That's according to Travis Park, a PhD student at the Museum of Victoria and Monash University who has spent the past several years scouring the fossil record to reconstruct the long and complicated legacy of penguins in Australia. His results, published this week in the journal PLOS One, outline millions of years of colonization by at least half a dozen species of everyone's favorite flightless bird (sorry, emus).

"Australia is the missing piece of the puzzle of penguin evolution," Park said, noting that research on the Spheniscidae family is more sparse on the continent than elsewhere in the world. "I wanted to put Australia's penguins in their global context."

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The story starts during the Eocene, some 40 million years ago, when Australia and Antarctica were just beginning to drift apart. The still-narrow strip of ocean between them was easy for penguins to traverse, and at least two species colonized the newly isolated continent during this period.

Twenty million years later, those archaic penguins had come and gone, and a new bird was on the scene: Anthropodyptes gilli, the giant penguin. Carried by favorable ocean currents, they arrived from elsewhere, rather than evolving from the existing population.

These guys were nearly five feet tall — 50 percent bigger than the largest living penguin, the Emperor — and had long, spearlike beaks.

"They wouldn't have been the cute, feathered things we see today," Park said. "They were quite fearsome looking."

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Most giant penguins died out roughly 23 million years ago — probably because the rise of modern seals and dolphins meant they were out-competed for food. But the Australian crew was particularly tenacious. Isolated by the ever-increasing expanse of the Southern Ocean, they held on for another 3 million to 5 million years.

"They were the last of the giants," Park said.

The inexorable drifting of the Australian continent likely explains why it was colonized by birds on so many separate occasions. As continents shifted, so did ocean currents. Waters that once may have borne swimmers away from the continent reversed course to help carry them toward it, then switched to push them away again. After the disappearance of the giant penguins, there were two more waves of colonization — the last, by the tiny "fairy penguins," about a million years ago.

But there are still gaps in the record that need to be filled in, including a warming period 15 million years ago and a cooling period 12 million years after that.

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These are "chapters of the penguin story we want to know more about," Erich Fitzgerald, a senior paleontologist at the Museum of Victoria and co-author of the study, told the PLOS blog Paleo Community. "Australian fossils may be the key to understanding these millions of ‘missing years.' "