Search

We use fossil, sub‐fossil and contemporary records of the Broad‐toothed rat, Mastacomys fuscus, to model changes in its range over the last 21 thousand years. Mastacomys fuscus was exposed to, and flourished in, a much broader range of environmental conditions in the recent past than it occupies today. It also currently occupies a much smaller range than it did in the Late Pleistocene. Apart from a weak response to sea‐level rise in the Holocene, the decline of M. fuscus does not correlate with known climate change. Instead, the contraction of the species' distribution on mainland Australia to high‐elevation areas occurred recently and rapidly. Small changes in the 1000 year BP and present‐day projected distributions imply some contraction of the area of suitable climate to higher elevations of the mainland subspecies M. f. mordicus, up to 2200 m above sea level. However, M. f. mordicus also persists near sea level at Cape Otway (southwestern Victoria) and from sea level to 1500 m above sea level at Barrington Tops (eastern New South Wales, Australia). This suggests suitable habitat may still exist in coastal Victoria and the central Tablelands/Blue Mountains areas. This research highlights the importance and value of using sub‐fossil data to understand changes in the distribution and niche occupation of threatened species as the basis for conservation planning. [ABSTRACT FROM AUTHOR]

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]

Extinctions stemming from environmental change often trigger trophic cascades and coextinctions. Bottom–up cascades occur when changes in the primary producers in a network elicit flow‐on effects to higher trophic levels. However, it remains unclear what determines a species' vulnerability to bottom–up cascades and whether such cascades were a large contributor to the megafauna extinctions that swept across several continents in the Late Pleistocene. The pathways to megafauna extinctions are particularly unclear for Sahul (landmass comprising Australia and New Guinea), where extinctions happened earlier than on other continents. We investigated the potential role of bottom–up trophic cascades in the megafauna extinctions in Late Pleistocene Sahul by first developing synthetic networks that varied in topology to identify how network position (trophic level, diet breadth, basal connections) influences vulnerability to bottom–up cascades. We then constructed pre‐extinction (~80 ka) network models of the ecological community of Naracoorte, south‐eastern Sahul, to assess whether the observed megafauna extinctions could be explained by bottom–up cascades. Synthetic networks showed that node vulnerability to bottom–up cascades decreased with increasing trophic level, diet breadth and basal connections. Extinct species in the Naracoorte community were more vulnerable overall to these cascades than were species that survived. The position of extinct species in the network – tending to be of low trophic level and therefore having relatively narrow diet breadths and fewer connections to plants – made them vulnerable. However, these species also tended to have few or no predators, a network‐position attribute that suggests they might have been particularly vulnerable to new predators. Together, these results suggest that trophic cascades and naivety to predators could have contributed to the megafauna extinction event in Sahul. [ABSTRACT FROM AUTHOR]

ABSTRACT It is widely accepted that most larger Australian vertebrates were extinct by 40 ka. The reliability of <20-ka radiocarbon (14C) ages on charcoal stratigraphically associated with sthenurine (short-faced) kangaroo tooth fragments from Seton Rockshelter, Kangaroo Island, have therefore proven contentious. Some researchers have argued these fossils were in situ, while others have claimed they were reworked. To address this we obtained new 14C ages on bones from the site. These bone ages are not only consistent with earlier charcoal ages, but are in near-perfect stratigraphic order, providing strong support for the site's stratigraphic integrity. Our analyses indicate units aged 21−17 ka were primarily accumulated by Tasmanian devils ( Sarcophilus harrisii) and owls ( Tyto species), after which humans became the primary accumulation agent. The tight chronology, faunal trends and current lack of evidence for older layers from which specimens could have been reworked suggest the sthenurine remains may be in situ. However, because attempts to directly date sthenurine material failed, we cannot confidently assert that they survived to this time. Therefore, Seton Rockshelter may be best excluded from the Pleistocene extinction debate until the site can be re-excavated and more conclusive evidence collected, including more complete or directly datable sthenurine remains. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

European-settlement-related impacts over the past 200 years pose many challenges for the conservation and restoration of Australia's ecosystems. Landscape modification, associated habitat loss and the introduction of exotic species have caused the extinction and mainland extirpation of numerous vertebrates. This process happened so quickly that many species became locally or functionally extinct before their presence was documented. A growing body of research on Holocene fossil accumulations is providing insights into the composition and biogeography of Australian ecosystems prior to European settlement. This review explores the similarities between palaeo- and neo-ecology and how Holocene (last 10,000 years) assemblages can be used by neo-ecologists, conservation managers and policy makers to identify and fill gaps in knowledge and contribute to the management and restoration of Australia's degraded ecosystems. [ABSTRACT FROM AUTHOR]

Chronological, sedimentological and geochemical analyses of a clastic infill from Kelly Hill Cave ( 5K1), Kangaroo Island, document a palaeoenvironmental record that spans from the Late Pleistocene to the middle Holocene. We AMS radiocarbon-dated bone collagen and U- Th-dated speleothem to determine that fossiliferous sediments were deposited between >20 ka and 7 ka ago. Most of the 15 sedimentary layers are dominated by sand- and silt-sized quartz that is physically and geochemically comparable with surface soils in the Kelly Hill area. Late Pleistocene and Last Glacial Maximum strata are represented primarily by homogeneous, poorly sorted quartz-rich sediments that contain little organic matter, but include a thin layer composed largely of silt-sized clay pellets that resemble sediments deflated from playa lakes. Microstructures observed in petrographic slides indicate that, with the exception of one layer, all sediments experienced little reworking once deposited in the cave. Some layers display pedogenic microstructures such as redeposited clays and opaline silica infilling that indicate postdepositional modification; that is, cave-floor soil development. Overlying Holocene-aged sediments also consist mainly of quartz but have much greater organic matter content. Some of these sediments have been strongly influenced by re-precipitated organic matter that appears to have been transported into the cave via vadose drip water. The presence of dissolved organic matter in soil/vadose waters suggests a high vegetation density and acidic soils, which are congruent with the more equitable climatic conditions characteristic of the Holocene. The sediments described here provide a valuable palaeoenvironmental record that will facilitate future interpretation of associated vertebrate fossils. [ABSTRACT FROM AUTHOR]