Doneraile’s Reindeer Cutmark
The numerical label 31,913 BCE is a modern conversion, not an exact prehistoric calendar date. For periods this old, scholars normally use calibrated years before present (cal BP, with “present” conventionally fixed at 1950) or broad geological stages. The calibration curve itself becomes less exact further back in time, while the survival of enough original collagen for radiocarbon dating is a separate challenge. Modern re-dating of Irish cave bones has shown why such caution matters: improved pretreatment has made several Castlepook dates thousands of radiocarbon years older than earlier results.