<P> The Quaternary period saw the extinctions of numerous predominantly megafaunal species, which resulted in a collapse in faunal density and diversity, and the extinction of key ecological strata across the globe . The most prominent event in the Late Pleistocene is differentiated from previous Quaternary pulse extinctions by the widespread absence of ecological succession to replace these extinct species, and the regime shift of previously established faunal relationships and habitats as a consequence . The earliest casualties were incurred at 130,000 BCE (the start of the Late Pleistocene), however the great majority of extinctions in Afro - Eurasia and the Americas occurred during the transition from the Pleistocene to the Holocene epoch (13,000 BCE to 8,000 BCE). However, this extinction wave did not stop at the end of the Pleistocene, but continued, especially on isolated islands, in human - caused extinctions, although there is debate as to whether these should be considered separate events or part of the same event . Among the main causes hypothesized by paleontologists are overkill by the widespread appearance of humans and natural climate change . A notable modern human presence first appeared during the Middle Pleistocene in Africa, and started to establish continuous, permanent populations in Eurasia and Australasia from 80,000 BCE, and the Americas from 22,000 BCE . A variant of the former possibility is the second - order predation hypothesis, which focuses more on the indirect damage caused by overcompetition with nonhuman predators . Recent studies have tended to favor the human - overkill theory . </P> <P> The Late Pleistocene extinction event saw the extinction of many mammals weighing more than 40 kg . The proportional rate of megafauna extinctions is consecutively larger the greater the migratory distance from Africa . </P>

When did the megafauna of north america go extinct