Found in a Burmese amber mine:
The two new samples, weighing in at only 0.06 and 0.3 ounces (1.6 and 8.51 grams), contain bone structure, tracts of feathers, and soft tissue. They are the first Cretaceous plumage samples to be studied that are not simply isolated feathers, according to study co-author Lida Xing of the China University of Geosciences...More at National Geographic.
Skin, muscle, claws, and feather shafts are visible in both samples, along with the remains of rows of primary asymmetrical flight feathers, secondary feathers, and covert feathers. All are similar in arrangement and microstructure to modern birds.