Opisthokonta Cavalier-Smith 1987, nom. cl. inval. see Clade Opisthokonta Cavalier-Smith 1987 [Simpson & Medina 2020]
   Metazoa Haeckel 1874 - multicellular animals see Kingdom Animalia Linnaeus, 1758
     Epitheliozoa Ax, 1996
       Eumetazoa Bütschli, 1910 - eumetazoans
         Acrosomata Ax, 1996 see [unranked] Eumetazoa Bütschli, 1910
           Bilateria Hatschek, 1888 - bilaterians see Subkingdom Bilateria Hatschek, 1888
             Deuterostomia Grobben, 1908 - deuterostomes see Infrakingdom Deuterostomia Grobben, 1908
               Ambulacraria Metschnikoff 1881 [Halanych 1995]
                 Hemichordata Bateson, 1885 - hemichordates
                   1.1 Ptychoderidae Spengel, 1893
                   1.2 Spengelidae Willey, 1899
                   2.1 Harrimaniidae Spengel, 1901
                   2.2 Pterobranchia Lankester, 1877 see Class Pterobranchia Lankester, 1877