The
Quaternary epoch saw the
extinctions of numerous predominantly larger species, many of which occurred during the transition to the
Holocene epoch in what is termed the
Holocene extinction event. Among the main causes hypothesized by
paleontologists are the spread of
disease, natural
climate change, and
overkill by
humans, which appeared during this epoch. A variant of this last possibility is the
second-order predation hypothesis, which focuses more on the indirect damage caused by overcompetition with nonhuman predators.
The Ice Age extinction event is characterised by the extinction of many large 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, and in Subsaharan Africa only 2 of 44. The South American extinction witnessed the aftermath of the Great American Interchange. Only in South America and Australia did the extinction occur at family taxonomic levels or higher.
There are two main hypotheses concerning the Pleistocene extinction
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 marsupial Australian megafauna. Biologists note that comparable extinctions have not occurred in Africa, where the fauna evolved with hominids. Post-glacial megafaunal extinctions in Africa have been spaced over a longer interval.
