Search

The mechanisms leading to megafauna (>44 kg) extinctions in Late Pleistocene (126,000-12,000 years ago) Australia are highly contested because standard chronological analyses rely on scarce data of varying quality and ignore spatial complexity. Relevant archaeological and palaeontological records are most often also biased by differential preservation resulting in under-representated older events. Chronological analyses have attributed megafaunal extinctions to climate change, humans, or a combination of the two, but rarely consider spatial variation in extinction patterns, initial human appearance trajectories, and palaeoclimate change together. Here we develop a statistical approach to infer spatio-temporal trajectories of megafauna extirpations (local extinctions) and initial human appearance in south-eastern Australia. We identify a combined climate-human effect on regional extirpation patterns suggesting that small, mobile Aboriginal populations potentially needed access to drinkable water to survive arid ecosystems, but were simultaneously constrained by climate-dependent net landscape primary productivity. Thus, the co-drivers of megafauna extirpations were themselves constrained by the spatial distribution of climate-dependent water sources.

Palaeontological animal bone deposits are rarely investigated through research partnerships where the local First Nations communities have a defining hand in both the research questions asked and the research processes. Here we report research undertaken through such a partnership approach at the iconic archaeological site of Cloggs Cave (GunaiKurnai Country, East Gippsland), in the southern foothills of SE Australia's Great Dividing Range.A new excavation was combined with detailed chronometric dating, high‐resolution 3D mapping and geomorphological studies. This allowed interpretation of a sequence of stratigraphic layers spanning from a lowermost excavated mixed layer dated to between 25,640 and 48,470 cal BP, to a dense set of uppermost, ash layers dated to between 1460 and 3360 cal BP. This long and well‐dated chronostratigraphic sequence enabled temporal trends in the abundant small mammal remains to be examined.The fossil assemblage consists of at least 31 taxa of mammals which change in proportions through time. Despite clear evidence that the Old Ancestors repeatedly carried vegetation into the cave to fuel cool fires (no visible vegetation grows in Cloggs Cave), we observed little to no evidence of cooking fires or calcined bone, suggesting that people had little involvement with the accumulation of the faunal remains. Small mammal bones were most likely deposited in the cave by large disc‐faced owls, Tyto novaehollandae (Masked Owl) or Tyto tenebricosa (Sooty Owl).Despite being well dated and largely undisturbed, the Cloggs Cave assemblage does not appear to track known Late Quaternary environmental change. Instead, the complex geomorphology of the area fostered a vegetation mosaic that supported mammals with divergent habitat preferences. The faunal deposit suggests a local ancestral landscape characterised by a resilient mosaic of habitats that persisted over thousands of years, signalling that the Old Ancestors burned landscape fires to encourage and manage patches of different vegetation types and ages within and through periods of climate change. Read the free Plain Language Summary for this article on the Journal blog. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Global ecosystems underwent major changes through the Quaternary, as climates cycled from cool and dry glacial conditions to relatively warm and humid interglacial conditions. How these changes affected the diversity and composition of small-mammal communities is mostly unknown, especially for the southern-temperate regions of Australia. We used fossil assemblages from owl regurgitates to investigate changes in small mammals from Tasmania's forest environments over the last 20,000 years, encompassing the transition from cold glacial conditions of the Last Glacial′ Maximum (LGM) into the warmer Holocene. During the early part of this period, Tasmania was connected to mainland Australia via a low-elevation land bridge, but was transformed into a large island by rising sea levels during the Late Pleistocene – Holocene transition. Despite these changes, the regional small-mammal fauna appears to have been persistent over this entire period, with no loss of species. However, the relative abundance of most species changed dramatically, apparently in response to habitat changes, which also provoked substantial shifts in community composition and diversity. A strong indicator of the magnitude of change is Mastacomys fuscus , a graminivorus specialist murid, which dominated the assemblage prior to and during the LGM, but declined as temperature and sea level rose during the Late Pleistocene – Holocene. In contrast, the generalist rodent Pseudomys higginsi , along with the small forest-dependent marsupials Cercartetus spp. and Antechinus spp., became more common during the Holocene. The continued survival of these species to the present, despite divergent environmental needs, implies that Tasmania's complex geomorphology provided multiple refugia that conferred resilience in the face of environmental change. • Last Glacial Maximum – present climate change did not cause extinctions in Tasmania. • Grassland species declined following Holocene global warming. • Forest–woodland species increased following Holocene global warming. • Species responses to Holocene global warming has conservation implications. [ABSTRACT FROM AUTHOR]

Over the last 200 years Australia has suffered the greatest rate of mammal species extinction of any continent. This demands extensive biodiversity research, but unfortunately has been hampered by poor documentation of Australia’s native species at the time of European colonization. Late-Holocene fossil mammal assemblages preserved in caves, rockshelters and surface lag deposits from deflated sand dunes can provide a more complete understanding of pre-European ecological conditions than can be developed from our knowledge of present biodiversity. In South Australia, few regions have experienced greater landscape modification and biodiversity loss than Yorke Peninsula. We investigate the composition, richness, evenness and age of two owl accumulations from southeastern and southwestern Yorke Peninsula and contrast them with a surface lag deposit assemblage probably accumulated by humans. We then examine the pre-European biogeography of the fauna recovered. The three assemblages have similar species richness, but differ dramatically in composition and evenness. The biases imposed by differing accumulation agents can explain compositional differences between owl and human assemblages, but not the differences between the respective owl accumulations. We argue that key substrate differences – one area is dominated by sand and the other by calcrete – have favoured distinct vegetation communities that fostered distinctly different mammal assemblages from which raptors accumulated prey. The ecological requirements of the extant mammals appear to be reflected in the fossil assemblages, providing support for the application of uniformitarian principles and confidence in the relevance of late-Holocene fossil assemblages to modern conservation and natural resource management. [ABSTRACT FROM AUTHOR]