Tracers:

"The color of dinosaurs is another one. Nobody knows what color dinosaurs were, because none of their skin has survived. People make guesses for the purposes of drawings, based on the current-day color of lizards and who knows what-all; but nobody really knows. But there's an answer! Dinosaurs were certain colors. The answer is out there, but it's unknowable."

(Via Proudly Serving My Corporate Masters.)