SCIENTISTS FIND OLDEST-EVER DINOSAUR RED BLOOD CELLS IN BRAZIL FOSSIL

Researchers have identified red blood cells in a 115-million-year-old dinosaur leg bone fragment, potentially the oldest ever found in a dinosaur. The cells came from the hind limb of Aratasaurus museunacionali, a theropod dinosaur found in Brazil in 2008. A team led by Kliti Grice at Curtin University in Perth, Australia, isolated the cells using hydrochloric acid to dissolve the surrounding rock. The dinosaur had not reached full maturity, with an estimated body length of just over three metres and a weight of about 34 kilograms. "No one has ever seen dinosaur red blood cells in high resolution before," Grice said.

A single slide of the fossil, just a fifth of a millimetre wide, contained 20 blood cells, all located within fossilised blood vessels. Liquid chromatography-mass spectrometry analysis detected haem B, a component of haemoglobin that binds to oxygen. The team tested for contamination from the surrounding sediment, which was dominated by algae. Cells found outside the bone contained chlorophyll-derived compounds, while those inside contained haem-derived molecules, indicating the internal cells were not contamination. Grice said the fossil fragments studied "are not display specimens by any means" and do not look especially interesting.

The researchers compared the cells with those of birds and crocodiles, the dinosaur's closest living relatives, and found them significantly larger. Red blood cells have been identified in dinosaur remains before, including bone fragments collected in Canada in 2015 and dated to about 75 million years old. A Tyrannosaurus rex femur found in Montana in 2005 and estimated at 68 million years old also yielded preserved red blood cells. At 115 million years old, the Aratasaurus fossil predates both of those previous finds.