A recent expedition to Antarctica led to the discovery of a remarkable ancient forest. Approximately 260 million years old, this fossil forest provides evidence that the now ice-covered continent was once forested.

Antarctica is commonly associated with snow, ice and cold, but the continent was very different approximately 260 million years ago. Recent discoveries show that it was once covered by extensive forests.

During an expedition in 2016, researchers Erik Gulbranson and John Isbell made an unexpected discovery. While searching for fossils, they found fossilised fragments of the oldest forest identified to date in the southern polar region. Although its age has not yet been precisely established, they estimate that the forest is approximately 260 million years old.

The researchers identified 13 fossilised fragments of ancient trees. According to Erik Gulbranson, a professor at the University of Wisconsin–Milwaukee, “the entire continent was much warmer and more humid than it is today”. Instead of ice, the landscape supported dense forests with plants adapted to extreme polar temperature changes, comparable to the forests of present-day Siberia.

Like approximately 95% of all life on Earth, the Antarctic forest was affected by the end-Permian mass extinction. Greenhouse warming associated with volcanic eruptions led to the loss of more than 90% of marine species, 70% of terrestrial animal species and many plants. The fossilised remains found in Antarctica, buried beneath volcanic ash, preserve biological and chemical characteristics of the ancient trees. They provide a rare opportunity to investigate this ecosystem.

Before the end-Permian extinction, forests in the southern polar region were dominated by a tree species in the genus Glossopteris, according to Gulbranson’s account to Live Science. These large trees reached 20–40 metres in height and had broad leaves larger than a human forearm. Gulbranson explains that the forests did not disappear entirely after the end-Permian catastrophe; instead, their composition changed. Although Glossopteris did not survive, other tree species took its place, including some related to modern ginkgo trees.

Study of the fossilised specimens may clarify how Antarctic vegetation changed and what caused those changes. The specimens can also reveal how these plants were adapted to the southern polar climate, offering insight into an ecosystem that has long since disappeared.

Sources: National Geographic, Live Science