus yohii |bar2=green

|3=Golshanichthys asiatica |bar3=green

|4={{clade

|1=Dunkleosteus amblyodoratus |bar1=green

|2=Dunkleosteus terrelli |bar2=green

|3=Dunkleosteus raveri |barend3=green }} }} }} }} }} }} }}

However, the subsequent 2016 Zhu et al. study using a larger morphological dataset recovered Panxiosteidae well outside of Dunkleosteoidea, instead within Coccosteomorphi and then Coccosteoidea as the sister group of Coccosteidae, as shown in the cladogram below:

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

|label1=Eubrachythoraci

|1={{clade

|label1=Coccosteomorphi

|1={{clade

|label1=Coccosteoidea

|1={{clade

|label1=Coccosteidae

|1={{clade

|1=Millerosteus minor

|2=Coccosteus cuspidatus }}

|2={{clade