Pigments found on unearthed mammal fossils are now being used by researchers to determine what specific colors the extinct animals could have had during its time.
An international team of scientists from the University of Bristol in the United Kingdom and Virginia Tech in the United States made use of this method in identifying the color of two extinct bat species. Through fossil analysis, they discovered that the reddish brown hue on the 50-million-year-old animal remains described the colors of the prehistoric bats.
The researchers said that the analysis of fossil pigments can be used to determine color from well-preserved specimens as old as 300 million years.
Virginia Tech doctoral student and lead author of the study Caitlin Colleary said that they have studied tissue samples from fish, tadpoles and frogs, feathers from birds, ink from squids and octopus and hair from mammals.
She said that all of these samples are able to preserve melanin, which has been well-documented in the fossil record. These could then be used to trace the original color patterns of extinct animals.
In the study, featured in the journal Proceedings of the National Academy of Sciences, the researchers described of tiny structures found on the specimens that were initially thought to be fossilized bacteria.
Upon closer investigation, they discovered that the structures are in indeed melanosomes, which are organelles located within cells that contain melanin. Melanin is the pigment that determines the colors of hair, eyes, skin and even feathers.
Bristol molecular paleobiologist and senior author of the study Jakob Vinther first identified melanosomes in fossil feather in 2008.
Researchers have since used melanosome shapes in studying the relationship between marine reptiles, as well as in identifying the colors of dinosaurs and mammals.
Vinther pointed out that various melanin can be found in different organelle shapes. He said that reddish melanosomes often appear like tiny meatballs, while black ones look like tiny sausages. This trend can also be seen in fossils.
This suggests that the correlation of melanin color to its shape has existed since ancient times, which according to Vinther, could then be applied to easily identify the color from fossilized specimens even by merely looking at the shape of their melanosomes.
The researchers also discovered that melanosomes are distinct based on their chemical composition.
Through the use of an instrument known as time-of-flight secondary ion mass spectrometer, the team was able to examine the molecular composition of the fossil melanosomes in order to compare them with modern-day melanosomes.
They also replicated the conditions of the environment under which the fossilized specimens were formed so that they could determine the melanin's chemical alteration. Modern-day feathers were subjected to high pressures and temperatures to help the scientists understand the changing of chemical signatures while being buried for millions of years.