Extinction of eastern Sahul megafauna coincides with sustained environmental deterioration

Abstract

Explanations for the Upper Pleistocene extinction of megafauna from Sahul (Australia and New Guinea) remain unresolved. Extinction hypotheses have advanced climate or humandriven scenarios, in spite of over three quarters of Sahul lacking reliable biogeographic or chronologic data. Here we present new megafauna from northeastern Australia that suffered extinction sometime after 40,100 (±1700) years ago. Megafauna fossils preserved alongside leaves, seeds, pollen and insects, indicate a sclerophyllous forest with heathy understorey that was home to aquatic and terrestrial carnivorous reptiles and megaherbivores, including the world's largest kangaroo. Megafauna species diversity is greater compared to southern sites of similar age, which is contrary to expectations if extinctions followed proposed migration routes for people across Sahul. Our results do not support rapid or synchronous human-mediated continental-wide extinction, or the proposed timing of peak extinction events. Instead, megafauna extinctions coincide with regionally staggered spatio-temporal deterioration in hydroclimate coupled with sustained environmental change.

Australia’s prehistoric ‘swamp king’: revision of the Plio-Pleistocene crocodylian genusPallimnarchusde Vis, 1886

“…Jack Williams Jr., who lived in the township of Eungella, approximately 70 km west of Mackay, collected rocks and fossils throughout the Pioneer Valley and surrounding region (Steven W. Salisbury and D. Ruthenberg, 2020, personal communication). It is likely the skull came from one of the Pleistocene fluvial deposits that occur in this area, similar to those a little farther to the south at South Walker Creek, near Nebo, which were recently described by Hocknull et al (2020) .…”

“…Pallimnarchus gracilis Willis & Molnar, 1997a ; Hocknull et al, 2020 , pp. 9–11 in Supplementary Information…”

Figure 11: Paludirex gen. nov., rostra in anterior view.

“…Full-size  DOI: 10.7717/peerj.10466/ fig-7 who lived in the township of Eungella, approximately 70 km west of Mackay, collected rocks and fossils throughout the Pioneer Valley and surrounding region (Steven W. Salisbury and D. Ruthenberg, 2020, personal communication). It is likely the skull came from one of the Pleistocene fluvial deposits that occur in this area, similar to those a little farther to the south at South Walker Creek, near Nebo, which were recently described by Hocknull et al (2020).…”

Disrupting paradise: Has Australian archaeology lost its way?

“…A case in point has been the quagmire surrounding the purported causes of megafaunal extinction for Australian palaeontology which desperately required new data from new sites in order to move the debate forwards. In this regard the recent paper by Hocknull et al (2020) has been a breath of fresh air and is to be applauded. The key thing to point out here, however, and that has relevance for the topic under consideration, is that the South Walker Creek site was not found by researchers, but rather by consultant archaeologists working in partnership with Aboriginal community members, doing baseline, greenfield surveys.…”