In ancient samples, where DNA degradation often prevents successful sequencing, proteins can survive for much longer — their molecular structure is more stable than the double helix of DNA, and they can persist in mineralized bone for tens of thousands of years under favorable conditions.

Protein mass spectrometry — a technique that identifies proteins by their mass and charge characteristics, breaking proteins into their component peptide fragments and reading those fragments against reference databases — can identify the species from which a protein derived and, in some cases, provide information about the specific tissue type.

The protein analysis applied to the embedded fragments produced a clear result: the fragments were mastodon bone.

Not from some other animal, not from an unrelated species, but from a mastodon — Mammut americanum.