Around 53 million years ago the Arctic Circle's freezing, windswept Ellesmere Island would have been unrecognizable. Damp, humid and lush, the place would have been covered by thick cypress swamps not unlike what still survives in southern Louisiana. Swinging through the trees would have been primates, while alligators patrolled the waterways and tapirs grazed on the land. In among all this, new research shows that a giant, flightless bird stalked the wetlands searching for food.
Researchers were able to confirm this based on a single toe bone that has been identified as belonging to a monstrous bird known as Gastornis. Fossils from the beast have been found across Europe and China, as well as mainland United States, but this is the farthest north it is now known to have lived. In fact, like today Ellesmere Island would have spent the half the year in total darkness, and the researchers speculate that perhaps ithe bird migrated south following the Sun. The paper, published in Scientific Reports, also describes another species of bird living at the same time, which looked like a cross between a duck and a flamingo. 
The toe bone was discovered in the 1970s but remained undescribed until now. Comparing it with known fossils of Gastornis found in Wyoming, the researchers were able to confirm that the specimen did indeed belong to the same giant bird species living much farther south during the same period. There have also been reports that at the time the toe bone was found, fossil foot prints from a large flightless bird were also discovered, but unfortunately the exact location of these was not recorded. It’s possible that these also belonged to Gastornis.
The giant bird was a formidable beast. Standing 1.8 meters (6 feet) tall, its head and beak were incredibly heavily built and would have been similar in size to a horse’s head. The reason for its powerful beak has been debated, with some suggesting that it would have been a fearsome predator, chasing down and hunting the tiny ancestors of the modern horse. But the heavy, stout nature of its legs seem to imply that it was actually quite slow moving, which led others to conclude that it may have been an ambush predator instead.
Yet recent work throws all that into doubt. After studying some newly discovered tracks in Washington, thought to be created by Gastornis 50 million years ago, researchers showed that the massive birds lacked raptor-like claws on their feet. This backs up the idea that rather than being predators or scavengers, they were instead mainly herbivores. This is also supported by the lack of a hook on their beaks, which is normally seen in meat-eating raptors. Perhaps the massively powerful beaks were instead an adaptation to cracking tough nuts and seeds, and plucking up hardy plants.
The researchers hope that understanding the past ecosystems of a warm Arctic might help us know how the region will change as the ice melts and planet continues to heat up due to climate change.
Image in text: Full skeleton of the extic bird on display from Wyoming. Vince Smith/Wikimedia
