Tests on 115m-year-old dinosaur bone reveal heme, scientists say
Chemical tests on an Aratasaurus hind-leg bone from north-east Brazil identified heme, which researchers interpret as evidence of fossilised red blood cells.
The story in focus
Researchers say electron microscope images of a 115m-year-old Aratasaurus hind-leg bone from north-east Brazil show round structures resembling red blood cells, and chemical tests identified heme, the compound that lets haemoglobin carry oxygen. The claim, published in PNAS, is disputed by another palaeontologist.
- The Aratasaurus fossil was found in a mine in 2008 and is held at the National Museum of Brazil.
- Electron microscope images showed small round structures in channels where blood vessels once ran.
- Chemical tests identified heme and its breakdown products, plus amino acid building blocks for collagen.
- Prof Mary Schweitzer disputes the red blood cell identification, citing the structures' concave shape.
- Lead researcher Prof Kliti Grice said the work does not imply proteins or DNA survive in ancient fossils.
What the tests found
Chemical tests on the hind-leg bone of an Aratasaurus, a small meat-eating dinosaur that lived in what is now north-eastern Brazil about 115m years ago, identified heme, the organic compound that allows haemoglobin to carry oxygen around the body, according to The Guardian.
Electron microscope images revealed small, round structures resembling red blood cells in fine channels where blood vessels once ran. Tests also found traces of the amino acid building blocks for collagen, a key protein in connective tissue. The study appears in Proceedings of the National Academy of Sciences.
Why the claim is contested
Prof Kliti Grice of Curtin University, who led the team, said fossilised red blood cells with distinct chemistry related to heme had never been found in situ in any fossil. She suggested a manganese compound called hausmannite, which formed in and around the cells, may have stabilised them before fossilisation.
Prof Mary Schweitzer of North Carolina State University is not convinced. She said the dinosaur's red blood cells should show a nuclear bulge, making them appear dome-like on both sides, whereas the structures Grice found are concave. Schweitzer was more persuaded by the heme and collagen amino acid findings.
Caveats and implications
Biological tissues and molecules can break down quickly, leaving little trace in ancient fossils. Grice urged extreme caution, saying the work does not imply that large molecules such as proteins or DNA survive in ancient fossils, and that her aim was not to find Jurassic Park DNA.
She said the results suggest extraordinary molecular information may already sit in museum collections, waiting for new questions to be asked of old fossils.
What did chemical tests on the Aratasaurus bone identify?
Tests identified heme, the compound that lets haemoglobin carry oxygen, and its breakdown products, plus amino acid building blocks for collagen, The Guardian reported. Researchers interpret accompanying round structures as fossilised red blood cells.
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