The Cretaceous-Tertiary Extinction event, which included the extinction of the dinosaurs, is probably the most famous of all the mass extinctions the earth has seen. The end of the Pleistocene Epoch (1.8 million years to about 10,000 years ago), however, also witnessed the extinction of many animals. This mass extinction is often referred to as "the Ice Age". We must remember that the Earth has seen many periods of glaciation (or Ice Ages); this is merely the most famous one.
It has been proposed that the reason so many large mammals died out at the end of the Pleistocene was due to a sudden change in the global climate which caught the animals unawares, and they were not able to adapt quickly to the cold. This does not explain why so many animals that were adapted to life in cold climates went extinct while others survived. The woolly rhinoceros, woolly mammoth and cave bear were all accustomed to living in cold climates. Mastodons, glyptodonts, dire wolves, ground sloths, sabre-toothed cats and giant bison would have all been able to migrate further south. Also, why did the horses and camels go extinct in North America but not elsewhere in the world?
Some extinctions in Africa are likely connected to the rise of humans in this region. A giant pig, giant hippopotamus and giant baboon all went extinct in Africa at this time, even though the average temperature in this area was not terribly cold. The arrival of humans in North America via the Bering Land Bridge about 12,000 to 15,000 years ago corresponds to the extinction of many large mammals in North America about 11,000 years ago. In South America, the arrival of humans about 10,000 years ago corresponds to the extinction of the giant ground sloth. The arrival of humans in Australia and New Zealand between 8,000 and 13,000 years ago corresponds to the extinction of the moa, a giant flightless bird known to have been hunted by humans, and many large marsupials, including the giant kangaroo.
The extinctions of these large mammals is probably not entirely due to hunting by humans. Populations that were already stressed by climatic changes may have been further decimated by hunting. Parasites and diseases have also been implicated as contributing factors. If groups of animals were isolated by glaciations, they could have been ravaged by diseases that could have wiped out small groups of genetically similar animals. Also, during interglaciations (the warmer periods between ice ages), groups that had been isolated might then be brought together again, and infected animals that were resistant to a disease or parasite could then infect animals that had never been exposed to it before, killing them off.
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