Birds have been around for a good 150 million years, but they likely looked very different from the birds we see today. Some paleontologists have wondered if early birds were even able to fly. A newly discovered fossil clears that up.
There isn't much to the fossil found recently in Spain. It isn't big and it isn't complete. It is merely the wing of a small bird that lived 125 million years ago. Despite the modest size of the find, it provides scientists with big clues. Most fossils of ancient birds don't look much like modern birds. Guillermo Navalón, one of the authors of a paper about the find, describes ancient birds as being "skeletally quite different from their modern counterparts."
This wing looks like a modern bird's wing. The fossil shows not the bones but the structure of the soft tissue -- the skin, the placement of the feathers, and the musculature. The fossil is notable for having fine muscles which would have controlled the positions of feathers while the bird was in flight. This is a characteristic seen in modern birds, which manoeuvre quickly through the air. Based on past skeletal remains, some doubted that ancient birds could do the same. This find shows that they probably were nimbly flapping around among the dinosaurs.