Fossilized Red Blood Cells Found in 115-Million-Year-Old Dinosaur Bone

Scientists have found what they consider the strongest evidence yet of red blood cells in a dinosaur fossil, discovered inside the right leg bone of a medium-sized dinosaur that lived in Brazil about 115 million years ago during the Cretaceous period. Researchers identified microscopic structures in the bone of an "Aratasaurus museunacionali" dinosaur that appear to be fossilized red blood cells, along with chemical evidence of "heme," an iron-containing molecule linked to hemoglobin that gives blood its red color. The evidence was found in vascular canals of a young dinosaur estimated at four years old and about 3.1 meters long. Lead author Cleiti Grace of Curtin University in Perth, Australia, said the findings represent a "metallic and molecular echo of ancient biology," noting the rarity of soft tissue preservation in fossils. The study was published in the journal "Proceedings of the National Academy of Sciences," and researchers suggest such cellular and molecular evidence could add new biological insights beyond what bones and teeth typically reveal.