Ancient blood traces found in 115-million-year-old Brazilian dinosaur fossil

A new study claims to have found the oldest chemical evidence of blood-related material in a dinosaur fossil, with red blood cell-like structures and heme signatures discovered in a 115 million-year-old Brazilian specimen. The findings were published Monday in the journal PNAS. The research examined limb bones of the small theropod Aratasaurus museunacionali, using microscopic and chemical analysis to identify structures within vascular canals. The team detected heme-related compounds and suggests rapid burial in a low-oxygen environment with microbial mats helped preserve the material, including mineralized structures and collagen-associated amino acids. Some experts dispute the conclusion, noting the structures lack the nuclear bulge typical of non-mammalian red blood cells and appear smaller than expected. Skeptics acknowledge the value of the molecular approach but argue morphological similarity is not met.