Scientists have discovered a way to detect pigment in mammal fossils to determine the colors of extinct species.
Using this new method, a team of researchers determined two 50 million-year-old bat species were reddish-brown in color, Virginia Tech reported. The method could potentially be used to paint a picture of the appearance of species dating back as far as 300 million years.
"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. "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."
In the past, researchers had mistaken melanosomes (organelles within cells containing melanin) for fossilized bacteria. The first melanosomes were recognized in a dinosaur feather back in 2008, and the shape of these melansomes has since been used to determine the color of marine reptiles and other dinosaurs. The recent finding marks the first mammal to be analyzed in this way.
"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," Jakob Vinther, a molecular paleobiologist at the University of Bristol . "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."
Besides simply looking at melanosome shape, the researchers can also determine color using instrument called a time-of-flight secondary ion mass spectrometer that reveals the chemical signature. The team used heat to recreate the conditions in which a fossil formed in order to pinpoint how melanin changes over time.
"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.
The findings were published in a recent edition of the journal Proceedings of the National Academy of Sciences.
