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Pleistocene megafauna is the set of large animals that lived on Earth during the Pleistocene epoch and went extinct during the Quaternary extinction event. Megafauna is a term used to describe an animal with an adult body weight of over 44 kg. ==Paleoecology== The last glacial period, commonly referred to as the 'Ice Age', spanned 125,000〔 to 14,500〔 years ago and was the most recent glacial period within the current ice age which occurred during the last years of the Pleistocene era.〔 The Ice Age reached its peak during the last glacial maximum, when ice sheets commenced advancing from 33,000 years BP and reached their maximum positions 26,500 years BP. Deglaciation commenced in the Northern Hemisphere approximately 19,000 years BP, and in Antarctica approximately 14,500 years BP which is consistent with evidence that this was the primary source for an abrupt rise in the sea level 14,500 years ago.〔 A vast Mammoth steppe stretched from Spain across Eurasia and over the Bering land bridge into Alaska and the Yukon where it was stopped by the Wisconsin glaciation. This land bridge existed because more of the planet's water was locked up in glaciation than now and therefore the sea-levels were lower. When the sea levels began to rise this bridge was inundated around 11,000 years BP. During the last glacial maximum, the continent of Europe was much colder and drier than it is today, with polar desert in the north and the remainder steppe or tundra. Forest and woodland was almost non-existent, except for isolated pockets in the mountain ranges of southern Europe.〔 The fossil evidence from many continents points to the extinction mainly of large animals at or near the end of the last glaciation. These animals have been termed Pleistocene megafauna. The most common definition of megafauna is an animal with an adult body weight of over 44 kg. Across Eurasia, the Straight-tusked elephant became extinct between 100,000–50,000 years BP. The hippopotamus, interglacial rhinoceros (''Stephanorhinus''), cave bear (''Ursus spelaeus''), and heavy-bodied Asian antelope (''Spirocerus'') died out between 50,000-16,000 years BP. The spotted hyena, woolly rhinoceros and mammoths died out between 16,000-11,500 years BP. The musk ox died out after 11,500 BP, as did the giant deer (''Megaloceros'') with the last pocket having survived until about 7,700 years BP in western Siberia. A pocket of mammoths survived on Wrangel Island until 4,500 years BP. As some species became extinct, so too did their predators. Among the top predators, the sabre-toothed cat (''Homotherium'') died out 28,000 years BP, the cave lion 11,900 years BP, and the leopard in Europe died out 27,000 years BP. The Late Pleistocene was characterized by a series of severe and rapid climate oscillations with regional temperature changes of up to 16 °C, which has been correlated with megafaunal extinctions. There is no evidence of megafaunal extinctions at the height of the LGM, indicating that increasing cold and glaciation were not factors. Multiple events appear to also involve the rapid replacement of one species by one within the same genus, or one population by another within the same species, across a broad area. Modern human's ancestors first appeared in East Africa 195,000 years ago. Some migrated out of Africa 60,000 years ago with one group reaching Central Asia 50,000 years ago.〔 From there they reached Europe, with human remains dated 43,000-45,000 years BP discovered in Italy, Britain, and in the European Russian Arctic 40,000 years ago.〔 Another group left Central Asia and reached the Yana River, Siberia, well above the Arctic circle 27,000 years ago. Modern humans then made their way across the Bering land bridge and into North America between 20,000-11,000 years ago, after the Wisconsin glaciation had retreated but before the Bering land bridge became inundated by the sea. These people then populated the Americas. In the Fertile crescent the first agriculture was developing 11,500 years ago.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Pleistocene megafauna」の詳細全文を読む スポンサード リンク
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