ORIGINS OF THE AUSTRALO-PACIFIC LAND MAMMAL FAUNA

After evaluation of relevant recent geological and systematic literature, a scenario of the history of land mammals in the Australo-Pacific region is developed, as follows. Monotremes probably originated in the Australian section of Gondwana during the Cretaceous. Australidelphians reached Australasia at some time between the mid-Cretaceous and Eocene by waif dispersal from South America. The ancestors of the New Zealand chiropteran genus Mystacina arrived from South America by waif dispersal, probably about 35 million years ago. The remaining Chiroptera of the region are Asiatic in origin, and have been arriving throughout the Neogene, and probably later Paleogene. The Australasian murids are polyphyletic and compromise; New Guinean Old Endemics, New Guinean Rattus, Australian Old Endemics, and Australian Rattus. Murids had begun to arrive by the early Pliocene, and have continued to invade from Asia up to the present.

Current estimates of the ages of some Australian Tertiary mammal faunas are in conflict with other data examined here. It is suggested that the Pinpa and Etadunna faunas may date to the Oligocene, and the “upper” Riversleigh fauna, and possibly the Bullock Creek fauna, to the early Miocene.