University of Texas at Austin

Wednesday, March 30, 2011

Scientific teamwork revealed new penguin’s colors

Worldwide collaboration discovers, elucidates ancient species found in Peru

Prof. Julia Clarke, paleontologist studying the origin and evolution of birds and related dinosaurs..

Prof. Julia Clarke, paleontologist studying the origin and evolution of birds and related dinosaurs..

The discovery process started with the eagle eye of a young fossil hunter in the Peruvian desert, continued with the meticulous work of fossil experts from Texas, Peru and North Carolina in a Lima laboratory and incorporated techniques recently developed in Connecticut and Ohio.

The result was the identification of a new species of giant penguin from 36 million years ago. It was the first penguin fossil with preserved evidence of feathers. The discovery was the cover story in the Nov. 12, 2010 issue of Science.

The project came together under the direction of Julia Clarke, a paleontologist in the Jackson School of Geosciences at The University of Texas at Austin, who was the principal investigator.

With the fossils, paleontologists could reconstruct the penguin’s size and shape from its bones, but it was the feather evidence that opened a broad new swatch of investigation.

Watch Julia Clarke’s “Hot Science-Cool Talks” presentation on dinosaurs.

Read about paleontology at the Jackson School of Geosciences.

Named Inkayacu paracasensis, the penguin was striking in several ways. It was bigger than today’s penguins with a swimming length of five feet. It had a narrow head and elongated beak.

An artist's rendition of Inkayacu paracensis diving. Illustration by Katie Browne

An artist's rendition of Inkayacu paracensis diving. Illustration by Katie Browne

Besides a distinctive profile, the researchers found that its feathers were distinctive, at least compared to today’s penguins.

Its feathers, the researchers estimated, were dominantly reddish-brown and gray rather than the black-and-white of current penguins.

How the team of scientists elicited this information from a set of fossilized bones that had been buried for millions of years is a story in itself.

The scientists were from The University of Texas at Austin, the Museum of Natural History in Lima, Peru, North Carolina State University, the University of Akron and Yale University as well at the University of Washington Burke Museum and the University of Toulouse in France.

Fossil found and prepared

The present-day story of Inkayacu paracasensis begins in 2007.

Ali Atamirano and Clarke (right) at the fossil site in Peru. Photo by Drew Eddy.

Ali Atamirano and Clarke (right) at the fossil site in Peru. Photo by Drew Eddy.

Ali Altamirano, an undergraduate student working at the Museum of Natural History in Lima, Peru, made the discovery in Paracas National Preserve. The preserve is on the Pacific Ocean about 150 miles south of Lima.

Altamirano was a co-author on the Science paper, but not because he found the fossil, Clarke said. His involvement extended into the lab.

“He actively participated in all aspects of the anatomical study of the fossil,” she said. She has hopes Altamirano will come to Texas for his Ph.D. studies.

The fossil bones were encased in a block of sandstone the size of a kitchen table. It had taken millions of years for the bones to set in the stone and it would take a while, though not nearly as long, to get them out.

The fossil was prepared and studied at the Museum of Natural History, where Rodolfo Sala-Gismondi, head of the vertebrate paleontology lab, oversaw its collection and removal from the rock.

“That’s a process that takes months,” Clarke said, describing the process as it unfolded. “So we have to wait. These fossils are from sediments that are very salty and unstable so Rodolfo and his team have to soak the specimens to stabilize them. It’s a long process.”

Working through the stone to the bones is painstaking.

“We open up the top of the block and start preparing down on the block using these pointed tools, pen vises, and just going very, very slowly around the bone, closer to the bone to see what we might find,” Clarke said.

Daniel Ksepka, an assistant professor at North Carolina State University, also played a key role in analyzing the penguin’s anatomy, Clarke said.

He had been a graduate student at Columbia University when the project started. Then he became a post-doctoral researcher in Clarke’s lab. Now he’s at N.C. State, where Clarke was before coming to Texas.

Clarke and Ksepka worked on the anatomical analysis and the specimen’s place in penguin evolution.

Ksepka wrote about the Inkayacu discovery on his blog.

Giving color to feather

While this international team was uncovering feathers and fossil bones millimeter by millimeter and identifying the new penguin species in Lima, researchers at Yale made a discovery that would add another layer of knowledge to the Inkayacu project.

Comparison of melanosome proportions and body contour feather morphology in (A and B) Inkayacu paracasensis and (C and D) representative extant penguins. Image from Science.

Comparison of melanosome proportions and body contour feather morphology in (A and B) Inkayacu paracasensis and (C and D) representative extant penguins. Image from Science.

Jakob Vinther, a graduate student at Yale working with faculty members Richard Prum and Derek Briggs, recognized in 2008 that tiny structures in fossil feathers that were previously thought to be bacteria were actually melanosomes. Melanosomes contain melanin, the light-absorbing pigment that gives color to fur and feathers. The shape of melanosomes, either round or more elongate, was known to be related to feather color.

Clarke was visiting Yale in 2008 and Vinther, Prum and Briggs filled her in on the melanosome breakthrough.

“So we started a collaboration, which first led to China and study of a new feathered dinosaur,” she said.

To complete their analyses of melanosome data from the dinosaur fossil they turned to Matthew Shawkey, an assistant professor of biology at the University of Akron, who was developing a library relating characteristics of melanosomes to the colors they produce in living birds.

That work resulted in a Science paper in early 2010 reporting the first color map of an extinct dinosaur, Anchiornis huxleyi, which had been found in China.

Shawkey, post-doctoral researcher Liliana D’Alba and the library, Clarke said, “proved instrumental in coming up with a color map for the feathered dinosaur.”

They did the same for Inkayacu.

Tying it together

This is where the two sides of the project came together.

“When we were in Lima studying the feathers we were focusing on their shape, the shape of the flipper and the implications for the early evolution of penguin feathering, but we were also asking ‘Have we thought of all the ways we can look at these feathers, analyze them?’” Clarke said. “And at the same time, colleagues at Yale were pioneering a novel way of looking at fossil feathers. Those two projects melded.”

With the addition of the melanosome data, Inkayacu was much more articulate about itself than it might have been.

Such developments, Clarke said, make it a thrilling time in penguin paleontology.

“We have been able to paint a much fuller picture of the evolution of penguin feathering, working with feather shape, distribution and now color,” she said. “It is a long complicated road from a field discovery to a final paper. I’ve been lucky, especially for the support of my Peruvian colleagues. Without our field collaboration and the discovery of new fossils we can’t even start to answer some of the most engaging questions.”

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