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Pigment Identified in Ancient Animal Fossils

FILE - A fossil of Collinsium ciliosum, a Collins' monster-type lobopodian found in the early Cambrian Xiaoshiba deposit of southern China, is seen in a picture provided by Jie Yang.

While fossils allow researchers to determine the size and shape of extinct animals, determining their color was guesswork until now.

Scientists from Virginia Tech and the University of Bristol say they’ve been able to discover that two extinct species of 50 million-year-old bats were reddish brown in color based on their fossils.

"We have now studied the tissues from fish, frogs, and tadpoles, hair from mammals, feathers from birds, and ink from octopus and squids," said Caitlin Colleary, a doctoral student of geosciences in the College of Science at Virginia Tech and lead author of the study in a statement.

"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 color patterns of these ancient animals."

Researchers added that the technique they’ve used could be used for fossils up to 300 million years old.

The breakthrough came when researchers determined that what was believed to be fossilized bacteria were something called melanosomes, a part of a cell that contains melanin, which gives color to hair, feathers, skin and eyes.

These were first described in 2008 by Jakob Vinther, a molecular paleobiologist at the University of Bristol and the senior author of the current study.

"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 little sausages and we can see that this trend is also present in the fossils," Vinther said in a statement. "This means that this correlation of melanin color to shape is an ancient invention, which we can use to easily tell color from fossils by simply looking at the melanosomes shape."

Researchers were also able to determine that the melanosomes are chemically different as well, which allowed them to compare modern and ancient melanosomes.

"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.

Determining the color of ancient animals will be key to understanding how life evolved, researchers said.

"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," Summons said. "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."

The research was published this week in the Proceedings of the National Academy of Sciences.