This video says about itself:
Dinosaur’s Feathered Tail Found Remarkably Preserved in Amber | National Geographic
8 December 2016
An extraordinarily well-preserved dinosaur tail, with a fluffy covering of feathers, lies trapped within a piece of amber. The animal it belonged to would have lived about 99 million years ago. Researchers from China and Canada identify it as a juvenile of some type of coelurosaur, a group that includes birdlike dinosaur species that walked on two legs. But because the bones of the tail are flexible and not fused as in a bird’s tail, the specimen must be a terrestrial dinosaur rather than an actual bird. Lida Xing, first author of the study announcing the discovery, found the amber for sale in a northern Myanmar (Burma) market.
From Smithsonian.com in the USA:
This 99-Million-Year-Old Dinosaur Tail Trapped in Amber Hints at Feather Evolution
The rare specimen provides new insights into how feathers came to be
By Danny Lewis
December 8, 2016 12:37PM
Once thought to to be scaly-skinned beasts, many dinosaurs likely sported fantastical feathers and fuzz. Though early ancestors of birds, many pieces of their evolutionary timeline remain unclear. But a recent find could fill in some of these gaps: the tip of a fuzzy young dino’s tail encased in amber.
In 2015, Lida Xing, a researcher from the China University of Geosciences in Beijing, was wandering through an amber market in Myanmar when he came across the specimen on sale at a stall. The people who had dug it out of a mine had thought that the fossilized tree resin contained a piece of some sort of plant and were trying to sell it to be made into jewelry. But Xing suspected that the hunk of ancient tree resin could contain a fragment from an animal and brought it to his lab for further study.
His investment paid off.
What looked like a plant turned out to be a tip of a tail covered in simple, downy feather. But it’s unclear exactly what kind of creature it belonged to. Researchers took a closer look at the amber piece using CT scans and realized that it belonged to a true dinosaur, not an ancient bird. The researchers detailed their find in a study published in the journal Current Biology.
“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,” Ryan McKellar, a researcher at the Royal Saskatchewan Museum and co-author of the study says in a statement. “Instead, the tail is long and flexible, with keels of feathers running down each side.”
Without the rest of the skeleton, it’s unclear exactly what kind of dinosaur this tail belonged to, though it was likely a juvenile coelurosaur, a creature closely related to birds that typically had some kind of feathers. And what’s most intriguing about this 99-million-year-old fossil are the feathers. In the past, most information on dinosaur feathers has come from two-dimensional impressions left in stone or feathers that weren’t attached to the rest of the remains.
See also here.