What Colour Were Dinosaurs? How Scientists Read Colour From Fossils

Every dinosaur picture you have ever seen involved a guess. Bones tell us an animal’s shape and size, but not its colour. For over 150 years, artists painted dinosaurs green, grey or brown, mostly by comparison with crocodiles and lizards. Then, in 2010, scientists found a way to read the colours of some dinosaurs directly from their fossils.

Pigment capsules in fossil feathers

The key is melanin, the pigment that colours human hair and skin and many bird feathers. In animals, melanin is packed into tiny capsules called melanosomes, less than a thousandth of a millimetre long. Melanosomes come in different shapes:

• Long, sausage-shaped melanosomes contain eumelanin, which produces black and grey colours.
• Small, round melanosomes contain phaeomelanin, which produces reddish-brown, ginger and rusty colours.
• Feathers with no melanosomes are usually white.
• Some arrangements, like flattened melanosomes in neat layers, produce iridescent sheens.

In the fine-grained rocks of northeastern China, many small feathered dinosaurs have been found with their feathers preserved as dark films. Under an electron microscope, scientists discovered that these films are packed with fossil melanosomes. By measuring their shapes and comparing them with those of living birds, they could estimate the original colours.

Dinosaurs in colour

• Sinosauropteryx: in 2010, a team led by Fucheng Zhang found that this small predator had a striped tail of alternating ginger-brown and white bands, a darker back and a lighter belly.
• Anchiornis: the same year, a team led by Quanguo Li reconstructed the whole plumage of this crow-sized dinosaur: mainly grey and black, with white wing feathers tipped in black and a reddish crest, looking rather like a modern woodpecker.
• Microraptor: in 2012, the four-winged Microraptor was shown to have glossy, iridescent black feathers, like a crow or starling.
• Psittacosaurus: in 2016, Jakob Vinther and colleagues studied the preserved skin of this small horned dinosaur and found countershading: a dark back and pale belly. That pattern helps animals hide by cancelling out shadows, and the details suggested it lived in a forest with diffuse light.

What we still don’t know

Colour reconstructions have limits. Melanin is durable, so blacks, greys and reddish-browns can be detected. But many bright colours in modern birds, like the reds of cardinals or the yellows of canaries, come from carotenoid pigments obtained from food, which rarely survive fossilisation. Some colours also come from microscopic structures that may be distorted over millions of years. So reconstructions show only part of the picture.

And most dinosaurs, including T. rex, have never been found with the right kind of preserved skin or feathers. Their colours remain unknown.

Why colour matters

Colour tells us about behaviour and habitat. Striped tails and bold crests suggest display, perhaps to attract mates or recognise rivals. Camouflage patterns like countershading reveal where animals lived and that they had predators to hide from. And the fact that these patterns look so bird-like is another reminder that birds are living dinosaurs.

In short

• Dinosaur colours were long guesswork; bones don’t preserve colour.
• Fossil feathers and skin can contain melanosomes, tiny pigment capsules.
• Sausage-shaped melanosomes mean black or grey; round ones mean reddish-brown.
• Sinosauropteryx had a ginger-and-white striped tail; Anchiornis had black-and-white wings.
• Microraptor was iridescent black; Psittacosaurus was countershaded for camouflage.
• Bright carotenoid colours rarely survive, and T. rex’s colour is still unknown.