Micro Methods for Megafauna: Novel Approaches to Late Quaternary Extinctions and Their Contributions to Faunal Conservation in the Anthropocene

Drivers of Late Quaternary megafaunal extinctions are relevant to modern conservation policy in a world of growing human population density, climate change, and faunal decline. Traditional debates tend toward global solutions, blaming either dramatic climate change or dispersals of Homo sapiens to new regions. Inherent limitations to archaeological and paleontological data sets often require reliance on scant, poorly resolved lines of evidence. However, recent developments in scientific technologies allow for more local, context-specific approaches. In the present article, we highlight how developments in five such methodologies (radiocarbon approaches, stable isotope analysis, ancient DNA, ancient proteomics, microscopy) have helped drive detailed analysis of specific megafaunal species, their particular ecological settings, and responses to new competitors or predators, climate change, and other external phenomena. The detailed case studies of faunal community composition, extinction chronologies, and demographic trends enabled by these methods examine megafaunal extinctions at scales appropriate for practical understanding of threats against particular species in their habitats today. </section

Large mammal species richness and late Quaternary precipitation change in south-western Australia

The precipitation history of south-west Australia since the Last Glacial Maximum (LGM) has important implications for understanding southern hemisphere climate dynamics. Previously reported environmental records indicating more open vegetation during the LGM have been interpreted in terms of aridity, but such changes can be explained by alternative mechanisms. To provide new evidence concerning the region's Quaternary precipitation history, we examine temporal changes in large mammal richness at four south-west Australian fossil sites: Devil's Lair, Tunnel Cave, Witchcliffe Rock Shelter and Rainbow Cave. Large mammal richness is correlated strongly with mean annual precipitation across 53 modern Australian communities. Extending this relationship to the fossil record, a steady increase in richness from the LGM to the onset of the Holocene at both Devil's Lair and Tunnel Cave is consistent with increased precipitation through time. This supports previous interpretations of a more arid LGM and implies regional heterogeneity in the position of the southern hemisphere westerlies. A reduction in richness during the last ∼1000 years is unlikely to be the result of precipitation change and may be related to more frequent burning of the landscape by hunter-gatherers in an effort to increase availability of large prey

Settling the West: 50 000 years in a changing land

Australia was first colonised more than two thousand human generations ago. In this paper we show how, over this period, ancestors of Western Australia's Aboriginal peoples adapted to changing environments, in tropical savannahs, deserts, woodlands, forests and coastlines. Throughout this history, there is evidence for intra-regional genetic and economic continuities, and exchanges and dynamism in religion, language and art. These relationships are remarkably well- documented in Western Australia, which features many of the oldest sites on the continent. The evidence reviewed here derives from the Kimberley, Western Desert, Pilbara and South West. Each region contains at least one site first occupied c. 50 000 years ago, and numerous other sites first occupied in the late Pleistocene. We describe the archaeological evidence for the early development of a range of complex modern behaviour from each region, including symbolic behaviour, information exchange, ground-stone technology, and ecosystem engineering. We also address the apparent tension between regional continuity and inter-regional contact and exchange.We also thank the Australian Research Council for funding the research through LP140100393 Murujuga: Dynamics of the Dreaming; DP130100802 Barrow Island Archaeological Project; LP100200415 Lifeways of the First Australians; FT100100206 Rock Art of the Western Desert & Great Basin; LP0776332 Rock art and related dreaming (Jukurrpa) sites on the Canning Stock Route, Western Australia; and LP0669233 Aboriginal Landscape Transformations. Funding was also generously provided by Kimberley Foundation Australia, Rio Tinto and Atlas Iron

The timing and cause of megafauna mass deaths at Lancefield Swamp, south-eastern Australia

Lancefield Swamp, south-eastern Australia, was one of the earliest sites to provoke interest in Pleistocene faunal extinctions in Sahul (Pleistocene Australia-New Guinea). The systematic investigation of the deposit in the early 1970s identified megafaunal remains dominated by the 100–200 kg kangaroo Macropus giganteus titan. Associated radiocarbon ages indicated that the species was extant until c.30,000 BP, suggesting significant overlap with human settlement of Sahul. This evidence was inconsistent with contemporary models of rapid human-driven extinctions. Instead, researchers inferred ecological tethering of fauna at Lancefield Swamp due to intense drought precipitated localised mass deaths, consistent with Late Pleistocene climatic variability. Later investigations in another part of the swamp, the Mayne Site, remote to the initial investigations, concluded that mass flow disturbed this area, and Electron Spin Resonance (ESR) analyses on megafauna teeth returned wide-ranging ages. To clarify site formation processes and dating of Lancefield Swamp, we excavated new test-pits next to previous trenches in the Classic and Mayne Sites. We compared absolute chronologies for sediments and teeth, sedimentology, palaeo-topography, taphonomy, and macropod age at death across the swamp. Luminescence dating of sediments and ESR analysis of teeth returned ages between c.80,000 and 45,000 years ago. We found no archaeological remains in the bone beds, and evidence of carnivore activity and fluvial action, in the form of reactivated spring flow. The latter disturbed limited parts of the site and substantial areas of the bone beds remained intact. The faunal assemblage is dominated by megafaunal adult Macropus, consistent with mass die-offs due to severe drought. Such droughts appear to have recurred over millennia during the climatic variability of Marine Isotope Stages 4 and 3. These events began tens of millennia before the first appearance of Aboriginal people in Sahul and only the very youngest fossil deposits could be coeval with the earliest human arrivals. Therefore, anthropogenic causes cannot be implicated in most if not all of mass deaths at the site. Climatic and environmental changes were the main factors in site formation and megafauna deaths at Lancefield Swamp.We thank members of the Wurundjeri Tribe Land and Heritage Council for the endorsement of our research, which was funded by the Australian Research Council (ARC DP0342843), a University of Sydney Sesquicentenary R&D Grant held by JD, and a Carlyle Greenwell Bequest to BN. We are grateful for the support of the Lancefield Park Management Committee, Office of Aboriginal Affairs Victoria, Department of Environment, Land, Water and Planning (Vic.) and Shire of Macedon Ranges

Prolonged coexistence of humans and megafauna in Pleistocene Australia

Recent claims for continent wide disappearance of megafauna at 46.5 thousand calendar years ago (ka) in Australia have been used to support a "blitzkrieg" model, which explains extinctions as the result of rapid overkill by human colonizers. A number of key sites with megafauna remains that significantly postdate 46.5 ka have been excluded from consideration because of questions regarding their stratigraphic integrity. Of these sites, Cuddie Springs is the only locality in Australia where megafauna and cultural remains are found together in sequential stratigraphic horizons, dated from 36-30 ka. Verifying the stratigraphic associations found here would effectively refute the rapid-overkill model and necessitate reconsideration of the regional impacts of global climatic change on megafauna and humans in the lead up to the last glacial maximum. Here, we present geochemical evidence that demonstrates the coexistence of humans and now-extinct megafaunal species on the Australian continent for a minimum of 15 ka

Data from: Genetic diversity and drivers of dwarfism in extinct island emu populations

Australia’s iconic emu (Dromaius novaehollandiae novaehollandiae) is the only living representative of its genus, but fossil evidence and reports from early European explorers suggest that three island forms (at least two of which were dwarfs) became extinct during the 19th century. While one of these - the King Island emu - has been found to be conspecific with Australian mainland emus, little is known about how the other two forms - Kangaroo Island and Tasmanian emus - relate to the others, or even the size of Tasmanian emus. We present a comprehensive genetic and morphological analysis of Dromaius diversity, including data from one of the few definitively genuine Tasmanian emu specimens known. Our genetic analyses suggest that all the island populations represent sub-populations of mainland D. novaehollandiae. Further, the size of island emus and those on the mainland appears to scale linearly with island size but not time since isolation, suggesting that island size—and presumably concomitant limitations on resource availability—may be a more important driver of dwarfism in island emus, though its precise contribution to emu dwarfism remains to be confirmed

Data from: Genetic diversity and drivers of dwarfism in extinct island emu populations

Australia’s iconic emu (Dromaius novaehollandiae novaehollandiae) is the only living representative of its genus, but fossil evidence and reports from early European explorers suggest that three island forms (at least two of which were dwarfs) became extinct during the 19th century. While one of these - the King Island emu - has been found to be conspecific with Australian mainland emus, little is known about how the other two forms - Kangaroo Island and Tasmanian emus - relate to the others, or even the size of Tasmanian emus. We present a comprehensive genetic and morphological analysis of Dromaius diversity, including data from one of the few definitively genuine Tasmanian emu specimens known. Our genetic analyses suggest that all the island populations represent sub-populations of mainland D. novaehollandiae. Further, the size of island emus and those on the mainland appears to scale linearly with island size but not time since isolation, suggesting that island size—and presumably concomitant limitations on resource availability—may be a more important driver of dwarfism in island emus, though its precise contribution to emu dwarfism remains to be confirmed