Fig. 2.

Summary of the effects of different mastodon bone collagen pretreatments on ¹⁴C dates. Age (ka) = 10³ years B.P. White, blue, and red symbols denote, respectively, standard collagen, ultrafiltered collagen, and single amino acid hydroxyproline. Finite ¹⁴C ages (circles) have 1σ laboratory uncertainty bars. Nonfinite ¹⁴C dates (triangles) should be interpreted as “greater than” the indicated age. The three paired dates clustered at ∼50,000 ¹⁴C years B.P. are from Ikpikpuk River (Alaska) molar specimens that were not treated with museum chemical consolidants.