National Geographic : 2009 May
drier, cloud cover was limited, and strong winds swept the electric blue skies. In place of tundra grew a vast, arid grassland that paleobiologist R. Dale Guthrie has called the mammoth steppe, stretching from Ireland to Kamchatka and across the Bering land bridge to Alaska, the Yukon, and much of North America. e grasses, broad-leaved herbs, and low shrubs of the steppe provided nutritious food, and in addition to mammoths, nourished a profusion of other outsize, exuberantly hairy mammalian megafauna---woolly rhinoceroses, enormous long-horned bison, and bear-size beavers, as well as the fearsome carnivores that hunted them: saber-toothed cats, cave hyenas, and giant short-faced bears. en, between 14,000 and 10,000 years ago, the mammoths disappeared from most of their range, along with most of the other large mammal species in the Northern Hemisphere---as many as 70 percent in some regions. These extinc- tions were so sweeping that scientists have evoked a number of cataclysmic events to explain them---a meteorite strike, killer fires and droughts, and a virulent, cross-species hyperdisease. Since the extinctions coincided with the end of the most recent ice age, how- ever, many researchers believe that the primary cause of the great die-o was the sharp rise in temperature, which dramatically altered the vegetation. A recent computer simulation of landscape changes during the late Pleistocene suggests that 90 percent of the mammoth s for- mer habitat disappeared. "We have strong evi- dence that climate change played a signi cant part in their extinction," says Adrian Lister, a paleontologist and mammoth expert at the Nat- ural History Museum in London. "In Eurasia, Reindeer herder Yuri Khudi (at le ) and sons found the carcass in Siberia s Yamal Peninsula in May 2007 and alerted local authorities. Mammoth remains commonly turn up in the region but o en are sold to fossil dealers before scientists can examine them. In gratitude, o cials named the calf Lyuba, a er Khudi s wife.