Man and megafauna in Tasmania: closing the gap

Abstract

Recent discussion on the late Pleistocene extinction of the Australian megafauna has revolved around interpretation of several key fossil sites in Tasmania. It has been suggested that humans did not arrive in Tasmania until after the megafauna became extinct, or did not hunt now extinct megafauna, and therefore that humans cannot be implicated in the extinctions. Radiocarbon results from these sites indicate that the youngest extinct megafauna are close to charcoal ages from the oldest archaeological deposits, although difficulties have arisen in establishing chronologies because most relevant sites have ages near the limit for radiocarbon analysis.We report a series of new radiocarbon ages, d 13 C, d 15 N and C:N ratios on collagen and dentine fractions from skeletal remains in the Mount Cripps karst area and the Mowbray Swamp, both in northwestern Tasmania, and discuss the reliability of ages from these and other sites. We also report the discovery of an articulated Simosthenurus occidentalis skeleton at Mt Cripps, that represents only the second directlydated extinct megafaunal taxon with a reliable age <50 ka cal BP from Tasmania.Our results suggest that C:N ratios measured on collagen or dentine are not an infallible guide to radiocarbon age reliability. We confirm previous reports of a temporal overlap between the megafaunal and archaeological records in Tasmania, but the presence of archaeological evidence and megafauna with the same age at the same site has not yet been demonstrated. At least two megafaunal taxadthe nowextinct Protemnodon anak and a giant Pleistocene form of the extant Macropus giganteusdwere still present in Tasmania after 43 ka, when human crossing of the Bassian landbridge from mainland Australia first became sustainable.

New 14C dates for Spring Creek and Mowbray Swamp megafauna: XAD‐2 processing

“…Previous 14 C results on various collagen/gelatin fractions prepared from Zygomaturus trilobus and Palorchestes azael bones were scattered and considered unreliable by Gillespie et al . (). Based on geological data, Gill and Banks () suggested that the deposit containing the bones was >75 ka; radiocarbon ages on wood, marl and peat recovered from Mowbray Swamp (and similar fossiliferous deposits at the nearby Pulbeena Swamp) were consistently >50000 BP (Banks et al .…”

“… Uncalibrated radiocarbon ages on XAD ‐2 purified total amino acid fractions (black solid circles) measured on extinct marsupials in this study, compared with previous results on collagen or gelatin (open circles, W hite & F lannery ) or ultrafiltered gelatin (grey‐filled circles, G illespie et al . ). …”

“…The Protemnodon anak bone sample MCP‐2 processed for this work yielded an age on XAD‐2 purified amino acids of 42600 ± 1800 BP (UCIAMS‐116399), which is statistically identical at 95% confidence ( T = 2.37, Ξ 2 = 5.99, 2 dof, using the CALIB 6 program) with the two ultrafiltered gelatin results on the same bone reported by Gillespie et al . ().…”

“…(), ultrafiltered gelatin from extinct marsupials found in the Mowbray Swamp, north‐western Tasmania, produced dark‐coloured gelatin that failed to deliver the expected background ages (Gillespie et al . ).…”

Soil or fire: what causes treeless sedgelands in Tasmanian wet forests?

“…Recent research there has shown that the combination of ecohydrological drought (exacerbate by anthropogenic soil drainage) and fire can cause the state change from rainforest to shrubland because the upper profile of organic soils are destroyed Taufik et al 2017). Also, unlike most tropical savannas (e.g., Skarpe 1992), no substantial populations of large herbivores graze on the Tasmanian sedgelands: whether the extinct Pleistocene marsupial megafauna (Gillespie et al 2012) were important in shaping the ecology (e.g., Gill 2014; Rule et al 2012) in this ecosystem is unknown.…”