The difference between the uncalibrated radiocarbon age of the Manis mastodon and its calibrated calendar age — the true number of years before the present — is meaningful: a sample that reads as approximately 12,000 radiocarbon years before present might calibrate to approximately 13,800 to 14,000 calendar years before present, depending on which calibration curve is used and what the specific measurement uncertainty is.

When the Waters team published their results in 2011 in the journal Science, the calibrated age of the mastodon was established at approximately 13,800 years before the present — with the range of dates from different samples and different calibration approaches clustering around this figure.

Some analyses produced results slightly younger, some slightly older, but the overall picture was consistent: this mastodon died roughly 13,800 to 13,900 calibrated years ago.

The Clovis horizon, using the currently accepted dates, falls at approximately 13,000 to 13,200 calibrated years before the present.