(CNN) -- Picture this: A giant penguin with a long, peculiar beak, lounging in the warm sun.

The giant penguin Icadyptes salasi, right, and Perudyptes devriesi, left, are shown with a modern penguin.

It could be a promotion for the next animated Hollywood movie.

But this big bird is the real thing, its recently discovered fossils providing researchers with several scientific oddities. Not only are the birds extra large by modern standards, they thrived in one of the warmest periods in the past 65 million years.

"We have this ingrained notion of a penguin on an iceberg in a cool sea. But for most of their long history, penguins were in situations of no ice, with maybe crocodiles near them," said Julia Clarke, assistant professor of marine, earth and atmospheric sciences at North Carolina State University in Raleigh, North Carolina.

Clarke, who studies the biodiversity of living birds, and colleagues in Peru and Argentina have described two species of extinct penguins that lived tens of millions of years ago. It was during a time when Earth was a lot warmer than it is today. The fossils were found in Peru in 2005.

The larger of the two new species, Icadyptes salasi, lived about 36 million years ago on the southern coast of Peru. The skull that was discovered includes an intriguing beak that is almost a foot long.

"The texturing on the bone of the beak is unlike any living penguin," said Clarke.

The bird likely had more developed jaw muscles than current penguins, and probably ate large prey, including fish.

The climate of the earth at that time was far different from the icy polar regions and the toastier, tropical middle section we inhabit today.

"The global average temperature was much higher than at present," said Clarke. "And there was relatively little difference between the temperatures at the poles and the equator," she said.

The Earth's first polar icecaps developed about 34 million years ago, after these two penguin species became extinct.

The other newly discovered species, Perudyptes devriesi, is even older, inhabiting the planet 42 million years ago. It resembled one of the largest contemporary penguin species, the King penguin, standing two and a half to three feet tall. Its fossils show that its wings may have looked a little different from the very specialized "paddles" that the wings have become today.

Clarke emphasized that because some penguins on the lower branches of the birds' family tree lived well in warmer temperatures, it would be a colossal mistake to believe that penguins now living could simply adapt to the changes brought about by global warming.

"What happened over millions and millions of years cannot usefully inform us about what may happen over just the next 1,000 years," she said. "The data from these new fossil species cannot be used to argue that warming wouldn't negatively impact living penguins."

These penguin fossils may change understanding of just how and where these flightless birds evolved. Until now, researchers theorized that penguins evolved in high latitudes in New Zealand and Antarctica, eventually moving to warmer areas nearer the equator about ten million years ago. That would have been 24 million years after the transition from very warm temperatures in the Paleocene and Eocene eras to major planetary cooling and the appearance of permanent North and South Poles.

So what does a vertebrate paleontologist think about all the attention penguins are now getting with pop culture hits like "March of the Penguins" and "Happy Feet"?

"Anytime people are motivated to engage and become emotionally connected to the natural world is a good thing for conservation concerns," said Clarke.

The research is published in Proceedings of the National Academy of Sciences. It was funded by the National Geographic Society, and the National Science Foundation Office of International Science and Engineering. E-mail to a friend

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