New 14 C dates for Spring Creek and Mowbray Swamp megafauna: XAD-2 processing.

Bones from extinct Australian marsupials found at Spring Creek, Victoria, and in the Mowbray Swamp, Tasmania, have yielded scattered and anomalously young radiocarbon ages measured on collagen, gelatin or ultrafiltered gelatin. We resampled previously dated material from those two sites and from Mt Cripps, Tasmania, as well as a control sample from Zaglik, Russia, to compare chronologies based on XAD-2 purified total amino acid fractions and collagen purified by ultrafiltration ( UF) or less rigorous methods. Our age from the control site bone gave a similar infinite age, while six out of seven other comparisons yielded radiocarbon ages on total amino acid fractions older than those previously measured on collagen or gelatin. The Palorchestes from Spring Creek yielded a date of >53500 BP. [ABSTRACT FROM AUTHOR]