Publications by authors named "Eric A Colhoun"

2 Publications

  • Page 1 of 1

Late-surviving megafauna in Tasmania, Australia, implicate human involvement in their extinction.

Proc Natl Acad Sci U S A 2008 Aug 21;105(34):12150-3. Epub 2008 Aug 21.

GeoQuEST Research Centre, School of Earth and Environmental Sciences, University of Wollongong, Wollongong NSW 2522, Australia.

Establishing the cause of past extinctions is critical if we are to understand better what might trigger future occurrences and how to prevent them. The mechanisms of continental late Pleistocene megafaunal extinction, however, are still fiercely contested. Potential factors contributing to their demise include climatic change, human impact, or some combination. On the Australian mainland, 90% of the megafauna became extinct by approximately 46 thousand years (ka) ago, soon after the first archaeological evidence for human colonization of the continent. Yet, on the neighboring island of Tasmania (which was connected to the mainland when sea levels were lower), megafaunal extinction appears to have taken place before the initial human arrival between 43 and 40 ka, which would seem to exonerate people as a contributing factor in the extirpation of the island megafauna. Age estimates for the last megafauna, however, are poorly constrained. Here, we show, by direct dating of fossil remains and their associated sediments, that some Tasmanian megafauna survived until at least 41 ka (i.e., after their extinction on the Australian mainland) and thus overlapped with humans. Furthermore, a vegetation record for Tasmania spanning the last 130 ka shows that no significant regional climatic or environmental change occurred between 43 and 37 ka, when a land bridge existed between Tasmania and the mainland. Our results are consistent with a model of human-induced extinction for the Tasmanian megafauna, most probably driven by hunting, and they reaffirm the value of islands adjacent to continental landmasses as tests of competing hypotheses for late Quaternary megafaunal extinctions.
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http://dx.doi.org/10.1073/pnas.0801360105DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2527880PMC
August 2008

Interglacial pollen and plant macrofossils from Langdon River, western Tasmania.

New Phytol 1989 Mar;111(3):531-548

CSIRO, Stowell Avenue, Hobart, Tas, 7000, Australia.

Pollen and plant macrofossils from Langdon liner give an interglacial floral record for western Tasmania. The location of the site between the ice limits of the Last or Margaret Glaciation and the Penultimate or Henty Glaciation indicate that it cannot be younger than the Last Interglacial. The sequence of vegetation changes shows the succession Casuarina Phyllocladus-Nothofagus with Casuarina as pioneer and Nothofagus as representing Maximum wet forest development. After the maximum the presence of Phyllocladus-Nothofagus-Eucalyptus-Microstrobos suggests deterioration to subalpine woodland/shrubland, and Compositae, Gramineae-Microstrobos to alpine shrubland and herbland. The sequence represents most of a glacial-interglacial-glacial cycle Of environmental changes that occurred before 43 000 C yr B.P. Very high Casuarina values occur in the early part at the interglacial sequence which contrasts with the Holocene where Eucalyptus is more important than Casuarina. Otherwise the sequence of Phyllocladus, Nothofagus, Eucryphia-Anodopetalum is the same as for Holocene forest development. The interglaeial 'optimum' is marked by the occurrence of Pomaderris apetala type and Dicksonia antarctica. There is some similarity with the Casuarina curves in the Lake George interglacials before the Last Interglacial. But, on the whole, there is more similarity with interglacial rainforest development in western South Island, New Zealand Only one cycle of vegetation change is recognized at Langdon River which is unlike New Zealand and central Chilean records from 40-42° S which in different ways record a mid Last Interglacial climatic deterioration.
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http://dx.doi.org/10.1111/j.1469-8137.1989.tb00716.xDOI Listing
March 1989