Discovery and chemical evidence
Researchers working on the hind limb of an Aratasaurus, a small meat-eating dinosaur from north-eastern Brazil, report finding microscopic structures that they interpret as fossilised red blood cells. Chemical tests on the bone material also detected the presence of heme, the organic compound associated with haemoglobin that transports oxygen in blood.
Rare preservation of soft biology
Preservation of cellular and molecular remnants in deep-time fossils is uncommon, and claims of retained blood-related compounds attract particular interest because they speak to how organic molecules can survive over geological timescales. The team’s findings add to a small but growing set of reports suggesting that under certain conditions even labile biomolecules may be detectable in Mesozoic bones.
Interpretation and caution
The researchers present microscopy and chemical analysis as evidence for their interpretation, but such results typically invite further scrutiny. Independent replication, additional testing to exclude modern contamination, and detailed taphonomic analysis are necessary to establish definitively whether the structures and compounds are original to the dinosaur tissue or the result of later processes.
Implications and next steps
If confirmed, the presence of preserved blood-cell structures and heme could offer new avenues for studying dinosaur physiology and the processes that enable molecular preservation. The report is likely to prompt additional sampling of the specimen, wider comparative analyses of other fossils from the region, and peer review to assess the robustness and broader significance of the findings.