[Phylum] Chordata Bateson, 1885 - chordates Subphylum Craniata auct. Infraphylum Vertebrata Lamarck, 1801 - vertebrates Class Petromyzontida [monotypic] - lampreys see Class Petromyzonti Order Petromyzontiformes Berg, 1940 - lampreys Family †Mayomyzontidae Bardack & Zangerl, 1971 1 Genus †Mayomyzon Bardack & Zangerl, 1968