for National Geographic News
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.
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