Scientists have discovered traces of dinosaur blood dating back 115 million years

In the bones of a dinosaur that lived about 115 million years ago in what is now Brazil, researchers have found mineralized structures similar to red blood cells and chemical traces of heme, a component of hemoglobin. The discovery can help scientists study not only the skeletons of ancient animals, but also the features of their body. At the same time, experts are still arguing about whether the detected formations are really blood cells. The information about what was found inside the fossilized bones and why the discovery sparked discussion is in the Izvestia article.

Traces of blood inside the fossil

An international team of researchers has discovered signs of ancient blood in the bones of the hindlimb of Aratasaurus (Aratasaurus museunacionali), a predatory dinosaur that lived in the Early Cretaceous period. His remains were found in 2008 in a gypsum quarry in northeastern Brazil. The age of the fossil is estimated at about 115 million years.

Scientists have studied thin sections of bones and found numerous microscopic ellipsoid formations inside the channels through which blood vessels passed during life. In size, location, and appearance, they resembled red blood cells. Chemical analysis also revealed heme, an iron—containing component of hemoglobin, which is involved in oxygen transport.

The work was published in the journal Proceedings of the National Academy of Sciences (PNAS). The authors believe that the combination of microscopic structures, their location inside bone channels, and chemical traces of heme provides the most convincing evidence to date of the preservation of blood components in the dinosaur fossil.

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What is preserved in the bones

The researchers used several methods of microscopic and chemical analysis to study not only the shape of the formations found, but also their composition. In particular, they found compounds related to heme, as well as amino acids characteristic of collagen— a protein that forms the basis of bone tissue.

Heme is a part of hemoglobin, a protein of red blood cells that helps the blood carry oxygen. However, the scientists did not find whole hemoglobin or intact cells. We are talking about mineralized structures and chemical residues that could have been preserved from the original tissues.

According to her, the results cast doubt on the notion that some biomolecules are unable to persist for such a long time. However, the study did not reveal ancient DNA. The presence of traces of heme and collagen amino acids does not mean that the fossil contains the genetic material or whole proteins of a dinosaur.

The mineral worked like a time capsule

The authors of the study suggest that the preservation of microscopic structures was helped by the conditions in which the dinosaur remains found themselves after death. According to their version, the animal was quickly buried in a low-oxygen environment rich in microorganisms. Such conditions could slow down the destruction of tissues and promote their mineralization.

Inside the bones, the researchers found gausmanite, a mineral that is an oxide of manganese. It could stabilize cell-like structures and their associated molecular components, including traces of heme and the amino acids collagen. According to scientists, mineralization has helped preserve their shape and chemical characteristics even after millions of years.

The researchers believe that such methods can help obtain additional information from fossils that are already in museum collections.

Why are scientists arguing about the find?

Despite the chemical evidence, the interpretation of microscopic formations as red blood cells raises questions from some experts. A paleontologist from North Carolina State University, Mary Schweitzer, who was not involved in the work, questioned whether their shape corresponded to the structure of dinosaur red blood cells. She noticed that some formations are about 15 microns in size.

Although the similarity in shape alone is not enough to definitively confirm their origin, Schweitzer did not reject the chemical results of the work. She noted that the authors used several methods to confirm the presence of heme and collagen in the bone tissue. Other experts also urge to distinguish between the detection of chemical traces of ancient biology and the proof that researchers are looking at preserved blood cells.

Thus, the discovery does not yet mean that scientists have found intact dinosaur blood. It shows that fossils may contain molecular traces that allow us to study ancient organisms on a deeper level. Further research will help to establish how widespread such a conservation mechanism is and what other information about the physiology of extinct animals can be extracted from fossils.