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The arrival of modern humans into previously unoccupied island ecosystems is closely linked to widespread extinction, and a key reason cited for Pleistocene megafauna extinction is anthropogenic overhunting. A common assumption based on late Holocene records is that humans always negatively impact insular biotas, which requires an extrapolation of recent human behavior and technology into the archaeological past. Hominins have been on islands since at least the early Pleistocene and Homo sapiens for at least 50 thousand y (ka). Over such lengthy intervals it is scarcely surprising that significant evolutionary, behavioral, and cultural changes occurred. However, the deep-time link between human arrival and island extinctions has never been explored globally. Here, we examine archaeological and paleontological records of all Pleistocene islands with a documented hominin presence to examine whether humans have always been destructive agents. We show that extinctions at a global level cannot be associated with Pleistocene hominin arrival based on current data and are difficult to disentangle from records of environmental change. It is not until the Holocene that large-scale changes in technology, dispersal, demography, and human behavior visibly affect island ecosystems. The extinction acceleration we are currently experiencing is thus not inherent but rather part of a more recent cultural complex., Competing Interests: The authors declare no competing interest., (Copyright © 2021 the Author(s). Published by PNAS.)

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]

When pooled for extraction as a bulk sample, the DNA within morphologically unidentifiable fossil bones can, using next-generation sequencing, yield valuable taxonomic data. This method has been proposed as a means to rapidly and cost-effectively assess general ancient DNA preservation at a site, and to investigate temporal and spatial changes in biodiversity; however, several caveats have yet to be considered. We critically evaluated the bulk bone metabarcoding (BBM) method in terms of its: (i) repeatability, by quantifying sampling and technical variance through a nested experimental design containing sub-samples and replicates at several stages; (ii) accuracy, by comparing morphological and molecular family-level identifications; and (iii) overall utility, by applying the approach to two independent Holocene fossil deposits, Bat Cave (Kangaroo Island, Australia) and Finsch's Folly (Canterbury, New Zealand). For both sites, bone and bone powder sub-sampling were found to contribute significantly to variance in molecularly identified family assemblage, while the contribution of library preparation and sequencing was almost negligible. Nevertheless, total variance was small. Sampling over 80% fewer bones than was required to morphologically identify the taxonomic assemblages, we found that the families identified molecularly are a subset of the families identified morphologically and, for the most part, represent the most abundant families in the fossil record. In addition, we detected a range of extinct, extant and endangered taxa, including some that are rare in the fossil record. Given the relatively low sampling effort of the BBM approach compared with morphological approaches, these results suggest that BBM is largely consistent, accurate, sensitive, and therefore widely applicable. Furthermore, we assessed the overall benefits and caveats of the method, and suggest a workflow for palaeontologists, archaeologists, and geneticists that will help mitigate these caveats. Our results show that DNA analysis of bulk bone samples can be a universally useful tool for studying past biodiversity, when integrated with existing morphology-based approaches. Despite several limitations that remain, the BBM method offers a cost-effective and efficient way of studying fossil assemblages, offering complementary insights into evolution, extinction, and conservation. [ABSTRACT FROM AUTHOR]

This article discusses a study which examined sinkholes and rocky overhangs on the southern tip of the Eyre Peninsula, South Australia, for pre-European fossil deposits. The study analyzed the collected fossils and found five species of non-volant mammals. It found that the sites have accumulated remains of mammals in both pre- and post-European times. The study noted the implications of the findings for changes in vegetation related to European land management practices and for natural resource management in the area.

Abstract: Fossils and sediments preserved in caves are an excellent source of information for investigating impacts of past environmental changes on biodiversity. Until recently studies have relied on morphology-based palaeontological approaches, but recent advances in molecular analytical methods offer excellent potential for extracting a greater array of biological information from these sites. This study presents a thorough assessment of DNA preservation from late Pleistocene–Holocene vertebrate fossils and sediments from Kelly Hill Cave Kangaroo Island, South Australia. Using a combination of extraction techniques and sequencing technologies, ancient DNA was characterised from over 70 bones and 20 sediment samples from 15 stratigraphic layers ranging in age from >20 ka to ∼6.8 ka. A combination of primers targeting marsupial and placental mammals, reptiles and two universal plant primers were used to reveal genetic biodiversity for comparison with the mainland and with the morphological fossil record for Kelly Hill Cave. We demonstrate that Kelly Hill Cave has excellent long-term DNA preservation, back to at least 20 ka. This contrasts with the majority of Australian cave sites thus far explored for ancient DNA preservation, and highlights the great promise Kangaroo Island caves hold for yielding the hitherto-elusive DNA of extinct Australian Pleistocene species. [Copyright &y& Elsevier]