Fossils can tell a lot about a creature that lived long ago. They can tell us its size, what it ate, where it lived, how it hunted. Yet they cannot tell us the color of the creature. Or can they?

Today, a collaboration of scientists from the United States, the United Kingdom, Germany, Ethiopia, and Denmark have published a paper in Proceedings of the National Academy of Sciences (PNAS) that purports to accurately describe the original colors of mammals that lived 50 million years ago.

The researches used a new technique that combined previously used morphological, experimental, and chemical techniques in order to discover the colors of two bats that lived during the Eocene Epoch, approximately 56-33 million years ago.

Palaeochiropteryx and Hassianycteris are two of the earliest known bat species to exist. Both are now extinct. The team has now learned that while alive, these creatures were a reddish-brown.

The color was determined by examining microscopic spherical and oblong-shaped structures in the fossils that contain melanin. These structures have distinct shapes in both extinct and modern animals. The scientists believe the color of the creature can be inferred by these structures.

“This is a great leap forward in our understanding of how fossils are preserved. We now know how melanin is preserved and we have the methods to confidently detect it,” said Dr. Jakob Vinther of Bristol University.

Fossils dating as far back as the Carboniferous period (300 million years ago) could potentially contain melanin. There are two distinct types of melanin: one is reddish brown (phaeomelanin) and the other is black (eumelanin).

“Very importantly, we see that the different melanins are found in organelles of different shapes: reddish melanosomes are shaped like little meatballs, while black melanosomes are shaped like sausages. We can see that this trend is also present in the fossils,” said Dr Vinther. “This means that the correlation of melanin color to shape is an ancient invention, which we can use to easily determine color from fossils by simply looking at the melanosome shape.”

“How color is imparted and how we characterize it in fossils are important, because they inform us about a very specific aspect of the history of life on our planet,” said Roger Summons of the Massachusetts Institute of Technology. “For complex animal life, color is a factor in how individuals recognize and respond to others, determine friend or foe, and find mates. This research provides another thread to understand how ancient life evolved. Color recognition was an important part of that process, and it goes far back in the history of animals.”