What Did Antarctica Look Like Before It Was Frozen?

When British explorer Robert Falcon Scott trekked through Antarctica, he encountered a frigid, inhospitable landscape covered by ice up to 3 miles thick, with temperatures as low as minus 133 degrees Fahrenheit. “Great God!” Scott wrote in his diary upon reaching the South Pole in January 1912, only to realize that his rival, Roald Amundsen, had beaten him there. “This is an awful place and terrible enough for us to have labored to it without the reward of priority.”

Suffering from exhaustion, frostbite and malnourishment, Scott and his four crewmates all died on the return journey—but not before they discovered fossilized leaves in a glacial moraine. The tantalizing clue suggested that the frozen continent had not always been so frozen. In fact, as scientists have since learned, temperate rainforests and even palms once covered parts of Antarctica, providing habitat for dinosaurs and a plethora of other creatures.

“We know it was clearly quite warm,” says Guy Paxman, a polar geophysicist at Durham University in the United Kingdom who studies the Earth’s ice sheets. “There must have been a time when Antarctica didn’t even experience much in the way of frost in the winter.”

For hundreds of millions of years, Antarctica was connected to South America, Africa, India, Madagascar and Australia as part of the supercontinent Gondwana. Then, roughly 180 million years ago, Gondwana began splitting apart, with India and Madagascar likely breaking off first, followed by Africa, South America and finally Australia.

The other continents drifted north, while Antarctica settled over the South Pole. “Antarctica was in more or less the same place it is now during the age of dinosaurs,” says Matt Lamanna, a paleontologist at the Carnegie Museum of Natural History in Pittsburgh who has collected dinosaur fossils on all seven continents. “It hasn’t moved very much since then.”

Lamanna points out that vestiges of Gondwana remain visible, most obviously in the way South America’s eastern bulge appears to fit like a puzzle piece into Africa. Using more modern techniques, a 2021 study uncovered a magnetic link between Antarctica and its former neighbors.

Scientists have looked at the geological and fossil records, showing that, if you go back far enough, the former landmasses of Gondwana share many of the same rocks, flora and fauna. For example, Antarctic fossils have been found of southern beech trees, which currently live as far apart as Patagonia and Tasmania.

During their doomed expedition, Robert Falcon Scott and his crewmates understood the scientific importance of the fossils they had collected. Though dropping weight might have helped them move faster toward safety, they apparently refused to jettison the fossils, which were later found alongside their dead bodies.

Because it’s so cold and remote, with over 99 percent of its area covered year-round in ice and snow, Antarctica has the worst fossil record of any continent, Lamanna explains. A 2018 study asserts that “the subglacial landscape of Antarctica is less well known than that of the moon and Mars.”

Nonetheless, since Scott’s death, scientists have uncovered fossilized evidence of a host of ancient Antarctic plants, including conifers, gingkos, ferns, liverworts and mosses. Pollen and spores have also been found belonging to palm trees and other subtropical species.

“It is one of the coolest things that you can ever experience, sitting on an ice- and snow-covered mountainside in Antarctica breaking open rocks and finding leaves that look like something you’d see in a forest here in Pennsylvania,” says Lamanna, who has been to Antarctica three times, most recently in 2016. He says a particularly “mind-blowing” moment was finding helicopter seeds resembling those from a modern maple.

The first Antarctic dinosaur fossil was unearthed in 1986. Scientists now know of two Antarctic dinosaurs from the Jurassic Period: Cryolophosaurus and Glacialisaurus. Cryolophosaurus, meaning “frozen crested lizard,” sported an Elvis-like pompadour and may have preyed on Glacialisaurus, a long-necked plant-eater, Lamanna says.

Known Antarctic dinosaurs from the Cretaceous Period include semi-bipedal ornithopods, a titanosaur, an ankylosaur, a duck-billed dinosaur and a bird-like predator called Imperobator. Lamanna says the duck-billed dinosaur, or hadrosaur, is known from a single tooth. “Hadrosaur teeth are so distinctive,” he says. “They can be confused for nothing else.”

Despite its position over the South Pole, summer temperatures on Antarctica may have averaged nearly 70 degrees Fahrenheit during the mid-to late Cretaceous, when temperatures spiked to record levels worldwide. “It’s the real peak of the warmth,” Paxman says, pointing out that volcanic activity and other natural causes pushed carbon dioxide levels in the atmosphere to roughly 1,000 parts per million.

By contrast, pre-Industrial Revolution carbon dioxide levels stood at around 280 parts per million. (As humans have burned fossil fuels, that level has since increased to more than 420 parts per million.)

“Antarctica during the Cretaceous must have been an environment with no modern analog,” Lamanna says. “It would have been a really interesting, almost alien ecosystem.”

Paxman imagines it would have somewhat resembled today’s Arctic, with certain species migrating poleward each summer to take advantage of the plentiful sunlight and then retreating to lower latitudes during the dark winter.

Well after the extinction of the dinosaurs, Antarctica’s weather cooled and subtropical plants disappeared. For a while, warmer ocean currents still reached Antarctic waters and glaciers were restricted to Antarctica’s mountains. But a big shift occurred around 34 million years ago, by which point Gondwana had long since split apart and carbon dioxide levels had fallen.

The Antarctic Circumpolar Current formed in the open seaways now separating Antarctica from South America and Australia, locking in frigid air and water. “There are very good records showing that the amount of ice in Antarctica rose significantly at that time,” Paxman says.

Even then, at least some hardy plants and animals held on. But roughly 15 million years ago, air and sea temperatures fell further, precipitation declined as well, and the ice sheet grew to its maximum extent. “That’s ultimately the final step where the vegetation really disappears, because it’s not only cold, it’s also dry and windy,” Paxman says.

Though marine life remains abundant around Antarctica, on land it’s another matter. Today, Antarctica’s largest fully terrestrial animal is a 0.2-inch-long midge. There are no trees or shrubs, and only two species of native flowering plants.

As human-caused climate change shrinks the ice sheet, more plants could possibly establish themselves on the frozen continent’s edges, Paxman says. Meanwhile, penguin and krill populations are dropping and sea levels are rising.