A fossil of Aratasaurus museunacionali, a theropod that lived around 115 million years ago in what is now northeastern Brazil, may preserve structures resembling red blood cells. Researchers examined fragments from one of the dinosaur’s leg bones and also detected heme, an organic compound associated with hemoglobin, which carries oxygen in blood.
The study was led by scientists at Curtin University in Australia and published in the Proceedings of the National Academy of Sciences. The fossil was found at a Brazilian mine in 2008 and is held by the National Museum. The researchers say this is the first reported case of cell-like structures in a fossil accompanied by chemical evidence related to heme.
Microscopic analysis revealed small, rounded structures inside channels where blood vessels had passed. Chemical tests also detected products from the breakdown of heme and components associated with collagen. The researchers say that combining the visual observations with chemical evidence is important, since a cell-like appearance alone cannot establish that a structure is biological in origin.
The team suggests that hausmannite, a manganese mineral found in the material, may have helped stabilize or reproduce the structures during fossilization. Rapid burial in an environment with microbial activity and limited oxygen may also have contributed to their preservation. The researchers do not claim that intact blood cells survived for 115 million years; rather, they interpret the findings as a mineralized record of structures and chemical components linked to the animal’s biology.
The interpretation is not settled. Paleontologist Mary Schweitzer of North Carolina State University told The Guardian that the structures’ concave shape differs from the expected appearance of dinosaur red blood cells, which she said should bulge on both sides. She viewed the chemical evidence for heme and collagen-related components as more persuasive. Study leader Kliti Grice has also cautioned that the findings do not mean large, complex molecules such as proteins or DNA have survived intact.
If further research confirms the results, the evidence could help scientists investigate aspects of dinosaur physiology, including blood evolution, metabolism and activity levels. Grice also noted that museum collections may contain microscopic, chemical and mineral clues that earlier analyses missed. The study’s aim, she said, is not to find dinosaur DNA for recreating extinct animals, but to understand how much molecular information can persist over millions of years.
Sources: Olhar Digital.