Scientists Confirm 115-Million-Year-Old Dinosaur Blood Cells
An international team of researchers has announced the discovery of fossilized red blood cells and collagen amino acids inside a 115-million-year-old theropod dinosaur bone, a finding that challenges long-held scientific assumptions about the preservation of biological material. The discovery, published in the Proceedings of the National Academy of Sciences (PNAS) on November 2, offers a rare molecular window into the physiology of a creature that lived during the Early Cretaceous period. The structures, found in the limb bones of an Aratasaurus museunacionali, were identified using chemical and imaging techniques, providing the strongest evidence yet of red blood cells in a fossil.
What the Microstructures Reveal
The research team, led by Kliti Grice of Curtin University, examined the fossilized leg bone, which was discovered in a Brazilian mine in 2008. Inside the bone’s vascular canals—the microscopic pathways that once housed blood vessels—they found an abundance of oval-shaped microstructures. These structures, analyzed using a combination of imaging and chemical analysis, contained chemical signatures of heme, an iron-containing molecule found in haemoglobin. This marks the first time heme has been detected in situ within dinosaur fossil structures, CNN reported.
Alongside the blood cell-like structures, the team also identified traces of collagen-related molecules. These findings, ThePrint noted, provide a direct molecular link to the dinosaur’s biological makeup, moving beyond skeletal remains to offer insights into its metabolism, oxygen transport, and activity levels.
How the Blood Survived 115 Million Years
Normally, blood cells and soft tissues decompose rapidly after an animal’s death, broken down by microorganisms, oxygen, and chemical processes. Yet, in this case, the structures survived for over 100 million years. The researchers believe two key factors contributed to their preservation: the environment in which the dinosaur died and early mineralization.
The Aratasaurus museunacionali was likely buried quickly in a low-oxygen environment rich in microbial mats, conditions that slowed decomposition. CNN highlighted the Romualdo Formation in northeastern Brazil, where the fossil was found, as a region known for its exceptionally preserved fossils due to stagnant, oxygen-poor waters.
But the critical factor was mineralization. The structures were stabilized by hausmannite, a manganese oxide mineral that acted as a protective casing, preventing complete breakdown. As VICE explained, the mineral essentially functioned as “all-natural bubblewrap,” preserving the cellular framework and collagen amino acids in place. This combination of rapid burial and early mineralization created a unique set of conditions that defied the odds of preservation.
Skepticism and Scientific Debate
Despite the robust methodology, not all experts are convinced that the microscopic structures are truly red blood cells. As CNN noted, the structures differed in size and shape from red blood cells in living birds and crocodilians, raising questions about their identity. The researchers themselves acknowledged this discrepancy, emphasizing that while the chemical signatures point to heme, the structures may not be identical to modern red blood cells.
“The exciting implication is not just what we have found in this dinosaur. It is that we now have approaches that can be applied to other fossils to ask how much original biological information may still be hidden within them,” Kliti Grice said in an email to CNN.
This discovery, however, has reignited debate in the paleontological community. ThePrint reported that while similar findings have been made in the past, scientists struggled to prove the biomolecules belonged to the dinosaur and not to contaminants. In this case, the team meticulously ruled out external sources, finding no fungal filaments or microbial spores that might have infiltrated the bone after death. The presence of heme—a molecule central to blood—strengthened their case, but the scientific community remains cautious.
Implications for Paleontology and Beyond
The discovery opens new avenues for molecular-level paleontology, allowing researchers to investigate the evolution of blood, metabolism, and even activity levels in extinct animals. Grice, in a statement to ThePrint, described the finding as a “landmark discovery” that extends the known fossil record of blood and provides a direct window into dinosaur physiology.
But the implications extend beyond paleontology. CNN questioned whether this type of preservation applies to other fossils, and VICE suggested that other similar specimens might be in museum collections worldwide or among the next bones researchers excavate. If researchers find similar evidence in more specimens, it could lead to a paradigm shift in how we study ancient life, potentially unlocking a wealth of biological information previously thought lost to time.
For now, the focus remains on the Aratasaurus museunacionali. The researchers plan to apply their analytical techniques to other fossils, hoping to uncover more hidden biological secrets. As Grice noted, the real excitement lies not in recreating dinosaurs à la Jurassic Park, but in using this discovery to better understand the world they lived in.
