Opinions from R. H. Denison 1975
- 'Acanthothoraci belongs to Placodermi'
- 'Actinolepidae belongs to Actinolepina'
- 'Actinolepina belongs to Arthrodira'
- 'Antarctaspididae [misspelled as Antarctaspidae] belongs to Antarctaspina'
- 'Antarctaspina belongs to Phyllolepida'
- 'Antiarcha belongs to Placodermi'
- 'Arthrodira belongs to Placodermi'
- 'Asterolepididae [misspelled as Asterolepidae] belongs to Antiarcha'
- 'Asterosteidae belongs to Rhenanida'
- 'Bothriolepididae belongs to Antiarcha'
- 'Brachydeiridae belongs to Brachydeirina'
- 'Brachydeirina belongs to Arthrodira'
- 'Buchanosteidae belongs to Coccosteina'
- 'Bungartiidae belongs to Pachyosteina'
- 'Bungartius belongs to Bungartiidae'
- 'Coccosteida was reranked as the order Coccosteina and belongs to Arthrodira'
- 'Coccosteidae belongs to Coccosteina'
- 'Dinichthyidae belongs to Pachyosteina'
- 'Gemuendenaspidae belongs to Coccosteina'
- 'Heterosteidae [misspelled as Heterostiidae] belongs to Heterostiina'
- 'Heterostiina belongs to Arthrodira'
- 'Holonematidae belongs to Holonematina'
- 'Holonematina belongs to Arthrodira'
- 'Homostiidae belongs to Coccosteina'
- 'Kolymaspidae belongs to Acanthothoraci'
- 'Leiosteidae belongs to Pachyosteina'
- 'Leptosteidae belongs to Brachydeirina'
- 'Macropetalichthyidae belongs to Petalichthyida'
- 'Mylostomatidae belongs to Pachyosteina'
- 'Pachyosteida was reranked as the suborder Pachyosteina and belongs to Arthrodira'
- 'Palaeacanthaspidae belongs to Acanthothoraci'
- 'Paraplesiobatidae belongs to Pseudopetalichthyida'
- 'Petalichthyi is corrected as Petalichthyida and belongs to Placodermi'
- 'Phlyctaeniidae belongs to Phlyctaeniina'
- 'Phlyctaenina [misspelled as Phlyctaeniina] belongs to Arthrodira'
- 'Pholidosteidae belongs to Coccosteina'
- 'Phyllolepida was reranked as a order and belongs to Placodermi'
- 'Phyllolepidae belongs to Phyllolepina'
- 'Phyllolepina belongs to Phyllolepida'
- 'Placodermi belongs to Gnathostomata'
- 'Pseudopetalichthida is corrected as Pseudopetalichthyida and belongs to Placodermi'
- 'Ptyctodontida belongs to Placodermi'
- 'Ptyctodontidae belongs to Ptyctodontida'
- 'Radotinidae belongs to Acanthothoraci'
- 'Rhachiosteidae [misspelled as Rachiosteidae] belongs to Coccosteina'
- 'Rhenanida belongs to Placodermi'
- 'Selenosteidae belongs to Pachyosteina'
- 'Sinolepidae belongs to Antiarcha'
- 'Stensioellida belongs to Placodermi'
- 'Stensioellidae belongs to Stensioellida'
- 'Titanichthyidae belongs to Pachyosteina'
- 'Trematosteidae belongs to Pachyosteina'
- 'Williamsaspidae belongs to Phlyctaeniina'
- 'Wuttagoonaspidae belongs to Wuttagoonaspina'
- 'Wuttagoonaspina belongs to Arthrodira'