Paleontologists have just uncovered the remarkably pristine cranium of an ancient bird along with three partial skulls. These remains combine modern and primitive features in surprising ways to capture a fascinating moment in avian evolution.
The Ichthyornis fossils starkly contrast the skeletons of current birds. Modern birds have less musculature in their jaw and larger braincases than their predecessors. Whereas today’s birds have lightweight, toothless snouts, the fossils have large, toothed upper jaws—more comparable to those of dinosaurs. The Ichthyornis specimens even have openings in the top of their skulls, just like in T. rex fossils, to allow for large muscles.