How a 67-Million-Year-Old Fossil Turned the Theory of Bird Evolution Upside-Down• arclein
Most modern birds have a jointed upper jaw that allows the top half of their beak to move. But a select few, such as emus, rheas and ostriches, have a fused upper palate, making the top beak portion largely immobile. Dinosaurs also had fused palates, so researchers assumed for decades that birds like emus and ostriches had evolved first, while birds' ability to move their upper beaks developed later. Now, however, new evidence suggests scientists may have had the story backward. Based on an analysis of a prehistoric bird's skull bone, researchers propose that the jointed upper beak existed much earlier than expected, and the fused palate evolved in birds later. Researchers detailed their findings in a paper published Wednesday in the journal Nature.