February 2, 2009

Tropical turtle fossil found in Arctic

U.S. geologists say they have found the fossil of a tropical, freshwater Asian turtle in Arctic Canada.

The researchers from the University of Rochester in New York said their discovery suggests animals migrated from Asia to North America not around Alaska, as once thought, but directly across a freshwater sea floating atop the warm, salty Arctic Ocean.

Professor John Tarduno, who led the researchers, said the finding also suggests a rapid influx of carbon dioxide some 90 million years ago was the likely cause of a super-greenhouse effect that created extraordinary polar heat.

We've known there's been an interchange of animals between Asia and North America in the late Cretaceous period, but this is the first example we have of a fossil in the high arctic region showing how this migration may have taken place, said Tarduno. We're talking about extremely warm, ice-free conditions in the Arctic region, allowing migrations across the pole.

The research that included Donald Brinkman of the Royal Tyrrell Museum of Canada is reported in the journal Geology.