Annual rainfall and nitrogen-isotope correlation in macropod collagen: application as a palaeoprecipitation indicator

Collagen has been extracted and analysed for δ15N from modern kangaroos, macropods (Macropus eugenii, M. antilopinus, M. fuliginosus, M. rufus, M. robustus), in Western Australia and South Australia. Comparison of nitrogen-isotope ratios with annual rainfall for the respective areas produced a good negative correlation for macropods, but not for other marsupials. This may be related to metabolic adaptations in macropods to compete against water loss. Hence, the correlation between δ15N and annual rainfall may be species-specific. Nitrogen-isotope analyses on collagenic material extracted from fossil macropods (Macropus spp.) have been determined from two Late Pleistocene deposits in South Australia. Corroboration with spore-pollen and sedimentological data confirm that δ15N of collagenic material can be used as a proxy for palaeoprecipitation levels in Australia. This has great potential for understanding palaeoclimatic changes, especially drought periods, in Australia during the Pleistocene.