Scientists studying a dinosaur limb bone from Brazil report tiny ellipsoid structures and chemical traces of heme, but some experts remain unconvinced.
By Hermes-Vector AI Desk
Researchers studying a fossilized dinosaur limb bone report tiny ellipsoid structures about 20 micrometers in diameter that may be fossilized red blood cells, along with preserved heme, the oxygen-carrying component of hemoglobin.
The bone came from a fossil-rich site in northeastern Brazil called Mina Pedra Branca and belonged to the dinosaur Aratasaurus museunacionali. The specimen dates to the Cretaceous Period and is 115 million years old.
The team prepared thin cross-sectional slices of bone and used focused electron beams to image the limb bone’s internal structure. That revealed ellipse-shaped microstructures within the fossilized network of blood vessels.
A map of the ellipsoids’ chemical element composition showed they were full of iron, carbon and nitrogen, all components of heme. Additional analyses suggested the presence of porphyrins, ringlike organic compounds found in blood and precursors of heme. The researchers also separated and identified the molecular contents of a bone extract to rule out contamination from other porphyrins, such as the pigment chlorophyll.
The team’s analyses found a manganese oxide mineral called hausmannite within the ellipsoid structures. The researchers propose that hausmannite may have acted as a time capsule, preserving the cellular structures and protecting the molecules within, including collagen amino acids.
Mary Schweitzer, a paleontologist at North Carolina State University who was not involved in the new study, says she does not think the findings fully meet established criteria for identifying fossilized blood cells.
The heme biomarkers, for example, do not appear to be localized to the round structures alone, as would be expected in fossilized blood cells, but come from analysis of the entire bone, Schweitzer says. The proposed red blood cells also differ in size and shape compared with red blood cells from living birds and reptiles, she says.
"I am not convinced" that the research team has definitively identified heme compounds, Schweitzer says. "I do applaud them for bringing a plethora of methods to the study. Extraordinary claims require extraordinary evidence, and that does require state-of-the-art technology."
Kliti Grice of Curtin University in Bentley, Australia, says her team’s interpretation rests on the convergence of anatomy, morphology, mineralogy, elemental analysis and molecular chemistry. She says no one really knows what a dinosaur’s red blood cell shape would be, or how fossilization might distort the original shape of the structures.
The ability to identify such structures could offer a molecular window into the physiology of long-extinct animals, including their metabolism and activity levels, Grice says. The researchers plan to expand their work to other fossils from different species, geological time periods and environments to better understand how widespread this type of preservation might be.
Sources
This article was drafted with AI assistance and checked against the sources above. Company claims are reported as claims. Cover image is AI-generated.
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Scientists led by Curtin University report heme molecules inside mineralized cell-like structures in a Brazilian dinosaur fossil, the first direct chemical confirmation of blood-derived compounds in fossilized red blood cells.
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