So, it's not as big of a discovery as the answer to "Which came first? The chicken or the egg?" but scientists are now saying they're confident that the feather emerged before flight.
The evidence is a recently-unearthed Archaeopteryx fossil. Archaeopteryx lived 150 million years ago and is thought to be one link between dinosaurs and modern birds. (Via Flickr / Howard Stanbury)
This is the best-preserved fossil of the raven-sized dino to date, and scientists writing in Nature say the details "contradict the hypothesis that the flapping flight of modern birds were preceded by a four-winged gliding stage."
Paleontologists have long debated what drove the evolution of feathery wings: were ancient animals already trying to fly by gliding between trees, or did they only take to the air once the nuts and bolts, like feathers, were already in place?
The new fossil helps sway the debate because, while Archaeopteryx was already known to have had feathers to help it fly, the specimen also has feathers the researchers say wouldn't be useful to any sort of air travel. (Via National Geographic)
Basically, it has what are being called "feather trousers" on its legs, and the most likely explanation is that they had some purpose other than flight, like insulation, camouflage or mating displays. (Via Flickr / Bryan Jones)
It builds the case for what National Geographic calls the "ground up" approach to flight: first, feathers, wings and other avian features evolve for other reasons, then are refined once animals start using them to actually take off.
The researchers also say this means the origin of flight likely wasn't a single event. There were lots of flightless feathered dinosaurs on the evolutionary tree, and each one of them could have eventually learned to fly at different times.