Structures that appear to be red blood cells and fibres similar to collagen have been identified in 75-million-year-old dinosaur bones from the Cretaceous, reports a paper in Nature Communications. This find suggests that the survival of organic structures in fossils may far be more common than previously thought.
Components of soft tissue, including structures that look like cells and molecules that resemble proteins, have been found before in fossils many tens of millions of years old, but only in specimens that were exceptionally well preserved and their identification proved controversial. It has long been assumed that protein molecules decay in relatively short periods of time and cannot be preserved for longer than 4 million years, therefore it is generally accepted that only parts of original proteins are preserved and that the full structure has been lost.
Sergio Bertazzo, Susannah Maidment and colleagues now report the discovery of organic structures from eight Cretaceous dinosaur bones, none of which were unusually well preserved. Some of the bones contained structures that appear to be nuclei-containing red blood cells and these exhibited a similar profile to emu blood when tested with a mass spectrometer. Other structures appeared to contain the structural protein collagen, with molecules twisted into the characteristically rope-like structure of collagen and containing fragments of the protein’s constituent amino acids. These findings suggest that even the most unassuming of fossils may be worthy of molecular analysis. The preservation of protein over geological timescales may also allow researchers to investigate the physiology and behaviour of long extinct animals.