ABSTRACT
North America does not have a monopoly in disharmonious communities. In Australia, an Early Pliocene fauna from Victoria-the Hamilton local fauna-contains several extant genera whose living species live almost exclusively in rain forest or rainforest fringes (Flannery et al. 1992). The indication is, therefore, that the Pliocene fauna lived in rainforest environment, but a more complex rain forest than exists today. Modern representatives of four genera (Hypsiprymnodon, Dorcopsis, Dendrolagus, and Strigocuscus) are almost entirely rain-forest dwellers, but they live in different kinds of rain forest. Living species of Dorcopsis (kinds of kangaroo) live in high mountain forests, lowland rain forests, mossy montane forests, and mid-montane forests. Living species of Dendrolagus (tree kangaroos) live mainly in montane rain forests. Hypsiprymnodon moschatus (the musky rat-kangaroo) is restricted to rain forest where it prefers wetter areas. The modern New Guinea species Strigocuscus gymnotus is chiefly a rain-forest dweller, though it also lives in areas of regrowth, mangrove swamps, and woodland savannah. Living species of Thylogale (pademelons) live in an array of environments, including rain forests, wet sclerophyll forests, and high montane forests. Other modern relatives of the fossils in the Hamilton fauna, which includes pseudocheirids, petaurids, and kangaroos and wallabies, live in a wide range of habitats. It contains two species, Trichosurus (brushtail possums) and Strigocuscus (cuscuses), whose ranges do not overlap at present. It is thus a disharmonious assemblage. Taken as a whole, the Hamilton mammalian assemblage suggests a diversity of habitats in the Early Pliocene. The environmental mosaic consisted of patches of rain forest, patches of other wet forests, and open area patches. Nothing like this environment is known today.
