The Colors of a Feathered Dinosaur

A series of wonderfully preserved fossils found over the past two decades have shown us that many small dinosaurs had feathers. We don't know why; perhaps to regulate their temperatures. At any event, feathers have the useful property that, at least among living birds, the shape of the structures that hold the pigments are related to the color produced:

After all, they knew that in the feathers of living birds, some color comes from pigments called melanins. And inside of a hair or a feather, "the melanin is actually contained within a kind of capsule," says [paleontologist Mike] Benton.

The shape of the capsule depends on the color. "The black or dark brown kind of melanin goes into a somewhat sausage-shaped capsule," says Benton, while a reddish-brown kind of melanin goes into a more rounded capsule shaped like a ball.

And some of the feathered fossils are so exquisite that they actually preserve the shapes of these melanin capsules:

With this in mind, the researchers used a sophisticated, powerful microscope to peer inside primitive feathers on a turkey-sized dinosaur called Sinosauropteryx. "It's a flesh-eater. It's got sharp little teeth in its mouth, and it's got grabby little hands," says Benton. "It's a two-legged dinosaur, so very slender limbs. It's got a sort of straightish backbone and a long thin tail."

Fossils show that this tail was ringed with dark bands of primitive feathers that look like bristles. And inside these bristles, Benton and his colleagues found melanin capsules in the shape associated with the orange-brown color.

"These dark stripes, as far as we can tell, were exclusively ginger, and so this early dinosaur with its long thin tail had ginger and white stripes up the tail," says Benton.

I don't regard this finding as certain, but given that until now we knew nothing at all about the color of dinosaurs, it is still amazing.