Whether Pleistocene rewilding occurred or not

Pleistocene rewilding is the advocacy of the reintroduction of extant Pleistocene megafauna, or the close ecological equivalents of extinct megafauna. It is an extension of the conservation practice of rewilding, which involves reintroducing species to areas where they became extinct in recent history (hundreds of years ago or less). Towards the end of the Pleistocene era (roughly 13, 000 to 10, 000 years ago), nearly all megafauna of Eurasia, Australia, and South/North America, dwindled towards extinction, in what has been referred to as the Quaternary extinction event. With the loss of large herbivores and predator species,  niches important for ecosystem functioning were left unoccupied. In the words of the biologist Tim Flannery, "ever since the extinction of the megafauna 13, 000 years ago, the continent has had a seriously unbalanced fauna". This means, for example, that the managers of national parks in North America have to resort to culling to keep the population of ungulates under control. Paul S. Martin (originator of the Pleistocene overkill hypothesis states that present ecological communities in North America do not function appropriately in the absence of megafauna, because much of the native flora and fauna evolved under the influence of large mammals.