Limb bones from a 115-million-year-old meat-eating dinosaur in northeastern Brazil contain mineralized red blood cells, and inside those cells researchers have now detected heme, the iron-bearing molecule that carries oxygen in hemoglobin. Curtin University in Western Australia led the study, which appeared in the Proceedings of the National Academy of Sciences in early November. Its authors call it the first definitive chemical confirmation of hemoglobin-derived molecules in fossilized dinosaur blood cells.
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Professor Kliti Grice, who directs Curtin’s WA-Organic and Isotope Geochemistry Centre and led the team, called the result “a landmark discovery.” Her research was supported by a 2021 Australian Research Council Laureate Fellowship, and co-authors came from the Japan Agency for Marine-Earth Science and Technology, the Brazilian National Museum, the Regional University of Cariri and Johns Hopkins University.
Aratasaurus museunacionali and the Romualdo Formation bones
The animal is Aratasaurus museunacionali, a theropod found in northeastern Brazil and described from fossils discovered in 2008. Sci.News places the hind-limb bones at the Mina Pedra Branca site in the Romualdo Formation. Popular Science described the individual as a juvenile more than 10 feet long, though the animal likely grew larger. Thin slices of the bone revealed small ellipsoidal structures in the vascular canals, the passages that once held blood vessels.
Those structures measure roughly 23 by 20 micrometers, and the team interprets them as mineralized remnants of red blood cells.
Heme B, a derivative and the limits of the claim
Scanning electron microscopy found the structures, and further imaging and spectroscopic analyses located heme-related chemical signatures in them, according to the ScienceDaily version of the Curtin release. Sci.News reports the molecules identified were heme B and a chemically altered derivative, 3,8-diethyl heme B. The team also found amino acids associated with collagen. Grice said that detecting intact heme-derived molecules in 115-million-year-old red blood cells is astonishing.
The claim is narrower than some coverage implies. The study does not argue that intact blood or hemoglobin proteins survived, only that molecules derived from hemoglobin did. Popular Science noted that no outside scientist is quoted in its report, so the first-ever framing rests on the authors and their institution. Earlier studies had reported blood-cell-like structures in fossils without confirming these molecules.
Hausmannite, rapid burial and the astrobiology angle
Preservation is the puzzle. The team links survival to hausmannite, a manganese oxide mineral that it says helped stabilize the cells and their molecular contents, and suspects the animal was buried quickly in a low-oxygen setting rich in microbes. Grice said the findings challenge longstanding assumptions that certain biomolecules, hemoglobin among them, cannot survive deep time, in the Curtin media release.
The author list is long. Beyond Grice, named collaborators include Yuta Isaji, Jasmina Wiemann, Paul F. Greenwood, Madison Tripp, Maria A. Diaz Mateus, Stephen F. Poropat, Xiao Sun, Pieter T. Visscher, Naohiko Ohkouchi, Juliana M. Sayao, Antonio A. F. Saraiva and Alexander W. A. Kellner, with about 20 more authors in the full paper. The work appears in volume 123, issue 46 of the journal, and the Curtin team supplied the geochemistry while Brazilian co-authors supplied the fossil and its collection history.
If the chemistry holds up, the practical payoff is a new route into physiology. Hemoglobin chemistry could help paleontologists reason about oxygen handling and metabolism in extinct animals, questions that bone shape alone cannot answer, and the same preservation recipe of manganese minerals plus fast burial could guide where researchers sample next. Curtin’s release stresses that other fossils may carry molecular information that conventional methods have missed.
Context matters for a claim like this one. Claims of soft-tissue or blood remnants in fossils have drawn arguments for years, mostly over contamination and whether the original molecules could really last. The Curtin team answers that worry with the location of the cells deep inside vascular canals and with the identification of a chemically altered heme derivative, which points to degradation products of ancient blood rather than modern contamination. Independent replication, and an outside assessment of the spectroscopy, will determine how widely the result is accepted.
Sampling is another open item. The release and its coverage describe limb bones of one animal, and a single individual cannot show whether hausmannite-rich burial settings across the Romualdo Formation, or in other Early Cretaceous deposits, routinely trap heme in the same way.
Professor Martin Van Kranendonk, head of Curtin’s School of Earth and Planetary Sciences, said the research redefines how molecular structures can be preserved over long time frames and pointed to astrobiology: if molecules can persist for more than 100 million years under the right conditions, the search for ancient biosignatures on Earth and beyond may need to look in different places. Grice frames the work as the start of what she calls molecular-level paleontology, with possible insight into blood evolution, metabolism and activity levels in extinct animals.
The full paper, titled for heme signatures in mineralized red blood cells within vascular canals of a dinosaur bone, is listed under DOI 10.1073/pnas.2614248123, with the EurekAlert posting carrying the same findings. Neither the Curtin release nor the coverage reviewed gives the number of specimens sampled, and a second laboratory repeating the chemistry is the evidence that would settle how far the result extends to other fossils.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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