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

Sites mentioned in the main text. The continental limits of Sahul are defined by the −130-m bathymetry line, and Sahul incorporates Australia, New Guinea, and Tasmania. The Nullarbor Plain caves contain middle Pleistocene fossil deposits. Kings Creek is located in the eastern Darling Downs region.

Extinction chronology of Pleistocene megafaunal taxa in Sahul (88 species). For many species, terminal dates are debated, as is the definition of a “secure” date. If the selection criteria of Roberts et al. (9) are applied, as few as 8 species clearly survived to the time of human colonization of Sahul. Species reported to overlap with humans but lacking contextual information linking the dates to the taxa in question are illustrated in gray. The majority of taxa cannot be placed within the time frame of human arrival, and many lack reliable radiometric dates altogether, with some of the taxa claimed to have been the victims of human-mediated extinction known only from the Pliocene (e.g., Euryzygoma dunense). Of those taxa known to overlap with people, some persist well beyond a previously proposed 51- to 39-ka “extinction window” (9), whereas most of those falling within this window are not securely linked to the dates (six of nine taxa). Of those taxa potentially surviving until more recently than ∼50 ka, almost half are from New Guinea.

Late Pleistocene temporal occurrences of megafauna from the intensively sampled Kings Creek Catchment, Darling Downs, southeastern Queensland (13), in relation to the hypothesized continental megafaunal extinction window and earliest evidence of human colonization. Rarefaction, bootstrapping, and associated statistical analyses demonstrate that the apparent temporally progressive loss of megafauna was a real phenomenon and cannot simply be explained as a result of taphonomic or sampling biases (14). Importantly, the data clearly point to prehuman climate changes as a driver of the losses and do not support the hypothesis that there was a local mass extinction of all megafauna at or around the hypothesized extinction window.