June 11, 2009 -- The creatures that roamed the balmy swamps and forests of the prehistoric Canadian high Arctic survived the long dark season by switching diets dramatically, according to a new study.
Instead of migrating south or hibernating for the winter like most animals today, they endured, foraging in dormant forests through the long polar gloaming.
Today Canada's Ellesmere Island is a frigid tundra. But 53 million years ago it resembled a Louisiana bayou, teeming with plants and crowded with alligators, turtles, and tapirs. Even lemur-like creatures swung from the trees.
Scientists have long wondered how the animals survived the long winter. Though temperatures didn't often get below freezing, plants must have gone into hibernation during the six months of darkness.
New evidence extracted from the teeth of the hippopotamus-like Coryphodon suggests they subsisted on leaf litter, decaying fruits and twigs through the winter. Jaelyn Eberle of the University of Colorado in Boulder and a team of researchers sampled carbon isotopes from the teeth of nine Coryphodons, three tapirs and two rhinoceros-like brontotheres, all of which lived on ancient Ellesmere.
Related Content:
The results show the plant-eaters lived off of abundant flowering plants, leaves, and greenery in the spring and summer months. But in the winter they switched to eating dead and dying plant matter and fungi.
"People first discovered alligators in the high Arctic in 1975, and I've been going up there since the 1990's," Eberle said. "But we never thought to stop and ask 'why?' or 'how?' How were these animals able to survive up there -- what made them special?"
Eberle speculates the land-bound creatures evolved a unique digestive system. Dead plant matter is mostly low in nutritional value, so the animals must have compensated each winter by eating huge amounts of food, and thoroughly digesting it.
"In a way this is a case of truth being stranger than fiction. We don't have an ecosystem like this extinct ecosystem. It's amazing how resistant to changes in light these animals can be," Christopher Beard of the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania said.
Of Eberle's theory he added: "It's a persuasive, interesting hypothesis," though he stressed that it's still far from certain.
As human-induced global warming invades the Arctic in coming years, Eberle expects animals will again move north into the thawing Arctic wastes. But she says it's unlikely alligators or hippos will soon return; the early Eocone climate of Ellesmere was drastically warmer than present day, averaging temperatures 25 degrees centigrade higher back then.
Related Links:
Discovery News blog: Earth Pub
How Stuff Works: The Arctic Circle
our sites
video
mobile
shop
stay connected
corporate
