Fossil Feathers Revealing Extinct Moa's True Colors

July 1, 2009 -- A new stash of fossil feathers is yielding a wealth of information about Moas, the extinct giant birds that once roamed ancient New Zealand.

In a unprecedented discovery, Nicolas Rawlence of the University of Adelaide and a team of researchers found they could extract DNA from the feathers' shafts, and use the genetic material to prove the feathers belonged to four species of the flightless Moa, including the Heavy-footed Moa Pachyornis elephantopus.

The team's study was published today in the journal Proceedings of the Royal Academy B: Biological Sciences.

Scientists have been able to estimate what Moas may have looked like by extrapolating from Kiwi birds and closely-related Emus. But only a few mummified fossils of the Moas have ever been found, mostly without feathers.

Previous studies used skin cells hanging from feathers' bases to perform genetic studies. But Rawlence and his team extracted small amounts of mitochondrial DNA from from feather shafts themselves. The trick allows them to attribute random fossil feathers to individual bird species, and provide a faithful reconstruction of the Heavy-footed Moa's plumage in life.

Like their distant cousins, the Kiwis, Moas appear to have been masters of disguise. Their brown and white-tipped feathers combined to form obfuscating patterns of camouflage that would have protected them from predators, like the giant Haast's Eagle.

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"There's not much we really knew about Moa coloring," Rawlence said. "Previous reconstructions were almost there, but not all the way."

New Zealand is replete with extinct, flightless birds that remain enigmas of science. With a little luck and the right feather, Rawlence believes he can conjure the visage of a giant goose (Cnemiornis spp.), adzebill (Aptornis spp.), and other creatures.

"It's rather amazing," Allan Baker of the Royal Ontario Museum in Canada said. The new source of DNA could help researchers lay to rest an ongoing debate about whether there were 10 Moa species, the currently accepted number, or 14, as Baker has argued.

But Rawlence has his eyes set on a bigger question: How Moas may have been affected by ancient climate change.

Between around 13,000 and 12,000 years ago, Earth's climate cooled in the northern hemisphere. At almost exactly the same time, several large species of animals -- including mammoths -- rapidly died out in North America and Eurasia. Researchers have proposed everything from a comet impact to hunting by early humans to explain the extinction, but the debate rages on.

By contrast, New Zealand was human-free. If Rawlence can find evidence that Moa populations suddenly dipped at the same time as the cooling episode, he may be able to show the mammoths died a natural, climate-induced death, rather than one brought on by humans.

"If we can work out how they're responding to climate, we can begin to answer those questions," he said, pointing out that they also want to learn how healthy the Moa populations were when humans first came to New Zealand in the 13th century A.D. and began hunting them. "Were the populations stable when humans arrived, or were they already in decline?" he asked.

Thanks to their feathers, we may soon know.

Related Links:

HowStuffWorks.com: Feather

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