[Phylum] Chordata Bateson, 1885 - chordates Subphylum Craniata auct. Infraphylum Vertebrata Lamarck, 1801 - vertebrates Superclass Gnathostomata Gegenbaur, 1874 - jawed vertebrates Class †Placodermi McCoy, 1848 Order †Stensioelliformes [monotypic] 1 Family †Stensioellidae Berg, 1940