Vertebrata Cuvier, 1812 - vertebrates
Gnathostomata
Teleostomi
Tetrapoda Goodrich, 1930
Amniota Haeckel, 1866 - amniotes
Class Mammalia Linnaeus, 1758 - mammals
Subclass Theria Parker & Haswell, 1897
Theria of Metatherian-Eutherian grade
Infraclass Eutheria Gill, 1872
Order Sirenia Gill, 1872 - sea cows
1 Family †Prorastomidae Cope, 1889
2 Family Dugongidae Gray, 1821 - dugong and sea cow
3 Family Manatidae Gray, 1821, nom. illeg.
see Family Trichechidae Gill, 1872
4 Family †Protosirenidae Sickenberg, 1934
see Subfamily Protosireninae Sickenberg, 1934