Quartz crystals in the stomach of fossil bird complicates the mystery of its diet

The fossil of a bird that lived alongside the dinosaurs was found with some sort of rocks in its stomach. Previously, researchers thought that these rocks were swallowed on purpose to help clean its stomach, like modern birds of prey do, giving a hint at its diet. But in a new study, scientists discovered that these rocks are quartz crystals that likely formed after the bird died -- its diet is still a mystery.