Pliocene and earlier Pleistocene marsupial evolution in southeastern Australia
RICHARD H. TEDFORD1, ROD T. WELLS2 and GAVIN J. PRIDEAUX3
1Department of Vertebrate Paleontology, American Museum of Natural History, New York, NY 10024, USA
2School of Biological Sciences, Flinders University, Bedford Park, SA
3Dept of Earth and Planetary Sciences, Western Australian Museum, Perth, WA
In recent years investigation of Australian Pliocene and earlier Pleistocene fossil occurrences and new methods for their dating has made it evident that there have been important changes in the mammal fauna during the past 5 million years. We review these data and believe they support the following general conclusions. By early Pliocene time (4–5 Ma) many marsupial genera characteristic of the late Cainozoic had appeared. Some species of extinct genera characteristic of the Pleistocene were also present in the late Pliocene (2 Ma). Megafaunal marsupials, notably Diprotodon, and the beginning of the spectacular radiation of a large sthenurine kangaroos, accompanied remnants of Miocene taxa (e.g. Ektopodontidae, and early macropodines like Prionotemnus and Kurrabi), into the early Pleistocene. This turnover, extending across the Pliocene Pleistocene boundary, roughly corresponds with the time of northward withdrawal of rainforest from southeastern Australia and its replacement there by open Eucalyptus forest. Dust flux from the continent into the Tasman Sea and Indian Ocean increased in volume and frequency over the last four glacial cycles (400 ka) reflecting the progressive denudation of the Australian inland. Procoptodon sthenurines, the last megafaunal genus to appear, arose early in the Pleistocene near the initiation of 100 ka glacial cycling. During the last glacial cycle (120–20 ka) most of the megafauna including all sthenurine species became extinct.
Key words: Australia, Pliocene, Pleistocene, monotremes, marsupials, placentals, megafauna, evolution.