vertebrates Lamarck, 1801 - vertebrates see Infraphylum Vertebrata Lamarck, 1801
   †Pteraspidimorphi [paraphyletic]
     †Heterostraci Lankester, 1868, sedis mutabilis - heterostracans
       Family †Cyathaspididae Kiaer, 1932, nom. praeval. [paraphyletic]
         Order †Pteraspidiformes Berg, 1940
           [Suborder] †Psammosteida Kiaer, 1932 see Suborder Psammosteoidei Kiaer, 1932
             Genus †Drepanaspis Schlüter, 1887