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A recent fossil find reveals that penguins might not have always been so formal in their feathery attire. Rather, some penguins of the late Eocene were likely cloaked in reds, browns and grays rather than the classic black and white, according to a new report. Aside from painting a more accurate picture of ancient aquatic avifauna, analysis of ancient pigment-giving particles can provide clues about feather—and the animal's—evolution.
The newly described species on which the fossil feathers were found, Inkayacu paracasensis, lived some 36 million years ago in what is now Peru. The extinct bird was roughly twice the size of an emperor penguin (Aptenodytes forsteri), measuring about 1.5 meters long and weighing between 54.6 and 59.7 kilograms, according to the new paper, published online September 30 in Science.
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Aside from the bird's mass (it's noted as among the largest of known ancient penguin species), its feathers' nano-sized color compounds were also a different size, shape and distribution than those in modern-day penguin feathers. These melanin-containing structures are known as melanosomes and have been found in dinosaur fossils more than 100 million years old. After studying melanosomes in six I. paracasensis samples, the researchers noted that the ancient particles were both wider and more densely clustered than those found in extant species, an observation that provides clues about coloring as well as physical characteristics.
"Before this fossil, we had no evidence about the feathers [or] colors…of ancient penguins," Julia Clarke, a paleontologist at the University of Texas and coauthor of the report, said in a prepared statement.
Some modern-day penguins are outfitted in browns and grays as babies, but researchers are confident that the I. paracasensis specimen was not simply passing through a phase. "Features of the bones tell us that this particular fossil was a fully grown adult, not a juvenile, so finding brown and gray colors was a surprise," Dan Ksepka, an assistant professor of marine, earth and atmospheric sciences at North Carolina State University and coauthor on the report, said in a prepared statement.
But the color change might not just have been for show. A penguin's feathers have to be strong, as they face strong forces in the animals' watery dives. "Melanin confers resistance to fracture, important to materials like feathers," noted the authors of the study. So a change from brown to black could have been functional at a nanoscale as body size or environment changed.
"By looking at the way these fossilized feathers differ from those of living penguins, we may be able to learn more about why species like the Inkayacu became extinct," Ksepka said.
Another researcher involved in the work was primarily excited about coloring in such an ancient animal: "Most of all, I think it is simply just cool to get a look at the color of a remarkable extinct organism," Yale University's Jakob Vinther said in a prepared statement.
Images courtesy of Katie Browne/U.T. Austin