A new study has shone light on a question that has long puzzled palaeontologists: could the winged, bird-like Jurassic dinosaur Archaeopteryx actually fly? From detailed analysis of its fossil bones, researchers now think that Archaeopteryx was capable of flight, and that it probably flew like a pheasant, flying in short bursts of active flight.

Using powerful X-ray beams to look inside Archaeopteryx’s bones, the research team showed they were almost hollow, like those of modern birds. Measuring the sizes and shapes of the wing bones, researchers found they matched those particular types of bird that flap their wings to fly short distances or in bursts, such as pheasants or quails. Archaeopteryx's bones had particularly thin walls, in some cases no more than a millimetre thick—a feature the dinosaur shared with the modern “burst flying” birds.

The question of whether Archaeopteryx was a ground dweller, a glider or capable of full flight has been the subject of debate since the first fossils were found in the 1860s. Some experts thought Archaeopteryx could not fly at all, while others believed it was able to get airborne much as modern birds do. Others still thought that the creature used its claws to climb trees, then simply glide back down again.

According to lead researcher Dennis Voeten of the European Synchrotron Radiation Facility (ESRF) in Grenoble, France (where the high-resolution X-ray imaging took place), "If they have to fly to evade a predator they will make a very quick ascent, typically followed by a very short horizontal flight and then they make a running escape afterwards." Archaeopteryx might have had an unusual flapping style, bringing its wings forwards and upwards before pulling them back down, like the butterfly stroke used by swimmers.

Archaeopteryx lived about 150 million years ago in what is now southern Germany. At that time, the region was a tropical archipelago—a group of small islands. It may have used its ability to fly to escape from predators in a confined space, or hop from island to island. Similar in size to a magpie, Archaeopteryx had feathered wings like a bird, but also the sharp teeth and a long bony tail of a dinosaur. Once thought to be the first bird, palaeontologists now consider it to be a feathered dinosaur and not a direct ancestor of birds.