Gastornis was a flightless bird that lived in the Arctic 50 million years ago, and the ancient avian has now been described in new details from fossil remains examined by investigators. Paleontologists once believed the creature was a fearsome predator, hunting prey on Ellesmere Island, off the coast of Greenland.

University of Colorado researchers now suggest the species, which weighed several hundred pounds, was likely a herbivore. The creatures likely consumed fruits, nuts, plants, and seeds, the new study reveals.

In the modern area, temperatures in this part of the Arctic can drop to 40 degrees below zero Fahrenheit in the depths of winter. During the Eocene Epoch, however, the region was significantly warmer than it is today.

Accompanying Gastornis in the area were mammals much like rhinos and hippos, as well as alligators, turtles, tapirs, and a variety of primates. The region at the time was similar to the current climate seen in the southeastern regions of the United States.

The fossil used in the study, a toe bone, was discovered in the 1970s. This is the first time the artifact has been studied in great detail. Gastornis stood around 6 feet tall, and weighed several hundred pounds, roughly the same as a large human male.

Presbyornis, another local species from the same era, was also described in a paper accompanying the new research. Biologists describe the creatures as looking similar to a swan or goose, but sporting long legs, much like a flamingo. Unlike Gastornis, however, Presbyornis could fly.

Despite the temperate climate of the time, the region was still subject to months of darkness every year, so researchers are uncertain whether Presbyornis lived in the area year-round, or migrated seasonally.

"There are some sea ducks today that spend the winter in the cold, freezing Arctic, and we see many more species of waterfowl that are only in the Arctic during the relatively warmer spring and summer months," said Thomas Stidham of the Chinese Academy of Sciences.

Analysis of life forms from the distant past, when the Arctic was warmer, could provide biologists with insight into how the biosphere could be affected by global warming.

Study of birds who lived on Ellesmere Island in the Eocene Epoch was published in the journal Scientific Reports.