Panxiosteus Explained

Panxiosteus is an extinct monospecific genus of placoderm arthrodire from the Middle Devonian: Givetian stage of Yunnan province, China.

Phylogeny

Panxiosteus is a member of Panxiosteidae. 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).^[1] The phylogeny of Panxiosteus within Panxiosteidae is shown in the cladogram below from the 2013 Zhu & Zhu study:^[2]

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:^[3]

Notes and References

1. Carr . R.K. . Hlavin . W.J. . 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) . . 159 . 1 . 195-222 . 2010 . 10.1111/j.1096-3642.2009.00578.x . free .
2. You-An Zhu . Min Zhu . A redescription of Kiangyousteus yohii (Arthrodira: Eubrachythoraci) from the Middle Devonian of China, with remarks on the systematics of the Eubrachythoraci . . 169 . 4 . 798-819 . 2013 . 10.1111/zoj12089 .
3. 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 . . 176 . 4 . 806–834 . 10.1111/zoj.12356. 0024-4082 . free .