| abstract
| - The Late Pleistocene extinction event saw the extinction of many mammals weighing more than 40 kg.
* In North America around 33 of 45 genera of large mammals became extinct.
* In South America 46 of 58
* In Australia 15 of 16
* In Europe 7 of 23
* In Subsaharan Africa only 2 of 44 The extinctions in the Americas entailed the elimination of all the larger (over 100 kg) mammalian species of South American origin, including those that had migrated north in the Great American Interchange. Only in North America, South America, and Australia, did the extinction occur at family taxonomic levels or higher. There are three main hypotheses concerning the Pleistocene extinction:
* The animals died off due to climate change associated with the advance and retreat of major ice caps or ice sheets.
* The animals were exterminated by humans: the "prehistoric overkill hypothesis" (Martin, 1967).[1]
* The extinction of the woolly mammoth (by whatever cause, perhaps by humans) changed the extensive grasslands to birch forests, and subsequent forest fires then changed the climate.[2] We now know that immediately after the extinction of the mammoth that birch forests replaced the grasslands and that an era of significant fire began.[3] There are some inconsistencies between the current available data and the prehistoric overkill hypothesis. For instance, there are ambiguities around the timing of sudden extinctions of Australian megafauna.[1] Biologists note that comparable extinctions have not occurred in Africa and South or Southeast Asia, where the fauna evolved with hominids. Post-glacial megafaunal extinctions in Africa have been spaced over a longer interval. Evidence supporting the prehistoric overkill hypothesis includes the persistence of certain island megafauna for several millennia past the disappearance of their continental cousins. Ground sloths survived on the Antilles long after North and South American ground sloths were extinct. The later disappearance of the island species correlates with the later colonization of these islands by humans. Similarly, dwarf woolly mammoths died out on remote Wrangel Island 1,000 years after their extinction on the mainland. Steller's sea cows also persisted in seas off the isolated and uninhabited Commander Islands for thousands of years after they had vanished from the continental shores of the north Pacific.[4] Alternative hypotheses to the theory of human responsibility include climate change associated with the last glacial period and the Younger Dryas event, as well as Tollmann's hypothetical bolide, which claim that the extinctions resulted from bolide impact(s). Such a scenario has been proposed as a contributing cause of the 1,300 year cold period known as the Younger Dryas stadial.[citation needed] This impact extinction hypothesis is still in debate due to the exacting field techniques required to extract minuscule particles of extra terrestrial impact markers such as Iridium at a high resolution from very thin strata in a repeatable fashion, as is necessary to conclusively distinguish the event peak from the local background level of the marker.[citation needed] The debate seems to be exacerbated by infighting between the Uniformitarianism camp and the Catastrophism camp.[
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