Red blood cells and 'heme' found for the first time in a 115-million-year-old dinosaur fossil

An international research team led by scientists at Australia's Curtin University has presented evidence of intact red blood cells and heme, a core component of blood, found for the first time inside a dinosaur fossil about 115 million years old.

The researchers were studying a hind-leg bone of a theropod dinosaur called Aratasaurus museunacionali. The dinosaur lived about 115 million years ago in what is now Brazil.

While examining the internal structure of the bone, the scientists saw round microscopic structures under the microscope that looked like red blood cells. They did not rely on appearance alone to reach their conclusion.

Using a technique called high-performance liquid chromatography-mass spectrometry (HPLC-MS), they confirmed that the round structures contained a molecule called heme. Heme is the component that carries oxygen in blood and is the core part of the hemoglobin protein in red blood cells.

The scientists also tested whether material from outside bacteria or plants could have mixed in. They found that the heme inside the bone had not mixed with any plant or bacterial material from outside.

Further analysis with Raman spectroscopy and electron microscopy showed that the red blood cells had become trapped and mineralised inside a natural manganese oxide mineral called hausmannite (Mn3O4). According to the researchers, that mineral coating protected the blood molecules from being destroyed over millions of years.

Professor Cletty Grice, one of the research team's leads, described the discovery as thrilling. She said that, as a geochemist, when she found the blood components she realised they were about to reach a major milestone in the history of science.

In Professor Grice's view, a fossil is not only lifeless stone; in special environments a fossil can also retain its original animal's molecular and chemical information. That could make it possible to answer questions that paleontology alone cannot solve.

She has called on museums around the world to re-examine, with modern technology, the thousands of fossils kept in their display cases.