Somewhere, Dr John Hammond is reaching for his cane. A team led by Kliti Grice of Curtin University in Western Australia says it has found chemical traces of red blood cells in the bones of a dinosaur that died about 115 million years ago. The paper, in Proceedings of the National Academy of Sciences (PNAS) on 2 November, reports heme signatures in what the authors describe as mineralised red blood cells, sitting in the vascular canals of the bone where the blood vessels once ran. Heme is the iron-carrying part of haemoglobin, the stuff that makes blood red and gives a rare steak its moral complexity.
The dinosaur in question is Aratasaurus museunacionali, a theropod about three metres long from the Early Cretaceous of north-east Brazil. It is not a household name. It is known from a partial leg, found in a slab of grey rock, and it was named in 2020 in honour of Brazil’s Museu Nacional in Rio de Janeiro, which had burned down in 2018. “Arata” is usually translated from Tupi as “born from fire”. Now, apparently, it may have been born with blood in it, which is more than you can say for most fossils.
Before anybody books a helicopter to an island off Costa Rica, there is a dissenting voice, and it belongs to the person best placed to have one. Mary Schweitzer of North Carolina State University, who caused a sensation in 2005 when she reported soft tissue inside a Tyrannosaurus rex bone, told Live Science: “I am not convinced that the images they figure are remnant RBCs.” She points out that the structures are smaller than most non-mammalian red blood cells and lack the bulge you would expect from a nucleus. Dinosaur blood cells, like those of birds and crocodiles, should have one. She was generous about the work all the same, telling Live Science, “I very much appreciate this team bringing rigor to the study of deep time fossils.” Palaeontology is one of the few fields where people can disagree that politely about blood.
So what we have is a chemical signature that fits blood and some tiny round shapes that may or may not be the cells themselves. That is a long way from the Jurassic Park recipe, which needed a mosquito, a lump of amber and some frog DNA to fill the gaps. Heme is not DNA. Nobody is cloning anything from this, and Jeff Goldblum can stay in his chair. What it might do, if it holds up, is tell palaeontologists that the inside of a fossil bone can hold on to much more of the original animal than anyone assumed a generation ago, which is the slow, unglamorous revolution Schweitzer started twenty years ago.
Michael Crichton published Jurassic Park in 1990, when the idea of getting anything biological out of a dinosaur was a novelist’s daydream. Thirty-six years later, the scientists are arguing over whether the red bits are cells or just red bits. That is progress, and it is also the best possible argument for not opening the theme park just yet.
Sources: Live Science; Grice, K. et al. (2026), “Heme signatures in mineralized red blood cells within vascular canals of a 115-million-year-old dinosaur bone”, PNAS 123, e2614248123.
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