[Phylum] Chordata Bateson, 1885 - chordates
   Subphylum Craniata auct.
     Infraphylum Vertebrata Lamarck, 1801 - vertebrates
       Class Petromyzontida [monotypic] - lampreys see Class Petromyzonti
         [†Pipisciidae Halstead, 1993, nom. nud.]
           1 Genus †Pipiscius Bardack & Richardson, 1977