Argentinian archaeologists have unearthed fossils revealing that Antarctica was once home to Colossus penguins that weighed up to 250 pounds and stood as tall as 6 feet 7 inches, the largest species ever to waddle the earth.

Carolina Acosta Hospitaleche, of La Plata Museum in Argentina, shared her research with New Scientist magazine, explaining that 37 million to 40 million years ago was “a wonderful time for penguins, when 10 to 14 species lived together along the Antarctic coast.” The bones in question were found earlier this year on Seymour Island (the chain of islands closest to the southern tip of South America) and suggest that the bird stood two meters high from the tip of its beak to its toes, twice the size of the Emperor penguins that currently rule the frozen region.

“What they have in particular and which is striking is the size, because even though we already knew that there were giant penguins in Antarctica, these bones are really much larger than any other bones we knew of from penguin fossils,” Hospitaleche said, as quoted by South Africa’s News 24. “They’re not the only penguins that lived between 34 and 37 million years ago, which is the age of these remains, but we also know that between 10 to 14 species, depending on differing opinions, existed on the shores of Antarctica.”

Perhaps not surprisingly, the larger a penguin is, the deeper it can dive. The Colossus penguin, officially known as the Palaeeudyptes klekowski, is believed to have been able to stay underwater hunting fish for 40 minutes at a time. The massive birds would have also enjoyed much warmer weather than Antarctica currently experiences, with temperatures closer to what modern-day South America, Tierra del Fuego in particular, has grown accustomed to.

Colossus penguins likely died out in the midst of the Eocene period (55.8 to 33.9 million years ago), a widely defined period that is marked by the appearance of early horses, deer, cattle, sheep and rhinoceroses. Such a time would be almost completely unrecognizable to humans living today, with crocodiles swimming through the Arctic, pine trees in the Antarctic, and palm trees throughout what are now the Midwestern states.