What happened 50,000 years ago that wiped out many species from this planet?

The crisis of rapid extinction of animals has largely been thought to be a result of climate change, but a new study claims that ‘human pressures’ were the key drivers to these extinction. About 50,000 years ago, our planet earth was home to 57 megaherbivores, and now only 11 of them remain alive, which is an 81% extinction rate. Megaherbivores are large herbivores that can exceed 1000 kg in weight.These megaherbivores are recognized as playing an important role in the functioning of the biosphere and subsequently the earth.
In the late quaternary period hundreds of mammals species disappeared due to human hunting activities. The other species suffered limited extinction during this period. This human intervention in the natural ecosystem was responsible for the extinction of more than 160 species of animals and many megafaunas. These megafaunas were responsible for molding vegetation patterns and dispersing seeds of certain hardwood tree species.
This research by the Danish National Research Foundation's Center for Ecological Dynamics in a Novel Biosphere (ECONOVO) at Aarhus University, bases their study on certain points. One of them being that this Quaternary extinction was a global phenomenon and not unique to an area or climate. Secondly, the extinctions were ‘size selective’ with only large selective vertebrates going extinct and did not extend to the smaller animals. These facts point toward the relation of this global event with the ‘spread and cultural evolutions of Home sapiens. These mass extinctions had happened in the Pleistocene age too and were linked directly with climate change. But those were neither size specific nor species specific.
These losses have not been made up for even in the present times. With people finally paying special attention to the relationship between animals and their environment, the earth’s megafauna are still in a dire state. 47% of all living mammals have been declared vulnerable, endangered or critically endangered by the International Union for the Conservation of Nature (IUCN), and an additional 12% are listed as near threatened. The further loss of megafauna has been widely reported in the past millennia. In China elephants and rhinoceros have seen a deep decline in numbers. Animals like water buffalo, equid and gibbon have become globally extinct. The socio-technological development in humans is being considered the primary reason for the extinction of these species.