Australidelphia is the superorder that contains roughly three-quarters of all marsupials, including all those native to Australasia and a single species – the monito del monte – from South America.

Analysis of retrotransposon insertion sites in the nuclear DNA of a variety of marsupials has shown that the South American monito del monte's lineage is the most basal of the superorder.

[3][4] The Australian australidelphians form a clade, for which the name Euaustralidelphia ("true Australidelphia") has been proposed (the branching order within this group is yet to be determined).

This indicates that Australidelphia arose in South America along with the other major divisions of extant marsupials, and likely reached Australia via Antarctica in a single dispersal event after Microbiotheria split off.

[3][4] Phylogeny of living Australidelphia based on the work of May-Collado, Kilpatrick & Agnarsson 2015[5] with extinct clades from Black et al. 2012[6] †Woodburnodontidae Microbiotheriidae Notoryctidae †Yaralidae Thylacomyidae Peramelidae †Chaeropodidae Peroryctidae †Thylacinidae Myrmecobiidae Dasyuridae Phascolarctidae †Thylacoleonidae ?†Wynyardiidae †Ilariidae †Maradidae Vombatidae †Palorchestidae †Diprotodontidae Burramyidae Phalangeridae ?†Pilkipildridae †Ektopodontidae †Miralinidae Acrobatidae Tarsipedidae Petauridae Pseudocheiridae ?†Balbaridae Hypsiprymnodontidae Potoroidae Macropodidae (*)This clade has been called Agreodontia by other authors since 2014.