Students of historical geology will tell you that the life on Earth used to look drastically different than it does today. As more fossils are uncovered, scientists gain a clearer picture of the different kinds of animals and plants that used to dominate the planet.

According to a report from CBS News, a team of researchers from the Chinese Academy of Sciences in Beijing and the University of Colorado-Boulder have discovered the first fossil evidence of a 6-foot flightless bird that roamed the Arctic nearly 53 million years ago.

The fossil belongs to Gastornis, a massive vegan bird that had a head the size of a horse’s and weighed hundreds of pounds. Scientists believe that the climate in the Arctic was much different during the Eocene Epoch than it is today. Ellesmere Island, currently covered in ice, looked more like cyprus swamplands filled with turtles, gators, and other temperate creatures.

The fossil discovered on Ellesmere Island is nearly identical to one that was found in Wyoming, and both are confirmed to have been from the same time period. Researchers have discovered similar fossils in Europe and Asia, but this is the first time a Gastornis fossil was discovered in the Arctic.

“We knew there were a few bird fossils from up there, but we also knew they were extremely rare,” revealed study author and associate professor in geological sciences at CU-Boulder, Jaelyn Eberle. Eberle confirmed that a different scientist had found a similar fossil footprint on the Island, but its exact location remains unclear.

Eberle and her co-authors, including study lead Professor Thomas Stidham from the Chinese Academy of Sciences, Beijing, believe that the bird was a vegan, feeding on leaves, fruits, seeds and nuts. The paper also described a similar Eocene bird found on the same island, known as Presbyornis.

Presbyornis looked somewhat like a modern duck or goose, but had long crane-like legs. Scientists discovered an upper wing bone in the same dig as the 1970’s Gastornis toe bone.

Researchers compared the bones uncovered from the two sites and confirmed that they were from the same two species. This indicates that these ancient birds had a massive range, and migrated considerable distances. The two sites in Wyoming and Ellesmere Island are more than 4,000 kilometers apart.

It’s unclear if these massive birds spent the entire year in the Arctic, or only came seasonally. Even though the summers in the Arctic offered a long growing period during the Eocene, the winters were still likely cold and icy like they are today. The tilt of the Earth meant that Arctic winters only received a short window of sunlight, causing the land to freeze over.

There are currently a few ducks that winter on Ellesmere Island, where the temperatures can dip below negative 40 degrees Fahrenheit in the winter months.

“Permanent Arctic Ice, which has been around for millennia, is on track to disappear. I’m not suggesting that there will be a return of alligators or giant tortoises to Ellesmere Island anytime soon,” said Eberle. “But what we know about pas warm intervals in the Arctic can give us a much better idea about what to expect in terms of changing plant and animal populations there in the future.”