The remains of two species (a macropodid and a diprotodontid) of large, extinct marsupials have been recovered from cave and fluvial deposits in Irian Jaya. The sites are located at 2,800–2,950 m elevation in what is today upper montane forests, although at the time of deposition (41,500 ± 1,500 ybp for the fluvial sediments) the area was covered with subalpine herbfield. The diprotodontid is described here asMaokopia ronaldigen. et sp. nov., while the macropodid is described asProtemnodon hopeisp. nov. It is likely that these were the only really large marsupial species that inhabited the region.