Camels... the ships of the Arctic?
That's the theory put forward on Tuesday by Canadian palaeobiologists, who point to evidence that giant camels roamed the High Arctic millions of years ago, when that region was relatively balmy and forested.
The proof comes from a fossilised and fragmented limb bone found alongside fossilised trees in Ellesmere Island in Nunavut province.
Barren today, Ellesmere lies alongside the northwestern tip of Greenland at a latitude of around 80 degrees north.
The age of the fossils is indicated by the soil deposits, which are around 3.5 million years old, and the camelid origins come from proteins in the collagen, the main protein in mammal bones, the study says.
"The Ellesmere camel is the most northerly evidence of camel," the paper says.
"It inhabited the High Arctic during the mid-Pliocene warm period when the area was forested and the broad channels of the western Canadian Arctic archipelago were filled with sediment."
Global temperatures then were around two or three degrees Celsius (3.5-5.0 degrees Fahrenheit) warmer than today.
The Strathcona Fiord area where the find was made probably had a year-round average temperature that was "slightly below freezing," and had a larch forest, despite nearly six months of 24-hour darkness.
The findings boost contentions that the granddaddy of all camels came not from the Sahara, the Gulf or Asia, but from North America, say the study authors.
Early camels migrated across to Asia via what was then a narrow land bridge across the Bering Strait, the paper suggests.
"The family Camelidae originated in North America during the Eocene period about 45 million years ago," it says.
During the Miocene period, from around 23 million to five million years ago, the family diversified.
By the end of the Miocene, two strains dominated: the ancestors of today's camels, which had reached Eurasia, and the forerunners of llamas and alpacas, which had reached South America.
Until now, the most northerly-found camel came from a giant fossil found at Old Crow Basin, at latitude 67 degrees north, in Canada's Yukon.
The study, led by Natalia Rybczynski of the Canadian Museum of Nature in Ottawa, appears in the journal Nature Communications.