Giant Penguins Once Roamed Peru Desert, Fossils Show
for National Geographic News
|June 25, 2007|
Penguins about the size of humans roamed South America some 35 million years ago, and they didn't need ice to survive.
That's the result of a new study by North Carolina State University paleontologist Julia Clarke and her colleagues. (See a picture gallery of the giant penguin finds.)
The study, which appears in this week's issue of the Proceedings of the National Academy of Sciences, unveils two new species of giant penguins from fossils unearthed in Peru's Atacama Desert.
The discovery pushes the date of penguin migration to equatorial regions back more than 30 million years, to one of the warmest periods of the last 65 million years.
The find also casts doubt on climate as the main factor in penguins' choice of habitat through history.
"The public is very familiar with the image of penguins and icebergs," Clarke said.
Today's penguins are cold-adapted and therefore at grave risk from global warming, she said, but the new fossils suggest that hasn't always been true.
(Clarke's research was funded by the National Geographic Society's Expeditions Council. National Geographic News is a division of the National Geographic Society.)
The new study describes two new species of penguins from fossils, including the first complete skull from an ancient giant penguin.
That species, which the authors say lived in Peru about 36 million years ago, is the third largest penguin known and stood about 4.5 feet (1.5 meters) tall.
The other, dating to 42 million years, was about three feet (a meter) tall, which is comparable to the today's second largest living penguin, the king penguin.
Most modern penguins in South America are 2 feet (0.6 meter) tall or less.
(See a penguins photo gallery.)
Clarke said it's counterintuitive that some of the biggest penguin fossils were found in the lower latitudes, closer to the Equator. The commonly accepted belief has it that larger animals live in colder conditions closer to the Poles.
The study also describes the first complete skull of a giant penguin, which provided a tantalizing glimpse into ancient penguin lifestyle.
Differences in the flipper also suggest variations in the animals' walking and swimming styles, compared with modern penguins, Clarke said.
The neck and skull of the ancient species were connected with different arrangements of muscle, and their beaks were a foot (0.3 meter) long.
"It doesn't scale," Clarke said of the beak. "It's really pointed, and there's this texturing on the bone, a horny sheath. My speculation is that they're eating fish, using some kind of spearfishing."
Cooler Than They Used to Be
Scientists had previously believed that penguins migrated to northern South America during a cold era between four and eight million years ago.
But the new fossils, which Clarke analyzed with colleagues in the U.S. and Peru, are from a warm period more than 30 million years earlier.
(Read related story: "World's Oldest Penguin Fossils Suggest Birds Outlived Dinos" [April 11, 2006].)
The finding counters another theory published last year suggesting that today's penguins diversified all over the Earth during a cooling period.
Ewan Fordyce, head of the geology department at the University of Otago, New Zealand, said the new results shed light on penguin "structure, history, and lifestyles during an interval that is not well sampled."
He believes the study opens a door for more studies of marine vertebrates and their responses to climate change.
"For so long," he said, "people have viewed evolution and extinction as driven by classical biological interactions, such as competition.
"With the rise of plate tectonic views of the Earth, we are rapidly gaining an appreciation of physical driving forces, such as climate change and change in ocean circulation."
In the case of the penguins, ocean circulation patterns may have been more influential than global temperature in allowing the giant historical birds to inhabit equatorial regions.
Clarke and her colleagues have proposed that cold-water upwelling off the Peruvian coast may have benefited the penguins, either by providing colder waters or by providing nutrient-rich waters with high amounts of food.
The authors stressed that while the giant penguins of yesteryear may have thrived in warmer climates, modern penguins are cold adapted and quite vulnerable to warming.
(See an interactive map of the effects of global warming.)
"What we think is important to recognize is that for a very large early part of their history, they didn't have that constraint [to colder climates]," Clarke said.
"Whatever ecologies and limitations we see in living species, it's important not to attribute those to every part of that species' history."
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