I have a mammalogy lab exam on coming up on Monday. One third of the test is on marsupial phylogenetic orders and families. Marsupials are mammals without real placenta. Non placental mammals are in a subclass of Mammalia called called Theria and whithin that an infraclass called Metatheria. Within the infraclass of Metatheria there are seven orders. The common synapomorphies of the metatherians include the presence of palatal vacuities (holes in the palate, a hooked angular process in the dentary bone (except the koalas), a deciduous premolar, twinned entoconid and hypoconulid, and stlyar shelf with cusps on the upper molars
In Order Diprotodontia there are eight families. Potoroidae, Acrobatidae, Petauridae, Pseudocheiridae, Macropodidiae, Vombatidae, Phascolarctidae, and Phalangeridae.
In Order Peramelemorphia there is on family which is Peramelidae.
In Order Dasyuridae has one family - Dasyuromorphia.
In Order Didelphimorphia it is also monotypic with familiy Didelphidae and same with Order Microbiotheria with family Microbiotheriidae.