In January, the telephone rang non-stop in Xu Xing's cluttered office at the Institute of Vertebrate Palaeontology and Palaeo-anthropology in Beijing. Reporters from Europe, Japan, the US and Brazil called wanting to talk about the 'four-winged dinosaur' he had helped discover. Sounding improbably bizarre, the animal that lived about 125 million years ago had feathered limbs, which it used to glide from tree to tree. Dr Xu, lead investigator of a group of international scientists, believed the find might hold the key to advancing our understanding of the link between dinosaurs and birds. An article he wrote on the topic was published in the prestigious British scientific journal Nature. Scientists have debated for more than a century whether birds evolved from dinosaurs. Dr Xu and his collaborators studied six pieces of fossils containing a Microraptor or Microraptor gui, a small, fast-running fuzzy dinosaur with claws that could grasp branches. They theorised it could be the first tree-dwelling dinosaur, representing an intermediate stage in the evolution of flight. 'Capturing the moment that dinosaurs took flight has been my dream,' he said. The 34-year-old scientist is probably the best known Chinese palaeontologist, and has published 12 detailed studies in leading international scientific journals. The study of the four-winged dinosaur was based on his earlier research on the Microraptor zhaoianus - a two-legged meat-eating dinosaur with bird-like features. Measuring just 39cm, it was the smallest dinosaur ever discovered. With each new discovery pushing closer to the creatures being able to fly, Dr Xu was hopeful that he could one day firmly establish the origin of birds. His name came to the attention of the international media in 1999 when he produced conclusive evidence that a fossil on which an article in the National Geographic magazine was based was a 'composite'. The highly publicised hoax caused a great deal of embarrassment for the publication. The story with its many twists and turns began when an American couple bought a piece of fossil from a dealer containing an Archaeoraptor that had the body of a primitive bird and the tail of a dinosaur. Combining with a Canadian scientist and the art director of National Geographic, they invited Dr Xu to join the study to 'add an exotic touch to the all-American cast', according to a report specially commissioned by the magazine. It was Dr Xu who exposed the fake. He examined the two slabs of stone between which the bones were sandwiched and proved that the fossil had the tail of a Microraptor zhaoianus glued to a primitive bird later identified as Yanornis martini. All the fossils had come from Liaoning. Looking back at the episode, Dr Xu said the scientific community consists of people whose vanity and greed were often at play as much as their quest for knowledge. He described his discovery of the hoax as good luck. 'The probability was so small,' he said. In addition to his scientific work, Dr Xu devotes his time to teaching people about dinosaurs. He is a frequent guest on science programmes on CCTV and the author of The Surviving Dinosaur, in which he sums up major discoveries of birdlike dinosaurs that roamed the Earth for 170 million years before they became extinct.