Extinct animal colours revealed

The colours of extinct animals have been revealed for the first time as ancient pigments are unlocked from fossils.

Fossils have long helped to piece together the size and shape of historical species, but the colours of these animals has, until now, been largely unknown.

By studying the microchemistry of fossilised bats, researchers at the University of Bristol have discovered that what were previously thought to be fossilised bacteria are actually structures called melanosomes.

These "pigment packets" would have been stuffed with melanin and given the living creature its colouration.

There are two types of this melanin: phaeomelanin is a reddish-brown colour, and eumelanin is black.

"These types of melanin have distinctly shaped melanosomes that we can also find in the fossils," explains co-author Dr Jakob Vinther from the University of Bristol.

"If you are ginger, then the melanosomes are shaped like tiny little meatballs. If you have black hair, we see that they are shaped like little sausages."

At less than a micron (one millionth of a meter) in length, these meatball and sausage shapes were originally mistaken for fossilised bacteria.

And, confusingly, when they analysed chemical data from the fossilised melanosomes, the Bristol team detected chemical signatures that differ from modern melanin. Speculating that this change might be the result of millions of years spent in a fossilised form, the researchers developed a technique to mimic the fossilisation process using modern melanin.

Using high pressures and temperatures, the team were able to achieve a fossilisation process that took minutes rather than millennia, enabling them to study the chemical changes that occur when melanins age.

Next the team turned to 49-million year old fossils of extinct bats from a site in Germany to try out their colouration technique. "Surprise, surprise, these fossilised bats were... brown!" jokes Vinther. "They looked exactly like modern day bats."

The findings, published in the Proceedings of the National Academy of Sciences, mean that the colours and patterns of a range of ancient, fossil animals can now be determined.