Marsupialia

**Definition:** An infraclass of MAMMALS, also called Metatheria, where the young are born at an early stage of development and continue to develop in a pouch (marsupium). In contrast to Eutheria (placentals), marsupials have an incomplete PLACENTA.

**Tree numbers:** - B01.050.150.900.649.573

**Synonyms:** - Marsupials - Metatheria