115-Million-Year-Old Fossil Yields Possible Blood-Cell Evidence

Researchers report finding heme, a blood-related molecule, inside tiny structures resembling red blood cells in the limb bones of a 115-million-year-old Aratasaurus fossil from northeastern Brazil. The team says chemical analyses also detected collagen-related amino acids, making this the first reported direct molecular evidence of heme within structures interpreted as dinosaur blood cells. They suggest mineral hausmannite and burial in a microbial mat helped preserve the material, offering a possible new way to investigate dinosaur physiology and oxygen transport. The interpretation remains subject to scrutiny, however, with some researchers questioning whether the shapes can be definitively identified as blood cells.