Phylum Chordata Bateson, 1885 - chordates
Class Aves Linnaeus, 1758 - birds
see Subclass Aves Linnaeus, 1758
Subclass Neornithes Gadow, 1893
see Clade Neornithes Gadow, 1893
Superorder Neognathae Pycraft, 1900
see Cohort Neognathae Pycraft, 1900
Order Charadriiformes Huxley, 1867 - shorebirds, gulls, auks
Family Alcidae Vigors, 1825 - auks
Genus Ptychoramphus Brandt, 1837
Ptychoramphus aleuticus (Pallas, 1811) - Cassin's auklet