Reports of proteins in fossilized bones have been a subject of controversy in the scientific literature because it is assumed that fossilization results in the destruction of all organic components.

In this paper, a novel combination of analytical techniques is used to address this question for an exceptionally well-preserved Edmontosaurus sacrum excavated from the Upper Cretaceous strata of the South Dakota Hell Creek Formation.

Cross-polarized light microscopy (XPol) shows birefringence consistent with collagen presence.

Tandem LC-MS unambiguously identified, and for the first time quantified, hydroxyproline, a unique collagen-indicator amino acid, in acid-digested samples from the Edmontosaurus.

LC-MS/MS bottom-up proteomics shows identical collagen peptide sequences previously identified and reported for another hadrosaur and a T. rex sample.

Detection of soft tissues (e.g., proteins) in fossil bones is a growing field of study and this paper contributes to the list of such findings. Corroborating results from a novel combination of three independent analytical techniques are presented which taken together provide experimental evidence for the conclusion that collagenous protein remnants in some dinosaur bones are original (endogenous) to the fossils and thus providing further evidence addressing this long-standing controversy in the scientific literature.