In recent years, though, science has come closer and closer to figuring out how to discover the colors of long-dead species. In 2008, a team at Yale University identified melanosomes, the organelles that manufacture the pigment melanin within a cell, in a fossilized feather. Because melanosomes differ by shape according to the type of melanin they produce—eumelanin, for example, can be black or brown depending on concentration, while pheomelanin is red—the researchers hypothesized that the appearance of a melanosome could be used to infer the color of the animal it belonged to.

But even better than inferring is knowing for sure. In a study published today in the Proceedings of the National Academy of Sciences, researchers from Virginia Tech and the University of Bristol analyzed the chemical structure of melasonomes from several different fossilized species, confirming the correlation between shape and shade—and, they believe, putting lingering doubts about the method to rest.

“People had questioned whether you could use the shape of the melanosome to tell anything about the color, because it’s been through a lot. Millions of years in the ground is obviously going to take a toll,” said Caitlin Colleary, a Ph.D. candidate in geological sciences at Virginia Tech University and the study’s lead author. “So by finding traces of the chemical melanin in association with these structures, we’ve basically confirmed that you can use the shapes of the melanosomes themselves to tell what color something was.”

While past research has examined the melasonomes of dinosaurs and other fossilized reptiles, Colleary and her colleagues included two species of extinct bat in their study, making them the first to identify the color of a mammal through its fossil record. And because color can offer clues to an animal’s environment and behavior, the findings also open the door for an understanding of extinct species that goes beyond the aesthetic.

“It’s so funny to think about how we grew up looking at these textbooks and books that had pictures of dinosaurs in them,” Colleary said, “but we didn’t know what color they actually were. So there are so many animals we should be able to draw with confidence.”

“For me personally, color patterns are also really interesting,” she added. “I’d really like to see the extinct relatives of giraffes, because giraffes have such a distinct color pattern. So it would be really cool to see what those guys look like.”

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