Brazil dinosaur fossil discovery reveals preserved red blood cells

An international research team has identified fossilized red blood cells within the right leg bone of an Aratasaurus museunacionali, a carnivorous dinosaur that lived in Brazil approximately 115 million years ago.

The study, published in the journal Proceedings of the National Academy of Sciences (PNAS), chemically detected molecules derived from hemoglobin. Researchers found preserved heme, the component responsible for oxygen transport, within the specimen. This discovery provides some of the strongest evidence to date of blood cell presence in dinosaur fossils.

The Aratasaurus museunacionali is a theropod species that measured up to three meters in length and weighed about 34 kilograms. The fossils were recovered from the Romualdo Formation in the Araripe Basin, located in Northeast Brazil.

Scientists attribute this rare preservation to rapid burial in an oxygen-poor environment rich in microorganisms. The red blood cells were mineralized by hausmannite, a manganese oxide that acted as a natural capsule to stabilize cellular structures and biomolecules over geological timescales. This finding challenges existing theories regarding the survival limits of biomolecules like hemoglobin and may offer new insights into the evolution of metabolism and astrobiology.