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

Abstract

Around 88 large vertebrate taxa disappeared from Sahul sometime during the Pleistocene, with the majority of losses (54 taxa) clearly taking place within the last 400,000 years. The largest was the 2.8-ton browsing Diprotodon optatum, whereas the ∼100-to 130-kg marsupial lion, Thylacoleo carnifex, the world's most specialized mammalian carnivore, and Varanus priscus, the largest lizard known, were formidable predators. Explanations for these extinctions have centered on climatic change or human activities. Here, we review the evidence and arguments for both. Human involvement in the disappearance of some species remains possible but unproven. Mounting evidence points to the loss of most species before the peopling of Sahul (circa 50-45 ka) and a significant role for climate change in the disappearance of the continent's megafauna. megafauna extinction | Pleistocene extinctions | archaeology | human colonization | faunal turnover

From ratites to rats: the size of fleshy fruits shapes species' distributions and continental rainforest assembly

“…The fossil record suggests that in the Eocene to early Miocene, many species with large fleshy fruits had continent-wide distributions [32], as did the larger vertebrates capable of dispersing them [8]. During the glacial rspb.royalsocietypublishing.org Proc.…”

“…Continental distributions and ecological interactions within and between the Australian rainforest flora and fauna have been unevenly affected by shifting environmental and climatic conditions [7,8]. Extensive contractions of rainforest vegetation during the Oligo-Miocene and on into the Pleistocene resulted in a considerable loss of vertebrate diversity.…”

What caused extinction of the Pleistocene megafauna of Sahul?

“…Several authors argue that over the last 450 ka (thousands of years) the climate of Sahul became more variable and arid. This is thought to have placed increasing environmental stress on large vertebrates, reducing their distribution and abundance and causing a staggered series of extinctions over several glacial cycles [6,21,22]. A third hypothesis envisages anthropogenic fire as a cause of extinction of at least some megafauna.…”

“…Today, Sahul has no native terrestrial animal larger than about 40 kg, but for much of the Pleistocene it supported diverse large vertebrates up to almost three tonnes [6,15,16]. The overkill hypothesis proposes that human hunting drove these animals extinct.…”

“…The 'marvellous fact' of megafaunal extinction is now far better described than it was in Wallace's lifetime, but its cause is controversial. The two most widely accepted agents of extinction are human impact and climate change, but whether one or the other was dominant and how their importance varied globally is unclear [2][3][4][5][6].…”