Dinosaur Blood Traces Found in 115-Million-Year-Old Bone

How do they know it's really blood?

Fair question. The team's first job was ruling out the boring explanations: contamination, or minerals that merely mimic biological shapes.

Their strongest card is location. The cell-like structures appear exclusively inside vascular canals — the channels where red blood cells travel in living vertebrates. The sediment surrounding the fossil contained none of them, which argues against outside contamination.

The chemistry also split cleanly. The surrounding sediment was dominated by compounds from plants and bacteria; the bone itself carried a distinct signature dominated by heme molecules. Additional analysis confirmed iron, carbon and nitrogen, plus amino acids associated with collagen.

Grice's team put microscopy, mineralogy, spectroscopy and molecular geochemistry to work, and all four pointed the same way. "We are convinced these are fossilized red blood cell structures containing traces of heme molecules," the researchers wrote.

Still, this is a single specimen. Independent replication, on this bone and others, remains the real test.

How does blood survive 115 million years?

Not fresh, that's for sure. The dinosaur was buried rapidly in a low-oxygen environment, which slowed decay. During fossilization, the microscopic red blood cells turned into minerals themselves.

A second factor may be hausmannite, a mineral that acts a bit like an antioxidant, potentially stabilizing sensitive organic molecules and slowing their breakdown. Together, these conditions preserved molecular-level biological information far longer than researchers expected.

What does this change for paleontology?

The cell-like structures look somewhat larger and more rounded than red blood cells in modern birds and crocodilians. That could mean distortion during fossilization. Or — more interesting — it could mean non-avian dinosaurs had differently shaped red blood cells than their bird relatives. Further research will have to settle it.

The bigger implication is practical. If soft tissues and blood-derived molecules can survive more than 110 million years under the right conditions, then museum drawers around the world may hold an enormous, largely untapped resource. Many of those fossils aren't display pieces. Even so, they may preserve molecular, chemical and environmental information that modern analytical techniques can now read.

Specimens collected decades ago could be revisited with entirely new questions. That's the promise. The caveat: one spectacular fossil proves preservation is possible, not that it's common.

The fossil was collected and curated by researchers including Renan Bantim and Antônio Saraiva of the Regional University of Cariri, along with Juliana Sayão and Alexander Kellner of Brazil's National Museum and the Federal University of Rio de Janeiro. Collaborators also included Yuta Isaji, Calum Fox, Nana Ogawa and Noa Ohkouchi of the Japan Agency for Marine-Earth Science and Technology, and Jasmina Wiemann of Johns Hopkins University.