Dr Peter Murray
- Ass. Director Curatorial Services, Museum of Central Australia
- Dr Peter Murray gives his view on the Australian megafaunal extinctions
Peter Murray's research concentrates on the reconstruction of Late Tertiary land vertebrate faunas of Australia. Refinement of the biochronology of central Australian faunas over the past 15 million years is an essential aim of the work and extinction phenomena are considered from relatively broad temporal and contextual perspectives.
"Australia's unique tertiary vertebrate fauna evolved in comparative isolation, with no clear evidence of major external disturbances in species diversity and community structure until the late Pleistocene. Between 50,000-100,000 years ago, all browsing marsupials and flightless birds that weighed more than 40kg became extinct. A good many smaller vertebrates of all dietary persuasions have since disappeared.
"Explanation for the general pattern is vividly clear. Nutrient-poor soils and decreasing rainfall left the Australian continent dominated by tough-leafed flora. This was low in nutritional value, though adequate fodder if consumed in large quantities. Terrestrial marsupial herbivores and flightless dromornithid birds responded by increasing body mass.
"Dry heat enabled wildfires to spread from the grassland into surrounding woodlands, expanding the area available for grasses and shrubs and perpetuating the cycle. Kangaroos increased in response, while fire resistant species such as eucalyptus began to replace some of the fire sensitive flora.
"The fruit, flowers, leaves, vines, nuts and pods that would have sustained browsing megafauna have shrunk into fire shadows or survive as isolated species in ravines, crevices and on outcrops - sufficient food only for small creatures. Consequently, I consider the extremely rapid and consummate transformation of the Australian flora by human burning practices to be the fundamental cause of Late Pleistocene megafaunal extinction in Australia."
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