Scientists report fossilised red blood cells in 115-million-year-old dinosaur bone - Space and astronomy

Microscopic structures and chemical traces of heme in an Aratasaurus fossil from Brazil may preserve evidence of the dinosaur’s original blood, although researchers say the interpretation remains disputed.

Researchers say they have found structures resembling fossilised red blood cells in the hind leg bones of an Aratasaurus, a small meat-eating dinosaur that lived in what is now north-eastern Brazil about 115 million years ago.

Electron microscope images showed small, round structures inside fine channels where blood vessels once ran. Chemical analysis also detected heme, the organic compound that enables haemoglobin to carry oxygen, along with breakdown products of the molecule.

The fossil remains were discovered in a mine in 2008 and are held at Brazil’s National Museum. Prof Kliti Grice of Curtin University in Western Australia, who led the research, said the findings represent a mineral and molecular trace of the animal’s original biology. The study has been published in Proceedings of the National Academy of Sciences.

The team’s interpretation was supported by the detection of heme and traces of amino acids that form collagen, a key structural protein. The researchers suggest that hausmannite, a manganese compound that formed around the structures, may have helped stabilise them before fossilisation and contributed to the preservation of the amino acids.

The findings remain controversial. Prof Mary Schweitzer of North Carolina State University, who has studied possible blood vessels and soft tissues in dinosaur fossils, said she was not convinced that the structures were red blood cells. She noted that dinosaur red blood cells should have a nuclear bulge and appear dome-shaped on both sides, whereas the structures in this fossil are concave.

Schweitzer was more persuaded by the evidence for heme and collagen-related amino acids. The research challenges the assumption that organic material cannot survive in fossils for more than a million years, while also highlighting the need for strong analytical evidence.

Grice stressed that the discovery does not suggest that large molecules such as proteins or DNA survive intact in ancient fossils. Instead, she said, the work may help scientists determine how much molecular information can remain preserved over deep time and encourage further analysis of fossil specimens in museum collections.

Sources: The Guardian Science.