"It was still formidable but it was the plants that had to be fearful," 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.
And unlike modern day ducks and geese that migrate through the Arctic, Eberle said Gastornis was most likely a year-around resident. It would have had enough to plant material eat, she said, and probably wouldn't had the energy to migrate elsewhere.
"We would hyphosize that a large bird, just like large mammals up there, could overwinter in the Arctic," she said. "Because this is a land dwelling bird, I think they were permanent residents. Part of it is because – this is the same argument we use for the mammmals up there - it's energetically expensive for an animal that walks on land to travel from Ellesmere Island down the tree line each year."
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