67-million-year-old fossil upends bird evolutionary tree

A 67-million-year-old beak bone has upended the evolutionary tree of life for birds. Most modern birds have flexible bony palates that allow them to move their upper beak independently of their skull. Just a few — including emus, ostriches and kiwis — have fused palates and fixed beaks. It had been assumed that the ancestors of all modern birds were like these ‘ancient-jawed’ palæognaths. But a tiny bone encased in rock suggests that flexible jaws came first.