Researchers have identified mineralized red blood cells and heme molecules in the limb bone of an Aratasaurus museunacionali fossil from Brazil.
An international research team led by scientists at Curtin University has identified what appear to be fossilized red blood cells and blood-derived molecules inside a 115-million-year-old dinosaur leg bone.
The fossil belongs to an Aratasaurus museunacionali, a small theropod dinosaur that lived approximately 115 million years ago. The specimen was recovered from a mine in Brazil in 2008 and is held at the National Museum of Brazil.
Upon examining the bone's vascular canals, researchers detected ellipsoidal microstructures. According to the study published in the journal Proceedings of the National Academy of Sciences, these structures average approximately 23 micrometers in length and 20 micrometers in width.
To determine if the structures were biological in origin rather than contamination, the team used high-performance liquid chromatography–mass spectrometry. This analysis revealed that the bone extract was dominated by heme B, a molecule that helps blood cells carry oxygen. The researchers also detected traces of hydroxyproline, an amino acid associated with collagen.
To rule out contamination from the surrounding environment, the team compared the bone's chemistry to the surrounding rock. While the surrounding rock contained signatures of photosynthetic microbes, such as chlorophyll and bacteriochlorophyll, the heme B was found specifically within the bone extract.
The researchers suggest the exceptional preservation may be due to the geological setting: a microbial mat in shallow, low-oxygen waters. They propose that manganese oxide mineralization, specifically a mineral called hausmannite, may have helped stabilize or replicate the delicate cellular structures during fossilization.
While the findings are described by lead author Kliti Grice as a "landmark discovery," the results have drawn scrutiny.
Prof. Mary Schweitzer of North Carolina State University noted that the structures found were concave, whereas dinosaur red blood cells should have a "nuclear bulge" making them appear dome-like on both sides.
Additionally, some researchers have noted that the purported cells appear rounder and wider than those of living birds and crocodilians. The research team acknowledged that while they found no evidence of fungi or microbes, they cannot completely rule out the possibility of heme-producing microbes.
If confirmed, this discovery could allow scientists to investigate the evolution of blood, metabolism, and activity levels in extinct animals. It also suggests that significant molecular information may exist in museum collections that has not yet been analyzed using modern techniques.
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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