To the right is a picture of the Sinosauropteryx fossil. You can see the banding on the tail pretty clearly. But how did scientists determine that the dark bands were ginger? Using an SEM (a scanning electron microscope), they searched for tiny structures called melanosomes. The shape of a melanosome determines color. Dark colors - dark brown, black, and grey - are determined by long, skinny melanosomes. Lighter colors, primarily russet and ginger, are characterized by ball-shaped melanosomes. In Sinosauropteryx feathers, the melanosomes are primarily the round variety. It's a really cool discovery, that gives paleoartists the chance to draw this:
It's not just an educated guess as to this dinosaur's color. This is most likely what Sinosauropteryx really looked like. This discovery raises the possibility of examining other fossil feathers (and perhaps even fossil skin?) to learns, once and for all, what color the dinosaurs were.
Source: BBC News- Dinosaur had ginger feathers