Quaternary record of aridity and mean annual precipitation based on δ[sup.15]N in ratite and dromornithid eggshells from Lake Eyre, Australia

• Published in: Oecologia 2011-12, Vol.167 (4), p.1151
• Main Authors: Newsome, Seth D, Miller, Gifford H, Magee, John W, Fogel, Marilyn L
• Format: Article
• Language: English
• Subjects: Ecosystems; Fossils; Nitrogen; Rain and rainfall
• ISSN: 0029-8549; 1432-1939
• DOI: 10.1007/s00442-011-2046-5

The cause(s) of the late Pleistocene megafauna extinction on the Australian continent remains largely unresolved. Unraveling climatic forcing mechanisms from direct or indirect human agents of ecosystem alteration has proven to be extremely difficult in Australia due to the lack of (1) well-dated vertebrate fossils and (2) paleo-environmental and -ecological records spanning the past approximately 100 ka when regional climatic conditions are known to have significantly varied. We have examined the nitrogen isotope composition (d N) of modern emu (Dromaius novaehollandiae) eggshells collected along a precipitation gradient in Australia, along with modern climatological data and dietary d N values. We then used modern patterns to interpret an approximately 130-ka record of δ[sup.15]N values in extant Dromaius and extinct Genyornis newtoni eggshells from Lake Eyre to obtain a novel mean annual precipitation (MAP) record for central Australia spanning the extinction interval. Our data also provide the first detailed information on the trophic ecology and environmental preferences of two closely related taxa, one extant and one extinct. Dromaius eggshell δ[sup.15]N values show a significant shift to higher values during the Last Glacial Maximum and Holocene, which we interpret to indicate more frequent arid Conditions (