Hidden Fossil, Flying Dragon

Around 120m years ago, as the dinosaurs neared the climax of their dominion, high above their heads an extraordinary creature flitted from tree to tree. The bizarre lizard, named the "flying dragon" by its Chinese discoverers, glided using a flap of skin spread over eight ribs.

The find is remarkable because almost all gliding species, such as "flying" frogs and squirrels, use a membrane spread between their toes or between their body and legs to generate lift. Only two other species evolved the rib-gliding tactic. Xianglong zhaoi is also the first lizard fossil with gliding ribs to be found.

Li Pipeng and colleagues at the Shenyang Normal University in north-eastern China say: "Gliding is an energetically efficient mode of locomotion that has evolved independently, and in different ways, in several tetrapod groups."

The fossil lizard, which was found in Liaoning, north-eastern China, is 15.5cm (6in) long, including a 9.5cm tail. But its strangest feature is eight elongated ribs around 4cm long, covered in a skin flap. The fossil's extraordinary preservation meant scientists could see details of the flap as well as the bones.