Vertebrata Cuvier, 1812 - vertebrates
   Class Agnatha Cope, 1889 [paraphyletic]
     Subclass Cephalaspidomorpha see Class Agnatha Cope, 1889
       Order †Osteostraci - osteostracans see Order Cephalaspidiformes
         1 Family †Tremataspidae
         2 Family †Dartmuthiidae
         3 Family †Ateleaspidae Traquair, 1899
         4 Family †Sclerodontidae
         5 Family †Cephalaspidae
         6 Family †Kiaeraspididae see Family Kiaeraspidae