Dinosaur bone yields heme traces, but fossil blood-cell claim faces scrutiny

Scientists examining hind leg bones from Aratasaurus, a small meat-eating dinosaur that lived in what is now north-eastern Brazil 115 million years ago, say they have identified fossilised red blood cells. Electron microscopy revealed rounded structures inside former blood-vessel channels, while chemical tests detected heme, a component of haemoglobin, and its breakdown products. The study appears in Proceedings of the National Academy of Sciences.

Research leader Kliti Grice of Curtin University suggests a manganese mineral may have helped preserve the material. But palaeontologist Mary Schweitzer questions the cell identification: the concave structures lack the bulging shape she expects. She considers the reported heme and collagen amino-acid findings more convincing.

The dispute concerns how much biological information ancient fossils can retain, given that tissues and molecules can degrade rapidly. Grice says museum collections could hold further molecular evidence, but cautions that this research does not demonstrate the survival of large biological molecules such as proteins or DNA in ancient fossils.