Summary

A nondescript 115-million-year-old fragment of leg bone has yielded spectacularly preserved red blood cells, which may be the earliest ever found in dinosaurs. Red blood cells have previously been found in dinosaur remains, including 75-million-year-old bone fragments collected in Canada in 2015 and the femur of a Tyrannosaurus rex that died 68 million years ago , found in Montana in 2005.

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