Synonym: Arthrodira Woodward 1891
Parent taxon: Placodermi according to J. A. Long 2011
Sister taxa: Acanthothoraciformes, Antiarcha, Antiarchi, Antiarchiformes, Antineosteus, Brindabellaspida, Nessariostoma, Oestophorus, Petalichthida, Petalichthyiformes, Pseudopetalichthyida, Pseudopetalichthys, Ptyctodontiformes, Quasipetalichthyidae, Rhenaniformes, Stensioella, Stensioellida
Subtaxa: Actinolepidae, Actinolepidoidei, Africanaspis, Arctolepidae, Arctonema, Arenipiscis, Aspidichthys, Atlantidosteus, Belemnacanthus, Belosteus, Brachydeirus, Brachyosteus, Brachythoraci, Braunosteus, Bruntonichthys, Buchanosteus, Bullerichthys, Bungartius, Burrinijucosteus, Callognathus, Camuropiscis, Chelyophorus, Coccosteus, Conchopoma, Copanognathus, Cosmacanthus, Cyrtosteus, Deirosteus, Deveonema, Dicksonosteus, Dinomylostoma, Diplognathus, Eldenosteus, Errolosteus, Erromenosteus, Eskimaspis, Euantiarcha, Euarthrodira, Eubrachythoraci, Fallacosteus, Gemuendenaspis, Glyptaspis, Goodradigbeeon, Grazosteus, Groenlandaspis, Gyroplacosteus, Harrytoombsia, Heterosteus, Holdenius, Hollardosteus, Hussakofia, Incisoscutum, Kendrickichthys, Kimberia, Kimberleyichthys, Kueichowlepis, Latocamurus, Laurentaspis, Leptosteus, Machaerognathus, Macropetalichthys, Malerosteus, Mcnamaraspis, Megaloplax, Murmur, Mylostoma, Operchallosteus, Overtonaspis, Oxyosteus, Parabelosteus, Parabuchanosteus, Paramylostoma, Phlyctaenaspis, Pholidosteus, Phylctaeniida, Phyllolepida, Platyaspis, Plourdosteus, Prescottaspis, Qataraspis, Rachiosteus, Rhenonema, Rolfosteus, Selenosteidae, Squamatognathus, Stuertzaspis, Synauchenia, Taemasosteus, Tafilalichthys, Tapinosteus, Taunaspis, Tiaraspis, Timanosteus, Titanichthys, Toombsosteus, Torosteus, Trachosteus, Trematosteus, Tropidosteus, Tubonasus, Wheathillaspis, Williamsaspis, Wuttagoonaspina, Yinosteus
Ecology: nektonic carnivore