Australian Mammals: Zoogeography and Evolution

Abstract

A review of the Australo-Papuan mammal fauna shows it to be composed of four monotreme, about 145 marsupial, and about 214 placental species. Endemism is high in every group except bats. Virtually all major ways of life (except those of rodents and bats) have been filled by marsupials, and their great diversity of body forms reflects this. Convergence with placental couterparts on other continents may involve the whole body (in the superficial sense) but is usually restricted to parts of the body or sets of structures. Australia provides the best example of evolution and radiation in an isolated fauna to be found among mammals. The placental rodents and bats occupy essentially the same kinds of niches as on other continents, and they show virtually no striking structural novelties. This confirms that the rodents, at least, are late colonizers, despite the degree of ecological radiation achieved. The pre-Tertiary Australian fauna was presumably made up of monotremes and ancestral marsupials. No fossils are known, however, before the end of the Oligocene or early Miocene, by which time the contemporary families had differentiated (Notoryctes, the marsupial mole, however, is unknown as a fossil). Only one form known from the early Miocene (Wynyardia, Wynyardidae) is presumed to be extinct before the Pleistocene. One family (Diprotodontidae) and two sub-families (Sthenurinae, Thylacoleoninae) became extinct in early Recent, or mid-Recent times. The contemporary mammal fauna of Australia is reviewed with respect to the biology and ecology of the major types, fossil history, radiation, and speciation.