A chunk of amber on sale in a market was found to contain a dinosaur tail, complete with feathers.

Lida Xing from the China University of Geosciences in Beijing found the specimen in Myitkyina, Myanmar. The seller thought the tail was a type of plant and hoped it would be bought be a jeweler or fossil collector.

However Dr Xing realised it could be something far more important and persuaded the Institute of Palaeontology to buy the lump for further study. It was then sent for analysis at the Royal Saskatchewan Museum in Canada.

After looking at the amber under a microscope and using CT scans, the scientists discovered it was the feathered tail of a theropod dinosaur, probably a coelurosaur, which lived in the mid-Cretaceous about 99 million-years-ago.

The feathers suggest that the tail had a chestnut-brown upper surface and a pale or white underside.

"The new material preserves a tail consisting of eight vertebrae from a juvenile," said Dr Ryan McKellar of the Royal Saskatchewan Museum.

"These are surrounded by feathers that are preserved in 3D and with microscopic detail. We can be sure of the source because the vertebrae are not fused into a rod or pygostyle as in modern birds and their closest relatives.