Chordata Bateson, 1885 - chordates
   Class †Ostracophori
     1 Order †Heterostraci Lankester, 1868 - heterostracans see Subclass Heterostraci Lankester, 1868
     2 Order †Osteostraci Lankester, 1868 - osteostracans see Order Cephalaspidiformes Halstead Tarlo, 1967
     3 ?Order †Antiarcha (Cope, 1885) [monotypic] see [unranked] Antiarchi Cope, 1885
     4 Order †Anaspida Traquair - anaspids see Class Anaspida Traquair
     5 Order †Cycliae [monotypic]