Science: Penguin Fossil Paints Portrait of Ancient Feathers

The fossil feathers of a 36 million year-old penguin give clues to some of its modern features, a new Science study reports.

"Before this fossil, we had no evidence about the feathers, colors and flipper shapes of ancient penguins. We had questions and this was our first chance to start answering them," said Julia Clarke, lead author and paleontologist at The University of Texas at Austin.

Artist reconstruction of Inkayacu paracasensis.

[Illustration: Katie Browne, U.T. Austin; © Science/AAAS]

Found in the feathers of living birds, the packets of color pigment called melanosomes were first reported in fossil bird feathers in 2008. These bits of color are tiny—a hundred melanosomes can fit across a human hair. Now, Clarke and colleagues show that fossilized melanosomes can help determine the evolutionary development of penguins.

Penguins are highly adapted for their cold, aquatic environment. Changes in their wings and feathers have allowed rapid swimming (aquatic "flight") and protection from near-freezing water, yet there is very little data to explain how penguin feathers evolved.

In the study, the researchers analyzed a 36-million year-old penguin with well-preserved feathers found in Peru. While the outside appear of the ancient penguin's wings and feathers look like what is seen in present-day penguins, the team found that the melanosomes in its feathers did not.

Specifically, the ancient penguin had much smaller melanosomes resembling the pigment cells of many other aquatic birds, but not today's penguins. The results hint that the shape and form of the ancient penguin's feather evolved before microscopic changes that affect properties like strength and water resistance, which may help explain how and when penguins adapted to life in water.

Nadia Ramlagan

30 September 2010