Intact red blood cells and heme molecules discovered in 115-million-year-old dinosaur fossil

Paleontologists confirm first chemical evidence of intact red blood cells in dinosaur fossils

CANBERRA / LONDON — Paleontologists have confirmed the first chemical evidence of intact red blood cells and heme biomolecules within 115-million-year-old dinosaur fossils, a discovery that challenges longstanding assumptions that such proteins cannot survive deep time.

The findings, published in the Proceedings of the National Academy of Sciences, involve fossils of Aratasaurus museunacionali, a juvenile theropod dinosaur from the Early Cretaceous period discovered in 2008 in present-day northeastern Brazil. After examining thin slices of the fossilized limb bones, researchers located mineralized red blood cell components and a complex manganese oxide called hausmannite.

The study's authors determined that the exceptional preservation resulted from rapid burial in an environment rich in microbes but low in oxygen shortly after the dinosaur's death. The hausmannite mineral helped maintain the cellular structures of heme, a ring-shaped molecule containing iron that binds hemoglobin and other proteins.

"This really is a landmark discovery," said Kliti Grice, a study co-author and chemist at Curtin University in Australia. "These findings challenge longstanding assumptions that certain biomolecules such as hemoglobin cannot survive deep time."

While previous studies have reported possible red blood cell structures in fossils, this research is the first to chemically prove the presence of hemoglobin-derived molecules inside such cells. The team ruled out contamination by analyzing surrounding rock, which contained chlorophyll and bacteriochlorophyll signatures rather than heme B.

The discovery has wider implications for molecular-level paleontology. Further study could help advance understanding of blood evolution, dinosaur metabolism, and ancient animals' activity levels. Notably, the researchers clarified that while red blood cells and heme molecules have been preserved, no dinosaur DNA was found — the oldest direct evidence of DNA in the fossil record dates back just 1.1 million years in mammoth teeth unearthed in Siberia.

The study also notes that if such delicate biomolecules can fossilize over millions of years in harsh environments, then it is possible similar traces of life may linger elsewhere in the universe.

The research team emphasizes this is not a scenario reminiscent of Jurassic Park: although researchers have found evidence of red blood cells, they are fossilized and do not contain any traces of DNA suitable for cloning.