Scientists Find Potential Red Blood Cells In Dinosaur Bone

Evidence Of Prehistoric Blood Cells

Researchers studying a 115-million-year-old dinosaur bone have reported finding some of the strongest evidence to date of preserved red blood cells. The study, published in the Proceedings of the National Academy of Sciences, focuses on a partial hind limb of Aratasaurus museunacionali, a theropod dinosaur from the Early Cretaceous period. This specimen was recovered in 2008 from the geological site Mina Pedra Branca in northeastern Brazil, located within the Romualdo Formation, a rocky area known for its exceptionally preserved fossils.

Soft biological samples, including tissues and cells, rarely survive the fossilization process, making such discoveries highly controversial. While previous studies since the late 1990s have claimed to find red blood cell-like structures in reptile fossils, these findings have been subject to intense debate. The current research employs a combination of advanced microscopic imaging and chemical analyses to provide a more comprehensive argument for the existence of these cells, bringing together evidence regarding location, appearance, mineral composition, and chemical signals.

Chemical And Structural Analysis

Within the vascular canals of the bone—microscopic tubes that normally house blood vessels and nerve fibers—the team identified numerous oval-shaped microstructures. To verify these findings, the researchers looked for chemical signatures consistent with red blood cells. They successfully detected heme, a molecule found in hemoglobin, which is the protein responsible for carrying oxygen in red blood cells. According to the authors, this marks the first time heme has been detected in situ, or within the structures themselves, in a dinosaur fossil.

Lead author Kliti Grice, an organic geochemist and professor at Curtin University, suggests that the specific burial conditions at the Brazilian site played a critical role. The researchers believe that stagnant waters limited oxygen levels, which slowed the decomposition of the remains. Additionally, the presence of manganese oxides, specifically hausmannite, may have helped stabilize and preserve the cellular structures over millions of years. Grice noted that while bones provide information about anatomy and evolution, cellular preservation gives access to the chemistry of the living animal.

Scientific Debate And Implications

Despite the evidence, the discovery remains a point of contention among experts. Some scientists argue that the structures do not meet established standards for identifying fossilized blood cells. Critics have noted that the size and shape of the discovered cells differ from those found in modern birds and crocodilians. Furthermore, some question the significance of the manganese oxides, as they are not found in living red blood cells. Grice responded that these minerals likely formed during the fossilization process rather than being original components of the cells.

Timothy Cleland, a physical scientist at the Smithsonian Institution’s Museum Conservation Institute, noted that while the study opens new avenues for exploring heme preservation, it does not necessarily bring science closer to recovering dinosaur DNA, as seen in popular fiction. He explained that heme and DNA are different molecules that fossilize in bone in different ways, meaning the survival of one does not guarantee the survival of the other. He questioned whether this kind of preservation extends beyond this single dinosaur to other species within the Romualdo Formation.

Future Research Directions

If these findings are validated across more specimens, it could allow scientists to ask more sophisticated questions about the physiology of extinct animals. Researchers could potentially investigate how dinosaurs transported oxygen and how their internal tissues functioned compared to modern animals. Grice and her team plan to expand their research to other fossils from various species and geological periods to determine how widespread this type of preservation is, noting that many museum collections worldwide may contain hidden molecular information.

Mary Schweitzer, a professor emeritus at North Carolina State University, acknowledged that the use of multiple analytical techniques is an exciting advancement. She suggested that exploring the interaction between burial environments and degrading organisms could reveal new information about prehistoric diseases and biological evolution. By moving beyond the idea that such preservation is impossible, she believes scientists can learn more about how molecules have evolved over time.