The class Mammalia is divided into two subclasses based on reproductive techniques: egg-laying mammals (monotreme

Monotreme

Monotremes are mammals that lay eggs instead of giving birth to live young like marsupials and placental mammals...

s) and mammals which give live birth (theria

Theria

Theria is a subclass of mammals that give birth to live young without using a shelled egg, including both eutherians and metatherians . The only omitted extant mammal group is the egg-laying monotremes....

ns). The latter subclass is divided into two infraclasses: pouched mammals (marsupial

Marsupial

Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central...

s) and placental mammals (eutheria

Eutheria

Eutheria is a group of mammals consisting of placental mammals plus all extinct mammals that are more closely related to living placentals than to living marsupials . They are distinguished from noneutherians by various features of the feet, ankles, jaws and teeth...

ns).

This list is, as yet, incomplete. However for reasons of space, it has been broken into two sections:

• List of placental mammals
• List of monotremes and marsupials (non-placental mammals)

See also

• List of mammal genera
• Lists of animals
• List of mammalogists
• List of regional mammals lists