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Penguin fossil paints portrait of ancient feathers

Artist reconstruction of Inkayacu paracasensis.
Illustration: Katie Browne, U.T. Austin

The fossil feathers of a 35 million year-old penguin found in Peru give clues to how these plump birds got some of their modern features, a new study reports. The study is being published online September 30th, by the journal Science at the Science Express web site.

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, Julia Clarke from the University of Texas at Austin and colleagues show that fossilized melanosomes can help determine the evolutionary development of penguins.

Julia Clarke excavating a fossil in Peru's Paracas Reserve.
Image courtesy of N. Adam Smith, U.T. Austin

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 35 million year-old penguin with well-preserved feathers. While the outside appearance 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 melanosomes that resembled 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.