Scientists have found structures that look like fossilized red blood cells in the leg bone of a 115-million-year-old dinosaur called Aratasaurus museunacionali. This meat-eating dinosaur lived in what is now northeastern Brazil. The bone was discovered in a mine in 2008. A research team led by Kliti Grice from Curtin University in Australia studied the fossil carefully. They saw many tiny round shapes inside the old blood vessel channels of the bone. Chemical tests also found heme, a molecule that is part of blood. This is the oldest evidence of dinosaur red blood cells found so far. The study was published in the journal PNAS on 2 November 2026. The finding shows that some soft body parts can survive in fossils for a very long time.
Who: An international team of scientists led by Professor Kliti Grice from Curtin University in Australia.
• What: Structures that appear to be mineralized red blood cells, along with chemical evidence of heme (a key part of blood), found inside the leg bone of the dinosaur Aratasaurus museunacionali.
• When: The dinosaur lived about 115 million years ago (Early Cretaceous). The fossil bone was found in 2008. The scientific study was published on 2 November 2026.
• Where: The fossil comes from a gypsum mine in the Romualdo Formation near Santana do Cariri, Ceará state, northeastern Brazil. Most of the research was done in Australia.
• Why: To learn how soft tissues and molecules can be preserved for millions of years, and to better understand the biology of dinosaurs.