Traditionally, there was little hope that biomolecules might be recovered from bone more than a few thousand years old. However, 20 years ago, partial amino acid sequences were identified from the shells of mollusks ≈80 million years old (33). Gurley et al. (34) followed with a report of amino acids in the bony tissues of the Late Jurassic (≈150 million years ago) sauropod dinosaur, Seismosaurus, and more recently the small and highly acidic bone protein, osteocalcin, has been recognized immunologically in extracts of dinosaurian bone (35). Stable isotope studies (36), including those done on the specimen used in the following study (37), indicate that at least some of these molecules are endogenous to the fossils, rather than arising from younger exogenous contaminants. These results suggest that significant protein remnants may exist in fossil bone.