[Phylum] Chordata Bateson, 1885 - chordates
   Subphylum Craniata auct.
     Infraphylum Vertebrata Lamarck, 1801 - vertebrates
       Superclass †Osteostracomorphi
         Class †Osteostraci Lankester, 1868
           Order †Thyestiformes
             Family †Procephalaspididae Stensiö, 1958
               1 Genus †Procephalaspis Denison, 1951