Diplacanthiformes (also known as Diplacanthida, Diplacanthoidei, or Diplacanthini) is an order of "acanthodian" stem-chondrichthyans which lived during the Devonian Period.[1] 
 Subtaxa
 - incertae sedis 
- Genus Bryantonchus
  - Genus Culmacanthus
  - Genus Devononchus
  - Genus Striacanthus
  - Genus Tetanopsyrus
 
  - Family Diplacanthidae 
  - Family Gladiobranchidae? 
- Genus Gladiobranchus
  - Genus Uraniacanthus?
 
 
 References
   - ^ Hanke, Gavin F.; Davis, Samuel P.; Wilson, Mark V.H. (2001). "New species of the acanthodian genus Tetanopsyrus from northern Canada, and comments on related taxa". Journal of Vertebrate Paleontology. 21 (4): 740–753. doi:10.1671/0272-4634(2001)021[0740:NSOTAG]2.0.CO;2. 
  
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 | †Sinacanthidae |  - Hunanacanthus
  - Neosinacanthus
  - Sinacanthus
  - Tarimacanthus
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 | †"Ischnacanthiformes" |  - Acanthospina
  - Campylodus
  - Granulacanthus
  - Machaeracanthus?
  - Onchus
  - Serradentus
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 | Ischnacanthidae |  - Arcticacanthus
  - Arenaceacanthus
  - Atopacanthus
  - Bracteatacanthus
  - Cacheacanthus
  - Erymnacanthus
  - Euryacanthus
  - Gomphonchus
  - Grenfellacanthus
  - Ischnacanthus
  - Marsdenius?
  - Persacanthus
  - Plectrodus
  - Rockycampacanthus
  - Rohonilepis
  - Taemasacanthus
  - Tricuspicanthus
  - Xylacanthus
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 | Podoliacanthidae |  | 
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 | Poracanthodidae |  - Gomphonchoporus
  - Machaeraporus
  - Obruchevacanthus?
  - Poracanthodes
  - Radioporacanthodes
  - Taimyrolepis
  - Trundlelepis
  - Zemlyacanthus
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 | † |  | 
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 | †Acanthodiformes |  | 
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 †"Climatiiformes" and related taxa |  | 
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 | †Incertae sedis |  | 
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 "Conventionally defined chondrichthyans" |  | 
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"Conventionally defined chondrichthyans"  | 
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 | †Altholepidiformes? |  | 
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 | †Elegestolepidida? |  | 
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 | †Listracanthidae |  | 
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 | †Mongolepidida |  |  | Mongolepididae |  - Mongolepis
  - Rongolepis
  - Sodolepis
  - Taklamakanolepis
  - Teslepis
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 | Shiqianolepidae |  - Chenolepis
  - Shiqianolepis
  - Tielikewatielepis
  - Xiaohaizilepis
  - Xinjiangichthys
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 | †Tchunacanthidae |  - Fecundosquama
  - Lenacanthus
  - Tchunacanthus
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 | †Vesperaliidae |  - Acanthacanthus
  - Vesperalia
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 | †Others |  - Altacollum
  - Canyonlepis?
  - Frigorilepis?
  - Funicristata
  - Gualepis
  - Ivanelepis
  - Jolepis
  - Karksilepis
  - Lunalepis
  - Modicucollum
  - Nobilesquama
  - Nostolepis
  - Nostovicina
  - Ohiolepis
  - Seretolepis
  - Serpensiugum
  - Tuvalepis
  - Verrucasquama
  - Wellingtonella?
  - Yuanolepis
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   Taxon identifiers  | 
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| Diplacanthiformes |  | 
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