October 1, 2010
Giant Penguin Fossil Unearthed In Peru
Paleontologists have unearthed the fossilized remains of a giant penguin in Peru that lived 36 million years ago. The discovery is the first extinct penguin ever found with preserved evidence of scales and feathers, the researchers said.
The new species, dubbed Inkayacu paracasensis, or Water King, had feathers that were reddish brown and grey, distinct from the black tuxedoed look of modern day penguins.
At nearly five feet tall, the Inkayacu was one of the largest penguins ever to have lived, and was twice the size of an Emperor penguin, the largest penguin living today.
"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 Dr. Julia Clarke, paleontologist at The University of Texas and lead author of a report about the discovery.
The fossil indicates that the flipper and feather shapes that make penguins such strong swimmers evolved early, while the color patterning of living penguins is likely a more recent development.
Similar to living penguins and unlike any other bird, Inkayacu's wing feathers were radically modified in shape, densely packed and stacked on top of each other, forming stiff, narrow flippers. Its body feathers had broad shafts that streamline the penguin's shape, something also seen in modern day penguins.
Bird feathers derive some of their color from the size, shape and arrangement of nanoscale structures known as melanosomes. The researchers compared melanosomes recovered from the fossil to their extensive library of those from living birds to recreate the colors of the fossil penguin's feathers.
They found that the melanosomes in Inkayacu were similar to those in birds other than living penguins, allowing the researchers to deduce the colors they produced.
When the researchers looked at living penguins, they were surprised to find their colors were created by giant melanosomes, broader than in the newly discovered fossil and in all other birds surveyed. The melanosomes were also packed into groups that resembled clusters of grapes.
These differences caused the researchers to question why modern penguins apparently evolved their own special way to make black-brown feathers. The unique shape, size and arrangement of modern-day living penguin melanosomes would change the feather microstructure on the nano and micro scale, and melanin, contained within melanosomes, is known to protect feathers from wear and fracturing.
The researchers speculated that these shifts might have had more to do with hydrodynamic demands of an aquatic lifestyle than with coloration, and that penguin colors may have shifted for entirely different reasons related to the later origin of primary predators or other changes in the late Cenozoic seas.
"Insights into the color of extinct organisms can reveal clues to their ecology and behavior," said Jakob Vinther at Yale University, a coauthor of the report.
"But most of all, I think it is simply just cool to get a look at the color of a remarkable extinct organism, such as a giant fossil penguin," said Vinther, who first noted fossil preservation of melanosomes in bird feathers.
Inkayacu paracasensis was discovered by Peruvian student Ali Altamirano in Reserva Nacional de Paracas, Peru.
The latest findings augment previous work by Clarke and her colleagues in Peru that challenges the conventional wisdom of early penguin evolution. The Inkayacu and other discoveries indicate that there was a rich diversity of giant penguin species in low-latitude Peru during the late Eocene period about 36 to 41 million years ago.
"This is an extraordinary site to preserve evidence of structures like scales and feathers," Clarke said.
"So there's incredible potential for new discoveries that can change our view of not only penguin evolution, but of other marine vertebrates."
The findings appear in the Sept. 30 edition of the journal Science.
Image 1: Artist reconstruction of Inkayacu paracasensis. Credit: Katie Browne
Image 2: Fossil wing feathers of Inkayacu paracasensis. Credit: University of Texas at Austin
Image 3: Julia Clarke exposing wing features in the Inkayacu specimen. Credit: N. Adam Smith
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