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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. [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]

Over the last 200 years Australia has suffered the greatest rate of mammal species extinction of any continent. This demands extensive biodiversity research, but unfortunately has been hampered by poor documentation of Australia’s native species at the time of European colonization. Late-Holocene fossil mammal assemblages preserved in caves, rockshelters and surface lag deposits from deflated sand dunes can provide a more complete understanding of pre-European ecological conditions than can be developed from our knowledge of present biodiversity. In South Australia, few regions have experienced greater landscape modification and biodiversity loss than Yorke Peninsula. We investigate the composition, richness, evenness and age of two owl accumulations from southeastern and southwestern Yorke Peninsula and contrast them with a surface lag deposit assemblage probably accumulated by humans. We then examine the pre-European biogeography of the fauna recovered. The three assemblages have similar species richness, but differ dramatically in composition and evenness. The biases imposed by differing accumulation agents can explain compositional differences between owl and human assemblages, but not the differences between the respective owl accumulations. We argue that key substrate differences – one area is dominated by sand and the other by calcrete – have favoured distinct vegetation communities that fostered distinctly different mammal assemblages from which raptors accumulated prey. The ecological requirements of the extant mammals appear to be reflected in the fossil assemblages, providing support for the application of uniformitarian principles and confidence in the relevance of late-Holocene fossil assemblages to modern conservation and natural resource management. [ABSTRACT FROM AUTHOR]