Mammalia (from Wikipedia)

A somewhat standardized classification system has been adopted by most current mammalogy classroom textbooks. The following taxonomy of extant and recently extinct mammals is from Vaughan et al. (2000).

Class Mammalia
Subclass Prototheria: monotremes: platypuses and echidnas
Subclass Theria: live-bearing mammals
Infraclass Metatheria: marsupials
Infraclass Eutheria: placentals


1 Subclass Theria
1.1 Infraclass Eutheria (Placental Mammals)
1.1.1 Order Afrosoricida (tenrecs and golden moles)
1.1.2 Order Macroscelidea
1.1.3 Order Tubulidentata
1.1.4 Order Hyracoidea
1.1.5 Order Proboscidea
1.1.6 Order Sirenia
1.1.7 Order Cingulata (Armadillos)
1.1.8 Order Pilosa (Anteaters, and Sloths)
1.1.9 Order Scandentia (Treeshrews)
1.1.10 Order Dermoptera (Colugos)
1.1.11 Order Primates
1.1.12 Order Rodentia
1.1.13 Order Lagomorpha
1.1.14 Order Erinaceomorpha
1.1.15 Order Soricomorpha
1.1.16 Order Chiroptera (Bats)
1.1.17 Order Pholidota
1.1.18 Order Cetacea
1.1.19 Order Carnivora
1.1.20 Order Perissodactyla
1.1.21 Order Artiodactyla

1 Subclass Prototheria (the monotremes)
1.1 Order Monotremata (monotremes, egg-laying mammals)

2 Subclass Theria
2.1 Infraclass Metatheria (marsupials)
2.1.1 Order Didelphimorphia (American opossums)
2.1.2 Order Paucituberculata (shrew opossums)
2.1.3 Order Microbiotheria (Monito del Monte)
2.1.4 Order Notoryctemorphia (marsupial moles)
2.1.5 Order Dasyuromorphia (marsupial carnivores)
2.1.6 Order Peramelemorphia (bandicoots and bilbies)
2.1.7 Order Diprotodontia (diprotodont marsupials)
2.1.7.1 Suborder Vombatiformes (wombats and koalas)
2.1.7.2 Suborder Phalangeriformes (possums and gliders)
2.1.7.3 Suborder Macropodiformes (kangaroos, wallaroos, wallabies