[mainly] After Parker, 1982

<==o Aplacophora von Ihering, 1876 (piilojalkaiset) [c. 150 species]
   |?-o †Heloplacidae Cherns, 2004
   |  |-- †Aceanoplax Sutton, Briggs, Siveter & Siveter, 2001; Sil. WEu.
   |  `--+--+-- †Heloplax Cherns, 1998b; Sil.
   |     |  `-- †Enetoplax Cherns, 1998b; Sil.
   |     `--+?- †Preacanthochiton
   |        `-- †Arctoplax Cherns, 1998b; Sil.
   |?- Solenogastres Gegenbaur, 1878 [Neomeniomorpha; Adenopoda (cf. Salvini-Plawen, 1978)] (matonilviäiset)
   `?- Caudofoveata [Crystallophrissonidea; Chaetodermatidea]

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