Theria, hija sottoklassi ta' mammiferi, (il-plaċentati u l-marsupjali), fil-klassi Mammalia,b' 2 infraklassi (Metatheria u Eutheria), b' 6 superordnijiet (Ameridelphia, Australidelphia, Xenarthra, Afrotheria, Euarchontoglires, u Laurasiatheria), u b' 28 ordni (Didelphimorphia, Paucituberculata, Microbiotheria, Dasyuromorphia, Peramelemorphia, Notoryctemorphia, Diprotodontia, Pilosa, Cingulata, Afrosorcida, Macroscelidea, Tubulidentata, Hyracoidea, Proboscidea, Sirenia, Rodentia, Lagomorpha, Primates, Scandentia, Dermoptera, Soricomorpha, Erinaceomorpha, Chiroptera, Perissodactyla, Cetacea, Artiodactyla, Carnivora, Pholidotaa).