Deducing feather color from melanosome shape. Panel
(a) shows the fossil in visible light, and (b) and(.c) show
progressively higher scanning EM magnifications.
Melanosomes are visible in (.c) as little moulds or pockets,
indicated by the arrows. Source: Zhang et al., Nature
A new twist on skin color paleontology has recently come out in this week's Nature. Scientists were trying to systematically look at melanosomes across the animal kingdom, and found that the remarkable correlation between melanosome shape and color holds best for mammals, birds, and (by extrapolation) maniraptoran dinosaurs. Thus it would not be so easy to assign skin color to fossils from species like T-Rex, which fall outside of these categories.