Vertebrata Cuvier, 1812 - vertebrates see Infraphylum Vertebrata Lamarck, 1801
   Class Agnatha Cope, 1889 [paraphyletic]
     Subclass Cephalaspidomorpha see Class Agnatha Cope, 1889
       1 Order †Osteostraci Lankester, 1868 - osteostracans see Order Cephalaspidiformes Halstead Tarlo, 1967
       2 Order †Galeaspida Liu, 1965 see Order Galeaspidiformes
       3 Order †Anaspida Traquair - anaspids see Class Anaspida Traquair
       4 Order Petromyzontiformes Berg, 1940 - lampreys