Aridity, faunal adaptations and Australian Late Pleistocene extinctions

The faunal extinctions of the Late Pleistocene saw the disappearance of a suite of giant marsupials, birds and reptiles from the Australian landscape. Attempts to explain these extinctions have invoked human activities and climate change as one or other of the primary drivers. Recently, the identification of some faunal species having adaptations to aridity has been forwarded as evidence that climate change could not have had a major role in the process. By default, humans must have been responsible. The notion of aridity and adaptations to aridity is examined in this paper with respect to the extant Red Kangaroo ('Macropus rufus') and the extinct giant kangaroo 'Procoptodon goliah' in particular. The few sites known that document intact Late Pleistocene faunal sequences are also considered in an attempt to unravel climatic versus human influences. A mounting body of evidence points to considerable climate change in the lead up to, during and after the period sometimes referred to as the 'extinction window' (between ~50 and 40 ka). How many species were present at the time of human arrival remains unclear and there remains little evidence of a human-megafauna coexistence. The case for a primary human role in the extinction process is inferred rather than proven and further palaeoenvironmental studies are needed to clarify the role of climate change in this process.