Scientists have made an unusual discovery inside fossilised dinosaur droppings: a bird feather. It comes from a period 66 million years in the past. It is thought to have been left by a Tyrannosaur. The feather is exceptionally well preserved, which is a rare find. It provides a clear glimpse into what the dinosaur ate. The feather shows the dinosaur had eaten a bird. The discovery may help us understand bird survival after the extinction. A new study lays out these findings. It gives us a snapshot of ancient predator-prey interaction.