Dating of Rattus exulans and bird bone from Pleasant River (Otago, New Zealand):: radiocarbon anomalies from diet

Radiocarbon ages of Rattus exulans bone recovered from the Pleasant River, Otago, archaeological site were originally rejected on the basis of C-14 variability allegedly caused by laboratory processing. Subsequent work revealed no burial contaminant that could have affected the results on bone protein as processed. We present the analysis of bone from seven bird species at the Pleasant River site, which showed that marshland fowl also had up to 300 yr radiocarbon variation in their ages, but maintained terrestrial-range delta(13)C and delta(15)N values. The apparent dietary effect that offsets marshland fowl 14C ages at Pleasant River suggested there was a similar, diet-based cause for the anomalous radiocarbon ages for some R. exulans at the site, rather than a laboratory contamination or processing effect.