Sitting on the southernmost point of Earth and almost completely covered in ice, Antarctica is one of the great human mysteries to this day. Because of the conditions on Antarctica, it’s difficult to perform a lot of research on the continent. The average temperature is nearly 60 degrees below zero (fahrenheit), and with a terrain of ice it’s hard to set up camp anywhere.

Not deterred, though, scientists like John Isbell and Erik Gulbranson were able to brave the elements and start an expedition during Antarctica’s summer. During this time, the sun never sets, making it a little bit warmer, but still unbearably cold. Isbell, Gulbranson and their team spent several months searching for fossils in Antarctica, looking for clues of the past. What they found was a key to what Antarctica used to look like.

The team recovered more than a dozen fossil fragments, and it wasn’t from animals, but actually from trees. The trees were found to be more than 250 million years old, happening before the largest mass extinction in Earth’s history. The findings suggest that Antarctica’s climate was much more humid at one point and able to contain vegetation. The trees that were found could grow from anywhere between 65 and 130 feet tall, and Gulbranson says the leaves (which were flat) were the size of a person’s arm.

A fossil find like the one in Antarctica is incredibly rare, Gulbranson says. “They’re actually some of the best-preserved fossil plants in the world. The fungi in the wood itself were probably mineralized and turned into stone within a matter of weeks, in some cases probably while the tree was still alive. These things happened incredibly rapidly. You could have witnessed it firsthand if you were there.”

“The continent as a whole was much warmer and more humid than it currently is today,” Gulbranson said. “Oddly enough, these field sites would have actually been very close to what their current latitude is.” It’s possible that the region also had ferns, moss and other plants that could have been able to handle 24 hours of both daylight and sunlight, as well as frigid conditions.

“These trees could turn their growing cycles on and off like a light switch,” Gulbranson said. “We know the winter shutoff happened right away, but we don’t know how active they were during the summertime and if they could force themselves into dormancy while it was still light out.”

The team looked at the rings on the trees, which are typically used to determine age. They found that the summer activity was fast, and was able to stop growing once the harsher conditions and perpetual darkness kicked in, taking only a month. Plants these days can take several months to do the same.

The forests of Antarctica weren’t able to survive the mass extinction that was believed to be caused by a series of volcanic eruptions that caused a rise in CO2 in the atmosphere. This produced mass freezing where nearly all life was lost, including the forests.

“This forest is a glimpse of life before the extinction,” Gulbranson said. “Which can help us understand what caused the event…This plant group must have been capable of surviving and thriving in a variety of environments.”

He added that “It’s extremely rare, even today, for a group to appear across nearly an entire hemisphere of the globe.” Now, Gulbranson and his team are using the fossils to see how vegetation responds to massive increases in atmospheric CO2.

“The geologic record shows us the beginning, middle and end of climate change events,” he said. “With further study, we can better understand how greenhouse gases and climate change affect life on Earth.” It won’t be easy to continue research in Antarctica, though, as Gulbranson says “It’s certainly still a raw and challenging place to try to be as a human being.” Not many people have been willing to face the conditions. “Most of Antarctica is still unexplored. Sometimes, you might be the first person to ever climb a particular mountain.”