Carl Zimmer writes: The 57 million-year-old fossil is both fearsome and comical: a long-beaked penguin that stood 5 feet 7 inches tall and weighed about 220 pounds.

“It was as tall as a medium-sized man,” said Gerald Mayr, a paleontologist at the Senckenberg Research Institute in Frankfurt, Germany, and lead author of a report in Nature Communications on Tuesday announcing the discovery.

By comparison, the tallest living species, the emperor penguin, reaches about four feet in height. Kumimanu biceae, as the fossil was named, would have towered above the emperor, and above just about all other known ancient penguins.

(In 2014, another team of researchers estimated that a 34-million-year-old species stood six feet tall, but they based that estimate only on two bone fragments.)

Kumimanu wasn’t just exceptionally big; it also ranks among the oldest penguin fossils yet found. Both its age and its size make Kumimanu important to understanding the astonishing transformation that turned a lineage of flying birds into flightless swimmers.

The 18 modern species of penguin, ranging from the coast of Antarctica to the Galápagos Islands at the Equator, are impressively adapted to aquatic life. Rigid, blade-shaped wings enable them to shoot through the water at up to 22 miles an hour. Record-setting human swimmers don’t even reach six m.p.h.

But their adaptations to water have also left them unable to fly. When penguins haul out to rest or rear their young, they can only waddle about on stumpy legs. “They’re so unbirdlike that many people would not know they are birds,” Dr. Mayr said.

While penguins may look profoundly different from other birds, their DNA points to a close kinship to such species as albatrosses and petrels. These birds all fly over water to hunt for prey, hinting that the ancestors of penguins may have, too. [Continue reading…]