Late-surviving megafauna in Tasmania, Australia, implicate human involvement in their extinction

Abstract

Establishing the cause of past extinctions is critical if we are to understand better what might trigger future occurrences and how to prevent them. The mechanisms of continental late Pleistocene megafaunal extinction, however, are still fiercely contested. Potential factors contributing to their demise include climatic change, human impact, or some combination. On the Australian mainland, 90% of the megafauna became extinct by Ϸ46 thousand years (ka) ago, soon after the first archaeological evidence for human colonization of the continent. Yet, on the neighboring island of Tasmania (which was connected to the mainland when sea levels were lower), megafaunal extinction appears to have taken place before the initial human arrival between 43 and 40 ka, which would seem to exonerate people as a contributing factor in the extirpation of the island megafauna. Age estimates for the last megafauna, however, are poorly constrained. Here, we show, by direct dating of fossil remains and their associated sediments, that some Tasmanian megafauna survived until at least 41 ka (i.e., after their extinction on the Australian mainland) and thus overlapped with humans. Furthermore, a vegetation record for Tasmania spanning the last 130 ka shows that no significant regional climatic or environmental change occurred between 43 and 37 ka, when a land bridge existed between Tasmania and the mainland. Our results are consistent with a model of human-induced extinction for the Tasmanian megafauna, most probably driven by hunting, and they reaffirm the value of islands adjacent to continental landmasses as tests of competing hypotheses for late Quaternary megafaunal extinctions. Paleoclimate ͉ Pleistocene ͉ sea level change ͉ island colonization ͉ human hunting

Climate change frames debate over the extinction of megafauna in Sahul (Pleistocene Australia-New Guinea)

“…The case for a human role was buttressed by claims that MIS3 (60-28 ka) was a time of relatively stable climatic conditions (13). As such, human activities were therefore the only credible explanation for the extinctions (2,11,38).…”

Dietary responses of Sahul (Pleistocene Australia–New Guinea) megafauna to climate and environmental change

“…Similar conclusions were drawn from an OSL study undertaken by Roberts and colleagues (2001) at Cuddie Springs, in which multiple age populations were identified in the single-grain OSL data, and the authors subsequently concluded the site to have significant sediment disturbance. A similar pattern of multiple age populations was determined for a Tasmanian study of megafauna (Turney et al [2008] and discussion in Cosgrove et al [2010Cosgrove et al [ : p. 2497); however, some of these age populations were "omitted for clarity," and an age of~45 Ka was used instead. While further work is needed to better standardize the treatment of OSL data, there is still much that can be learned from the sites mentioned earlier.…”

What caused extinction of the Pleistocene megafauna of Sahul?

“…A series of recent studies restricted to specimens and sites dated with high confidence suggest that the extinctions were concentrated between 50 and 40 ka on mainland Australia [24,26,[33][34][35][36], and slightly later in Tasmania [37]. On the other hand, more extensive compilations of occurrences in the fossil record, lacking controls on date quality, suggest staggered extinction through the period from 400 to about 20 ka [6].…”