What colour were dinosaurs? Scientists discover how to work out pigments of animals going back 300 million years

Scientists have found a way to work out what colour the dinosaurs and other extinct animals going back 300 million years were by looking at the pigments preserved in fossils. The findings build on research from 2008 that showed how fossil melanosomes – which contain melanin – could be found in a fossilised feather.

Since this discovery, researchers have been looking at the shapes of melanosomes to work out the colours of dinosaurs and reptiles. Researchers from Virginia Tech and the University of Bristol have now shown pigment can be detected in mammal fossils too.

Lead author Caitlin Colleary said: "We have now studied the tissues from fish, frogs, and tadpoles, hair from mammals, feathers from birds, and ink from octopus and squids. They all preserve melanin, so it's safe to say that melanin is really all over the place in the fossil record. Now we can confidently fill in some of the original colour patterns of these ancient animals."

The findings were published in the journal PNAS. Scientists used a special instrument to identify the molecular make-up of the fossil melanosomes then compared them with modern melanosomes. They were also able to replicate the condition in which the fossils formed, allowing them to work out how the chemical signatures have changed over the millions of years.

"By incorporating these experiments, we were able to see how melanin chemically changes over millions of years, establishing a really exciting new way of unlocking information previously inaccessible in fossils," Colleary said.

Speaking to IBTimes UK, she said this does not necessarily make the colours identified more accurate, rather it is a tool to confirm the findings – it had previously been thought the melanosomes could have been fossilised bacteria.

She said: "We incorporated the shapes of melanosomes while also looking at the chemical structure of melanin. We basically combined the two methods so we can look at the structure of melanosome itself, while also showing chemical evidence that melanin is preserved in the fossil.

"The melanosomes shapes is very descriptive. The addition of the chemical analysis really just confirms these findings, so you can tell what colour something is by looking at the melanosome shape. That's something no one has done before. It's the first time anyone has really tried to trace degradation of melanin to try to understand how it altered over millions of years."

Fossil analysis

The team used the technique to work out the colour of two extinct species of bat from 50 million-year-old fossils. This was the first time the colours of extinct mammals has ever been described through fossil analysis. Colleary said they can use the method to identify colours of fossils going back up to 300 million years, although they would have to be very well-preserved specimens.

By working out the colours, scientists say they will be better able to understand how these extinct animals lived. "We know a lot about animals by studying colour – the colours are extremely informative when looking at modern animals," she said. "We can learn about the environments they lived in, how they protected themselves, how they tracked mates – being able to access that sort of information from those fossil records would be very exciting."

Colleary also said the method will better allow scientists to accurately colour extinct animals like the dinosaurs in the future. "I want to see what colour everything was," she said. "If you think about all of the books you've seen pictures of dinosaurs, they've just made that up. I just want to colour in every animal you can think of. I think the more studies happen with this line of research, the more we will be able to understand what animals looked like before.

"It's interesting because now we are looking at dinosaurs with feathers, and that's obviously very different from what was in the books when I was a kid. We're learning a lot about what animals actually looked like and I think that will just continue to evolve."