9 research outputs found
A diverse Pleistocene marsupial trackway assemblage from the Victorian Volcanic Plains, Australia
No full textStephen P. Carey, Aaron B. Camens, Matthew L. Cupper, Rainer Grün, John C. Hellstrom, Stafford W. McKnight, Iain Mclennan, David A. Pickering, Peter Trusler and Maxime Auberthttp://www.journals.elsevier.com/quaternary-science-reviews
The timing and cause of megafauna mass deaths at Lancefield Swamp, south-eastern Australia
No full textLancefield 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
The Willandra Fossil Trackway: Assessment of ground penetrating radar survey results and additional OSL dating at a unique Australian site
No full textThis paper presents some results of a ground penetrating radar survey conducted to establish the extent of the Willlandra Fossil Trackway, and further mapping of the footprints and intermingled tracks. In addition, it includes a refinement of the age range of the trackway, through further OSL dating, to between 19,000 and 20,000 years ago. Finally, it also provides a discussion of the geochemical composition of the trackway
The Willandra Fossil Trackway: Assessment of ground penetrating radar survey results and additional OSL dating at a unique Australian site
No full textThis paper presents some results of a ground penetrating radar survey conducted to establish the extent of the Willlandra Fossil Trackway, and further mapping of the footprints and intermingled tracks. In addition, it includes a refinement of the age range of the trackway, through further OSL dating, to between 19,000 and 20,000 years ago. Finally, it also provides a discussion of the geochemical composition of the trackway.Griffith Sciences, Griffith School of EnvironmentFull Tex
Holocene climate change in arid Australia from speleothem and alluvial records
No full text New high-resolution MC-ICPMS U/Th ages and C and O isotopic analyses from a Holocene speleothem in arid south-central Australia provide evidence for increased effective precipitation (EP) relative to present at c. 11.5 ka and c. 8—5 ka, peak moisture at 7—6 ka, and onset of an arid climate similar to present by c. 5 ka. δ18O and δ13C time-series data exhibit marked (>+1‰) contemporaneous excursions over base-line values of −5.3‰ and −11.0‰, respectively, suggesting pronounced moisture variability during the early middle Holocene ‘climatic optimum’. Optically stimulated luminescence and 14C ages from nearby terraced aggradational alluvial deposits indicate a paucity of large floods in the Late Pleistocene and at least five large flood events in the last c. 6 kyr, interpreted to mark an increased frequency of extreme rainfall events in the middle Holocene despite overall reduced EP. Increased EP in south-central Australia during the early to middle Holocene resulted from (1) decreased El Niño-Southern Oscillation (ENSO) variability, which reduced the frequency of El Niño-triggered droughts, (2) the prevalence of a more La Niña-like mean climatic state in the tropical Pacific Ocean, which increased available atmospheric moisture, and (3) a southward shift in the Intertropical Convergence Zone (ICTZ), which allowed tropical summer storms associated with the Australian summer monsoon (ASM) to penetrate deeper into the southern part of the continent. The onset of heightened aridity and apparent increase in large flood frequency at c. 5 ka is interpreted to indicate the establishment of an ENSO-like climate in arid Australia in the late Holocene, consistent with a variety of other terrestrial and marine proxies. The broad synchroneity of Holocene climate change across much of the Australian continent with changes in ENSO behavior suggests strong teleconnections amongst ENSO and the other climate systems such as the ASM, Indian Ocean Dipole, and Southern Annular Mode. </jats:p
Do weak or strong acids remove carbonate contamination from ancient tooth enamel more effectively? The effect of acid pretreatment on radiocarbon and δ13C analyses
No full textIn hot environments collagen, which is normally targeted when radiocarbon dating bone, rapidly degrades. With little other skeletal material suitable for radiocarbon dating, it can be impossible to obtain dates directly on skeletal materials. A small amount of carbonate occurs in hydroxyapatite, the mineral phase of bone and tooth enamel, and has been used as an alternative to collagen. Unfortunately, the mineral phase is often heavily contaminated with exogenous carbonate causing radiocarbon dates to underestimate the true age of a sample. Although tooth enamel, with its larger, more stable crystals and lower porosity, is likely to be more robust to diagenesis than bone, little work has been undertaken to investigate how exogenous carbonate can be effectively removed prior to radiocarbon dating. Typically, acid is used to dissolve calcite and etch the surface of the enamel, but it is unclear which acid is most effective. This study repeats and extends earlier work using a wider range of samples and acids and chelating agents (hydrochloric, lactic, acetic and propionic acids, and EDTA). We find that weaker acids remove carbonate contaminants more effectively than stronger acids, and acetic acid is the most effective. However, accurate dates cannot always be obtained.The research and R. Wood were funded by an Australian Research Council DECRA fellowship (DE150100070). Infrared spectral analyses were supported by Australian Research Council grants to Penelope L King (DP15014606 and FT130101524) and ANU Major Equipment Committee grants to Jörg Hermann and John Mavrogenes. Jaime Swift, Matthew Cupper, Rainer Grun, Malte Willmes and Hannah James are thanked for providing the modern pig teet
Skeletal arsenic of the pre-Columbian population of Caleta Vitor, northern Chile
No full textExposure to toxic arsenic has severe health consequences for past and present societies. This research resolves changes in a pre-Industrial population's exposure to the toxin within an arsenic-endemic area of the Atacama Desert of northern Chile over long timescales. Inductively coupled plasma mass spectrometry (ICP-MS) trace element analysis of human bone and tooth samples from 21 burials at Caleta Vitor on the Pacific coast of northern Chile has established that the pre-Columbian inhabitants were exposed to elevated levels of arsenic where one third of the sample population had accumulated levels in their skeletal system indicative of chronic poisoning. Coupled with new accelerator mass spectrometry (AMS) radiocarbon ages for the skeletal samples, spanning c. 3867 to 474 cal BP and encompassing all major cultural periods of the region, these results demonstrate the continual risk of arsenic poisoning over several millennia of occupation at one site. Numerous factors may have partially contributed to the population's inferred poisoning, due to the complex interaction of various environmental sources of arsenic and human behaviours. Increased exposure to arsenic could relate to climatic variability influencing sources of drinking water or anthropogenic activities such as mining and metallurgy or dietary changes associated with agriculture. Assessment of these potential sources of arsenic toxication, including evaluation of modern environmental data from the region, suggests contaminated drinking water was the most likely cause of arseniasis
Skeletal arsenic of the pre-Columbian population of Caleta Vitor, northern Chile
No full textExposure to toxic arsenic has severe health consequences for past and present societies. This research resolves changes in a pre-Industrial population's exposure to the toxin within an arsenic-endemic area of the Atacama Desert of northern Chile over long timescales. Inductively coupled plasma mass spectrometry (ICP-MS) trace element analysis of human bone and tooth samples from 21 burials at Caleta Vitor on the Pacific coast of northern Chile has established that the pre-Columbian inhabitants were exposed to elevated levels of arsenic where one third of the sample population had accumulated levels in their skeletal system indicative of chronic poisoning. Coupled with new accelerator mass spectrometry (AMS) radiocarbon ages for the skeletal samples, spanning c. 3867 to 474 cal BP and encompassing all major cultural periods of the region, these results demonstrate the continual risk of arsenic poisoning over several millennia of occupation at one site. Numerous factors may have partially contributed to the population's inferred poisoning, due to the complex interaction of various environmental sources of arsenic and human behaviours. Increased exposure to arsenic could relate to climatic variability influencing sources of drinking water or anthropogenic activities such as mining and metallurgy or dietary changes associated with agriculture. Assessment of these potential sources of arsenic toxication, including evaluation of modern environmental data from the region, suggests contaminated drinking water was the most likely cause of arseniasis.No Full Tex
An arid-adapted middle Pleistocene vertebrate fauna from south-central Australia
No full textHow well the ecology, zoogeography and evolution of modern biotas is understood depends substantially on knowledge of the Pleistocene1, 2. Australia has one of the most distinctive, but least understood, Pleistocene faunas. Records from the western half of the continent are especially rare3. Here we report on a diverse and exceptionally well preserved middle Pleistocene vertebrate assemblage from caves beneath the arid, treeless Nullarbor plain of south-central Australia. Many taxa are represented by whole skeletons, which together serve as a template for identifying fragmentary, hitherto indeterminate, remains collected previously from Pleistocene sites across southern Australia. A remarkable eight of the 23 Nullarbor kangaroos are new, including two tree-kangaroos. The diverse herbivore assemblage implies substantially greater floristic diversity than that of the modern shrub steppe, but all other faunal and stable-isotope data indicate that the climate was very similar to today. Because the 21 Nullarbor species that did not survive the Pleistocene were well adapted to dry conditions, climate change (specifically, increased aridity) is unlikely to have been significant in their extinction
