Archaeol. Oceania 39 (2004) 50-51 Research Reports Stable isotope and protein analyses of Cuddie Springs Genyornis J. BRENNER COLTRAIN, J. FIELD, R. COSGROVE AND J. O'CONNELL Abstract Stable isotopes and proteins in Genyomis remains from Cuddie Springs are too depleted for dating, but this does not imply the bones are olderthan surrounding sediments. Excavations at Cuddie Springs (northern New South Wales) have yielded remains of Diprotodon, Genyornis, Procoptodon, Protemnodon, Pallimnarchus and Sthenurus from sediments dated by calibrated radiocarbon and luminescence at 30-37 ka BP (Field and Dodson, 1999; Field et al., 2001, 2002). If valid, these data counter the proposition that Sahul megafauna disappeared well before 40 ka BP, possibly as a result of human overkill (Miller et al., 1999; Roberts et al., 2001). Those favoring the overkill argument claim the association between bones and dates is secondary, the bones having been re-deposited from much older sediments (Gillespie and David, 2001; Roberts, 2001; Roberts et al., 2001). One way of resolving this issue is by directly dating the bones. Six samples of Genyornis were selected for possible radiocarbon analysis (Table I). All were drawn from Stratigraphic Unit 6b, a 30 ern thick deposit of silts and clays that also yielded examples of Diprotodon, Protemnodon, and Sthenurus (Field and Dodson, 1999). Associated radiocarbon dates (five AMS, two ABOX-SC, one conventional) are in the range 29-34 ka BP (32.7-36.4 ka CAL [Gillespie, 1998]); two luminescence dates are reported as 35.4 ka BP (Field and Dodson, 1999) and 36 ka BP (Roberts et al., 2001). Analyses All samples were prepared using a standard protocol (described on-line at <http://www.anthro.utah.edu/papers. html». Prior to treatment, about one milligram of whole bone from each sample was powdered and analyzed for JBe, JFO'C: Dept of Anthropology, University of Utah, Salt Lake City, USA 84112;JF: Dept of Archaeology, University of Sydney, NSW 2006 Australia; RC: School of Archaeology, La Trobe University, BundooraVic 3083, Australia 50 nitrogen (whole bone %N), providing an initial indication of protein preservation. Modem bone contains about 4% N by weight; archaeological samples with as little as 0.2% N have yielded reliable dates (Stafford et al., 1991). Five of the six Cuddie Springs samples contained too little nitrogen to be detected. The sixth, CGS1037A (ACRF-236), measured 3.08% N by weight. Subsequent efforts to isolate collag- enous proteins reduced all samples to <I % of their initial weights. Modem bone is approximately 25% collagenous protein. Extremely low collagen yields in all six samples «0.6%) indicate that protein is poorly preserved, and that the nitrogen in CGS 1037A is not collagenous. In most cases, collagen sufficiently well preserved for radiocarbon dating will also be marked by atomic carbon to nitrogen ratios (C:N) of 2.9-3.6 (Ambrose, 1990). None of the six samples meet this criterion, indicating extreme depletion of nitrogen and/or heavy contamination with exogenous carbon. Discussion Similar attempts to date these remains have been undertaken before, and though not yet formally reported, are said to have yielded similar results-insufficient collagen to allow radiocarbon dating (Gillespie, 2002; Gillespie and David, 2001). This leads some to conclude that the bones are much older than the surrounding sediments, the argument being that poor collagen preservation is inconsistent with the presence of well preserved charcoal that yielded the radiocarbon dates. Inferences about re-deposition, either from sediments higher in the Cuddie Springs catchment or from deposits underlying Stratum 6b, are seen to be supported accordingly (Gillespie, 2002; Gillespie and David, 2001; Roberts et al., 2001). These inferences are unwarranted. Collagen is far more susceptible to chemical attrition than is charcoal (Taylor, 1987:53-61, 1992), especially in wet sediments. The absence of collagen in the presence of datable charcoal at this site is thus neither unusual nor an indication of any disparity in age between the megafaunal remains and surrounding, well-dated sediments. For example, of 56 unburned human remains recovered from the Willandra Lakes region and analyzed for collagen content and stable isotope values, only two contained >0.2% nitrogen (Webb, 1989:8). There is no credible suggestion that any of these remains are older than the sediments from which they were recovered, all of which are dated by other means, including radiocarbon analyses of charcoal, at less than 50 ka BP (Bowler, 1998; Bowler et al. 2003; Gillespie, 1998). Given this example (and many others like it [see especially Coltrain et al., 2004]), plus a general understanding of the factors governing collagen preservation, the absence of this material in the megafaunal samples from Cuddie Springs cannot in itself be seen to indicate age greater than that of the sediments from which they were recovered. Effective counters to arguments about redeposition, based on sedimentary criteria, have been presented elsewhere (Field and Dodson, 1999; Field et al., 2002; Furby, 1995). We