The meat-eating microraptor was a black-feathered, four-winged dinosaur. How do we know its feathers were black? The evidence is in the microraptors’ fossils. This TED Ed explains. Plus, more from Wikipedia:
How did feathers evolve?
In March 2012, Quanguo Li and team became the first scientists to determine the plumage coloration of Microraptor, based on the new specimen BMNHC PH881, which showed several other features previously unknown in Microraptor. By analyzing the fossilized melanosomes (pigment cells) in the fossil with scanning electron microscope techniques, the researchers compared their arrangements to those of modern birds. In Microraptor, these cells were shaped in a manner consistent with black, glossy coloration in modern birds. These rod-shaped, narrow melanosomes were arranged in stacked layers, much like those of a modern starling, and indicated iridescence in the plumage of Microraptor.