Synonym: Ptyctodontiformes
Parent taxon: Placodermi according to G. C. Young 2010
See also Denison 1975, Denison 1978, Dineley and Metcalf 1999, Grande and Eastman 1986, Long 2011, Nelson et al. 2016 and Sepkoski 2002
Sister taxa: Acanthothoraci, Acanthothoraciformes, Antiarcha, Arthrodira, Asiacanthus, Austroptyctodus, Bianchengichthys, Brindabellaspida, Campbellodus, Changyonophyton, Coccostei, Coelosteichthys, Deinodus, Entelognathus, Hybosteus, Neopetalichthys, Nessariostoma, Oestophorus, Petalichthida, Petalichthyida, Petalichthyida, Pseudopetalichthyida, Pseudopetalichthyiformes, Ptychostei, Rhenanida, Rhenaniformes, Sedowichthys, Stensioellida, Tollichthys, Wangolepis, Yunnanacanthus
Subtaxa: Denisonodus Ptyctodontidae Rhamphodopsis Tollodus
Ecology: nektonic carnivore
Distribution:
• Carboniferous of the United Kingdom (1 collection)
• Devonian of Australia (1), Belarus (4), Estonia (1), Germany (2), Iran (2), Latvia (2), Poland (1), the Russian Federation (3), South Africa (1), the United Kingdom (3), United States (11: Arizona, Iowa, Michigan, Missouri, Wyoming)
Total: 32 collections including 38 occurrences