The first known dinosaur tail preserved in a piece of amber was recently discovered by paleontologist Lida Xing while collection samples in Myanmar last year. Dating back to the mid-Cretaceous Period some 99 million years ago, the roughly apricot-sized piece of amber contains a 1.4-inch appendage of 8 vertebrae unmistakably covered in primitive feathers. Scientists ruled out the possibility of the tail belonging to a bird, and based on its structure believe it came from a juvenile coelurosaur, a group of dinosaurs that includes tyrannosaurs. Via National Geographic:
While individual dinosaur-era feathers have been found in amber, and evidence for feathered dinosaurs is captured in fossil impressions, this is the first time that scientists are able to clearly associate well-preserved feathers with a dinosaur, and in turn gain a better understanding of the evolution and structure of dinosaur feathers.