Even Wallace was puzzled by the fauna of Celebes, as Sulawesi was known: he pointed out the high proportion of endemic species in several groups and the unusual combination of species with links to Asia and the more western islands and species with links to the south and east. He eventually drew his line to the west of the island, but was well aware of its porosity. Of course the idea of a transition zone is sensible, but although cassowaries may have a claw stretched into this zone, it's hardly a justification for labelling them as Asian.
Very true. My point was only that their distribution relative to Wallace's Line is hardly a justification for labelling them Australasian. And that biogeography is fun
On balance Sulawesi has a Sunda-type tetrapod fauna according to Holt et al. So there are Asian marsupials: the question is why they did not penetrate further when they can compete against placental mammals.
