A new paper published in the journal Scientific Reports describes the first and only fossil evidence from the High Arctic of the giant, flightless bird Gastornis.
Gastornis lived on Ellesmere Island in the High Arctic about 53 million years ago. Image credit: Marlin Peterson.
The evidence is a fossil toe bone from Ellesmere Island above the Arctic Circle.
“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 lead author Prof. Thomas Stidham, of the Chinese Academy of Sciences’ Institute of Vertebrate Paleontology and Paleoanthropology.
“But this is the first time the bone has been closely examined and described.”
Gastornis — a large middle Eocene (55-36 million years ago) bird — probably was a vegan, using its huge beak to tear at foliage, nuts, seeds and hard fruit.
“The fossil specimens of Gastornis also have been found in Europe and Asia,” Prof. Stidham said.
“We knew there were a few bird fossils from Ellesmere Island, but we also knew they were extremely rare,” added co-author Dr. Jaelyn Eberle, of the University of Colorado at Boulder.
“In addition to the Gastornis bone from Ellesmere, another scientist reported seeing a fossil footprint there, probably from a large flightless bird, although its specific location remains unknown.”
She added: “about 53 million years ago during the early Eocene Epoch, the environment of Ellesmere Island was probably similar to cypress swamps in the southeast U.S. today.”
“Fossil evidence indicates the island, which is adjacent to Greenland, hosted turtles, alligators, primates, tapirs and even large hippo-like and rhino-like mammals.”
According to the paleontologists, Gastornis, along with some of the mammalian and reptilian members of the Eocene Arctic fauna, likely over-wintered in the Arctic.
“Multiple paleoclimate proxies estimate a mild temperate climate for the Eocene High Arctic, where winters remained at or just above freezing and summer temperatures extended to 20 degrees Celsius or higher,” Prof. Stidham and Dr. Eberle wrote in the Scientific Reports paper.
“These temperatures are a far cry from today’s High Arctic, where central Ellesmere Island experiences a mean annual temperature of minus 19 degrees Celsius, a warm month mean temperature of about 6 degrees Celsius and a cold month mean temperature of minus 38 degrees Celsius or colder.”
“Despite the milder Eocene climate on Ellesmere Island, prolonged periods of darkness occurred during the winter.”
In the same paper, the scientists described another Ellesmere Island bird from the early Eocene. 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 team that found the Gastornis bone.
“It is not known whether Presbyornis migrated north to Ellesmere Island every year or lived there year-round,” Prof. Stidham said.
“Given the fossils we have, both hypotheses are possible. 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.”
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Stidham, T.A. & Eberle, J.J. 2016. The palaeobiology of high latitude birds from the early Eocene greenhouse of Ellesmere Island, Arctic Canada. Sci. Rep. 6, 20912; doi: 10.1038/srep20912
