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This mother bear's experience gives her family a good chance of survival until spring arrives. They will return again and again as the thaw releases more fish. On the warmer plains and valleys that surround the plateau, grazers are on the move. They
自然百科2012年
This is Alaska today, a wetland of forests, boggy tundra, lakes and rivers rivers that still churn out fresh clues to the Ice Age past. This is a brick-sized tooth, and it belong to a woolly mammoth. Its narrow ridges of enamel tell us more about how
探索与发现2012年
Musk oxen and arctic hares are well-insulated against the cold as are the largest grazers of them all, the woolly mammoths. This herd is regrouping, ready for a long day feeding on the grasses beneath the snow. Mothers need to keep milk flowing for t
探索与发现2012年
But there is a problem with the idea that hunting caused the mass extinction. Mammoths were not the only animals to disappear. Camels survived for millions of years in North America, but disappeared around the same time as the mammoths. Wild horses f
探索与发现2013年