Timing and dynamics of Late Pleistocene mammal extinctions in southwestern Australia

Abstract

Explaining the Late Pleistocene demise of many of the world's larger terrestrial vertebrates is arguably the most enduring and debated topic in Quaternary science. Australia lost >90% of its larger species by around 40 thousand years (ka) ago, but the relative importance of human impacts and increased aridity remains unclear. Resolving the debate has been hampered by a lack of sites spanning the last glacial cycle. Here we report on an exceptional faunal succession from Tight Entrance Cave, southwestern Australia, which shows persistence of a diverse mammal community for at least 100 ka leading up to the earliest regional evidence of humans at 49 ka. Within 10 millennia, all larger mammals except the gray kangaroo and thylacine are lost from the regional record. Stable-isotope, charcoal, and small-mammal records reveal evidence of environmental change from 70 ka, but the extinctions occurred well in advance of the most extreme climatic phase. We conclude that the arrival of humans was probably decisive in the southwestern Australian extinctions, but that changes in climate and fire activity may have played facilitating roles. One-factor explanations for the Pleistocene extinctions in Australia are likely oversimplistic.

Continuity of mammalian fauna over the last 200,000 y in the Indian subcontinent

“…Indian ecosystems are subject to the influence and strength of the Indian summer monsoon (9), and the subcontinent is likely to have been one of the first regions reached by early modern humans leaving Africa in the Late Pleistocene (10,11), with potential repercussions for mammalian communities. Human impact on mammals in regions beyond India has been much discussed (1,3), but the influence of modern human arrival on faunal populations in South Asia remains unknown, as does the possible effect of the ∼74 ka Toba volcanic supereruption (12). The Indian subcontinent therefore presents a critical, but poorly documented, region for investigating faunal responses to climatic, volcanic, and anthropogenic-driven change during the Pleistocene.…”

“…Climate change and overhunting or habitat disruption by humans are typically cited as causes for the widespread disappearance of these mammals, but research in Africa and a growing understanding of fauna-ecosystem interactions suggests that single-factor explanations for faunal extinctions are overly simplistic (2−5). Furthermore, the simultaneous disappearance of smaller mammalian taxa in some regions (6), but not in others (3), suggests that Late Pleistocene mammalian population analyses should also consider multiple causes acting on different taxa at a range of spatial and temporal scales and that wider ecological perspectives should be embraced (1). Securely dated Pleistocene fossil assemblages from less-welldocumented regions of the world therefore offer considerable potential to further our knowledge about the factors affecting past faunal distributions and diversity.…”

A new species of Miocene wombat (Marsupialia, Vombatiformes) from Riversleigh, Queensland, Australia, and implications for the evolutionary history of the Vombatidae

“…This is not sur- Results of the phylogenetic analysis with additional species added (relative branching order of these additional taxa are shown here as not resolved) against the geological time scale (Gradstein et al, 2012). Age span of deposits containing all known wombat taxa are provided, with black bars indicating certainty (such as radiometrically dated sites) and grey indicating uncertainty (ages are based on Archer and Wade, 1976;Archer et al, 1989Archer et al, , 1997Archer et al, , 2016Arena et al, 2016;Beck, 2008;Beheregaray et al, 2000;Black et al, 2012b;Cupper and Duncan, 2006;Dawson, 1985;Hope and Wilkinson, 1982;Myers et al, 2001Myers et al, , 2017Piper et al, 2006;Pledge, 1992;Price et al, 2009Price et al, , 2011Prideaux et al, 2010;Vickers-Rich et al, 1991;Roberts et al, 2001;Stirton et al, 1967;Taylor et al, 1994;Tedford et al, 2006;Travouillon et al, 2006Travouillon et al, , 2011Whitelaw 1989Whitelaw , 1991Woodhead et al, 2014). Age of split between taxa is based on oldest possible deposits containing those taxa and as such will change as more information becomes available.…”

What caused extinction of the Pleistocene megafauna of Sahul?

“…Two such cases from southern Australia, spanning periods of 500-150 ka, revealed long-term stability in the mammalian assemblage, despite climate-related variation in the relative abundance of small and large species. Large species declined relative to smaller ones during dry periods, probably owing to local range contractions, but rebounded subsequently [64,65].…”