<==o †Ischnacanthiformes Berg, 1940
   |?- †Acanthospina irregulare Valiukevičius, 2003, E.Dev. NEEu.
   |?- †Granulacanthus joenelsoni Hanke, Wilson & Lindoe, 2001
   |?- †Onchus graptolitarum Fritsch, 1907 [Leptocheles] E.Sil. EEu.
   |?-o †Acritolepidae Valiukevicius & Burrow, 2005
   |  |--o †Acritolepis Valiukevicius, 2003
   |  |  |-- †A. ushakovi Valiukevicius, 2003
   |  |  `-- †A. urvantsevi Valiukevicius, 2003
   |  |-- †Monospina erecta Valiukevicius, 2003
   |  |?- †Nerepisacanthus denisoni Burrow, 2011
   |  `--o †Pechoralepis Valiukevicius & Burrow, 2005 [Nostolepis Pander, 1856 in partim]
   |     |-- †P. adzvensis (Valiukevicius, 2003) [†Nostolepis adzvensis Valiukevicius, 2003]
   |     |-- †P. valentinae (Valiukevicius, 2003) [†Nostolepis valentinae Valiukevicius, 2003]
   |     `-- †P. zinaidae (Valiukevicius, 2003) [†Nostolepis zinaidae Valiukevicius, 2003] [type]
   |--o †Poracanthodidae Vergoossen, 1999
   |  |?- †Zemlyacanthus menneri (Valiukevicius, 1992)
   |  |--o †Poracanthodes Brotzen, 1934 [jr. synon. of Gomphonchus?? (Carroll, 1988)]
   |  |  |-- †P. punctatus Brotzen, 1934
   |  |  |-- †P. stonehousensis
   |  |  |--+-- †P. subporosus Valiukevičius, 1998
   |  |  |  `?- †P. sp. cf. P. subporosus Valiukevičius, 1998
   |  |  `-- †P. menneri Valiukevičius, 1992 [= Zemlyacanthus menneri (Valiukevicius, 1992)]
   |  |--o †Radioporacanthodes Vergoossen, 1999; L. Dev. NEu. Aust.
   |  |  |-- †R. porosus (Brotzen, 1934) [Poracanthodes porosus Brotzen, 1934]
   |  |  `?- †R. sp. cf. R. porosus (Brotzen, 1934) [†Poracanthodes sp. cf. Poracanthodes porosus Brotzen, 1934 sensu Valiukevičius, 2003]
   |  |--o †Gomphonchoporus Vergoossen, 1999; L. Sil. E. Dev. NEu. Aust.
   |  |  `-- †G. hoppei (Gross, 1947) [Gomphodus hoppei Gross, 1947]
   |  `?-o †Trundlelepis Burrow, 1997
   |     |-- †T. cervicostulata Burrow, 1997
   |     `-- †T. sp. [Burrow, 2003] E.Dev. Aust.
   `--o †Ischnacanthidae Woodward, 1891
      |--o †Acanthodopsis Penn. Eu. 
      |  `-- †A. wardi
      |-- †Acanthopora transitans Valiukevičius, 2003
      |--o †Apateacanthus U. Dev. NA. [probably a chondrichthyan fin spine (Burrow, 2004)]
      |  `-- †A. vetustus (Clarke, 1885)
      |-- †Arcticacanthus bicostatus Valiukevičius, 2003
      |-- †Arenaceacanthus arcuatacanalis Valiukevičius, 2004; L.Sil. EEu.
      |--o †Atopacanthus Hussakof & Bryant, 1918; U. Dev. NA. Eu. EEu.
      |  |-- †A. peculiaris (Hussakof, 1913) [Apateacanthus peculiaris Hussakof, 1913]
      |  |-- †A. dentatus Hussakof & Bryant, 1918
      |  |-- †A. sp. [Ørvik, 1957]
      |  |-- †A. sp. [Ørvik, 1960]
      |  |-- †A. sp. [Novitskaya & Obruchev, 1967]
      |  |-- †A. sp. [Jessen, 1973]
      |  `?- †A.? ambrockensis
      |?- †Bracteatacanthus assiduus Valiukevičius, 2004; L.Sil. EEu.
      |-- †Bryantonchus peracutus (Bryant, 1934) Burrow, 2007; L.Dev. WNAm.
      |-- †Cacheacanthus utahensis Burrow, 2007; L.Dev. WNAm.
      |?- †Doliodus ?M.Dev. NA. [is a basal elasmobranchian chondrichthyan (Miller, Cloutier & Turner, 2003)]
      |-- †Erymnacanthus clivus Blais, Hermus & Wilson, 2015 [Ischnacanthus gracilis (Egerton); Bernascek & Dineley, 1977 (in partem)] E.Dev. WNAm.
      |-- †Euryacanthus rugosus Blais, Hermus & Wilson, 2015 [Ischnacanthus gracilis (Egerton); Bernascek & Dineley, 1977 (in partem)] E.Dev. WNAm.
      |-- †Grenfellacanthus zerinae Long, Burrow & Richie, 2004
      |--o †Gomphonchus Gross, 1971 [Gomphodus; Poracanthodes] L.Sil. Eu. EEu. Aust. E.Dev. NA. Spits. Gr. ?SAs.
      |  |?- †G.? bogongensis Burrow, 1997
      |  |?- †G.? minutus
      |  |?- †G.? turnerae Burrow & Simpson, 1995
      |  |-- †G. hoppei
      |  |-- †G. mediocostatus
      |  |-- †G. sandelensis (Pander, 1856)
      |  `-- †G. nordicus Valiukevičius, 2003
      |--o †Helenacanthus E.Dev. NA.
      |  `-- †H. incurvus
      |--o †Ischnacanthus Powrie, 1864 E.Dev. Eu. NA.
      |  |-- †I. kingi 
      |  |-- †I. wickhami
      |  `-- †I. gracilis (Egerton, 1861)
      |--o †Machaeracanthus Newberry, 1857 [Dinacanthodes] E.-M.Dev. Eu. L.Dev. NAf. E.-M.Dev. NA.
      |  `-- †M. kayseri
      |--o †Marsdenius Wellburn, 1902; Miss. Eu.
      |  |-- †M. acuta Wellburn, 1902
      |  `-- †M. summiti Wellburn, 1902
      |--o †Persacanthus Janvier, 1977; E.Dev. SWAs.
      |  |-- †P. kermanensis Janvier, 1977
      |  `-- †P. simpsonensis Reed, 1986
      |?- †Plectrodus mirabilis L.Sil. Eu.
      |?-o †Podoliacanthus Voichyshyn & Szaniawski, 2012; E.Dev. EEu.
      |  |-- †P. zychi Voichyshyn & Szaniawski, 2012
      |  |?- †P. sp. 1 [Voichyshyn & Szaniawski, 2012]
      |  `?- †P. sp. 2 [Voichyshyn & Szaniawski, 2012]
      |-- †Rockycampacanthus milesi Long, 1986; E.Dev. Aust.
      |-- †Rohonilepis breviornatus Valiukevičius, 2004; L.Sil. EEu.
      |--o †Taemasacanthus Long, 1986 [incl.? Cambaracanthus Lindley, 2000; Cavanacanthus Lindley, 2000]; E.Dev. Aust.
      |  |-- †T. porca Lindley, 2000
      |  |-- †T. narrengullenensis Lindley, 2002
      |  |-- †T. cooradigbeensis Lindley, 2002
      |  |-- †T. erroli Long, 1986
      |  |?- †Cambaracanthus goodhopensis Lindley, 2000; E.Dev Aust.
      |  `?- †Cavanacanthus warrooensis Lindley, 2000; E.Dev Aust.
      |--o †Tricuspiacanthus Blais, Hermus & Wilson, 2015 [Ischnacanthus Powrie; Bernascek & Dineley, 1977 (in partem)] E.Dev. WNAm.
      |  |-- †T. gannitus Blais, Hermus & Wilson, 2015 [Ischnacanthus gracilis (Egerton); Bernascek & Dineley, 1977 (in partem)]
      |  `-- †T. pisciculus Blais, Hermus & Wilson, 2015 [Ischnacanthus gracilis (Egerton); Bernascek & Dineley, 1977 (in partem)]
      |--o †Uraniacanthus Miles, 1973; E.Dev. Eu.
      |  `-- †U. spinosus
      `--o †Xylacanthus Ørvig, 1967; L.Sil. NWNA. E.Dev. Spits.
         |-- †X. kenstewarti Hanke, Wilson & Lindoe, 2001
         |-- †X. minutus Gagnier & Goujet, 1997
         `-- †X. grandis Ørvig, 1967

Reference(s):