Study Reveals Sudden Color Burst in Feathered Dinos 150 Million Years Ago
By Lenny Pierce on February 14, 2014
While I still feel that Dr. Alan Grant remains a visionary in the world of paleontology, the notion that birds are descended from dinosaurs has become old news to most of us. What remains a relatively new idea to plenty of us is that some of those dinosaur ancestors already had feathers before they became the birds we see today. It has been relatively unclear what these early feathers would have looked like, but recent studies have suggested that from the very beginning, they may have been just as bright an colorful as those belonging to their modern descendants.
Researchers came to this conclusion after looking at melanosomes of feathers. Melanosomes are organelles which contain a common light absorbing pigment called melanin. It is the shape of these melanosomes that determines the color of a feather. What they found was that about 150 million years ago, there was a sudden increase in diversity of melanomes, and thus a greater diversity of feather color. This time period is important, because this is about the same time that truly bird-like feathers (barbs branching off from a single shaft) first arose in dinosaurs at all. What this means is that the feathered forefathers of modern birds – a lineage called Maniraptora – may have had all of the bright coloration that birds have today, and yes, that includes Toucan Sam.
Alvarezaurus was an early member of the Maniraptora lineage. (Wikipedia)
The melanomes found in the study are those which account for the black, brown, and gray pigments which can create an iridescent effect on the surface of a feather. “These are the pigments that would make feathers look iridescent, or glossy,” said the study’s co-author Julia Clarke of the University of Texas at Austin. This means that Maniraptora 150 million years ago may have had some of the shimmery qualities of hummingbirds, birds of paradise, or The Crow (1994).
The early ancestors of birds had the proper building blocks for iridescence, meaning they could have shown of glossiness found in modern birds like the violet bellied humming bird. (Adam Riley / Rockjumper Birding Tours)
While the reason behind why this melanin spread so quickly remains something of a mystery, there is one theory that is favored by the researchers. Because many of the genes involved in melanin coloration production are also associated with more vital systems like food intake and defense, researchers have theorized that this sudden color explosion may be linked to changes in these animals’ diets and/or metabolism. Studying this potential link could give scientists clues as to what was happening in the bodies Maniraptora as they were evolving into birds, and why it was happening so fast.
The original study is published in the Feb. 13 edition of Nature and the Spring 2014 issue of Ranger Rick.