WorldUpdated November 2

Tests find heme in Aratasaurus bones.

Researchers tested hind-leg bones from Aratasaurus, a dinosaur that lived in what is now northeastern Brazil about 115 million years ago. The bones yielded heme, an organic compound that allows hemoglobin to carry oxygen in blood. The researchers also report what appear to be traces of red blood cells. That distinction matters: the tests found heme and apparent traces, not intact cells preserved in the fossil. The researchers see the findings as evidence of blood-cell traces—and the bone holds a chemical hint of the animal’s biology.

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Coverage started November 2