Giant, flightless bird wandered the Arctic 50 mn years ago

A giant, flightless bird with a head the size of a horse, wandered about in the winter twilight of the high Arctic some 53 million years ago, scientists have revealed.

The confirmation came after researchers from the Chinese Academy of Sciences in Beijing and University of Colorado, Boulder, analysed the first and only fossil evidence from the Arctic of a massive bird known as Gastornis.

The evidence is a single fossil toe bone of the six-foot tall, several-hundred-pound bird from Ellesmere Island above the Arctic Circle.

The bone is nearly a dead ringer to fossil toe bones from the huge bird discovered in Wyoming and which date to roughly the same time.

"The Gastornis fossil from Ellesmere Island has been discussed by paleontologists since it was collected in the 1970s and appears on a few lists of the prehistoric fauna there," said professor Thomas Stidham from Chinese Academy of Sciences in Beijing.

But this is the first time the bone has been closely examined and described. Gastornis fossils also have been found in Europe and Asia.

"We knew there were a few bird fossils from up there, but we also knew they were extremely rare," added associate professor of geological sciences Jaelyn Eberle from CU-Boulder.

A paper by Stidham and Eberle appeared in Scientific Reports, an open access journal from the publishers of Nature.

"About 53 three million years ago during the early Eocene Epoch, the environment of Ellesmere Island was probably similar to cypress swamps in the southeast US today," Eberle said.

Fossil evidence indicates the island, which is adjacent to Greenland, hosted turtles, alligators, primates, tapirs and even large hippo-like and rhino-like mammals. Today, Ellesmere Island is one of the coldest, driest environments on Earth.

Originally thought to be a fearsome carnivore, recent research indicates Gastornis probably was a vegan, using its huge beak to tear at foliage, nuts, seeds and hard fruit.

A second Ellesmere Island bird from the early Eocene also is described by Stidham and Eberle in the new paper.

Named Presbyornis, it was similar to birds in today's duck, goose and swan family but with long, flamingo-like legs. The evidence was a single humerus, or upper wing bone, collected by the same paleontology team that found the Gastornis bone.

"Like Gastornis, Presbyornis was mentioned in several lists of Ellesmere Island fauna over the years but the bone had never been described," Stidham noted.

The new study has implications for the rapidly warming Arctic climate, primarily a result of greenhouse gases being pumped into Earth's atmosphere by humans.

"What we know about past 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," the authors noted.