Just like the evolution of our TV and movie screens, the technology that scientists deploy today has become better at filling in ancient Earth's coloring book — the past is no longer limited to black and white.
Experts learned that some fossils can keep evidence of the skin color of animals from multiple pigments. In fact, an exquisitely preserved fossil skin of a 10 million-year-old snake has helped a team of scientists reconstruct the ancient reptile, revealing a wide range of hues.
True Colors
Paleobiologist Maria McNamara, first author of the study, said that prior to this research, the only viewpoint for color being preserved in fossils was from organic remains related to melanin.
When melanin on the skin lasts as organic material, scientists could see blacks, muddy reds, and browns, helping in reconstruction. Past studies have found that no other colors have survived fossilization.
The 10 million-year-old snake's fossil, however, is different. The prehistoric reptile had a back patterned in green and dark brown, as well as a lighter belly, researchers found.
How did that happen? McNamara and her colleagues said the snake skin was preserved in calcium phosphate, which has the ability to preserve details on a subcellular level.
The snakeskin preserved the distinctive shapes of various types of pigment cells, and this would have created iridescence, greens, yellows, browns, and blacks while the snake was alive.
Although the pigment cells have now decayed, the mineralized cell shapes specific to each kind of pigment offer enough evidence to recreate colors.
Examining the Fossilized Snakeskin
McNamara, an expert from University College Cork, stumbled on the ancient fossilized snake while she was conducting her Ph.D. research on fossils from Spain's Libros site. She only recently analyzed the specimen.
Thanks to a high-energy scanning electron microscope, she and her colleagues found the mineralized skin. They then compared the shapes with pigment cells found in modern snakes in order to determine which colors each might have produced.
McNamara she was "gobsmacked" when she saw the results. "You almost can't believe what you're seeing," she said.
The snakeskin possessed three types of pigment cells in different combinations: xanthophores, which contain pterin and carotenoid pigments; melanophores, which contain pigment melanin; and iridophores, which create iridescence.
The team's findings, which have been featured in the journal Current Biology, open the door for the re-analysis of fossil bones and shells that have been detected with calcium phosphate for evidence of color preservation.
The color of an ancient animal could provide clues into some aspects of its evolution and behavior, researchers added.
