What ecological void was not entirely filled in the Holocene after the megafauna began to disappear?

Answer

The sheer force capable of challenging an adult aurochs

As the climate warmed, the sheer force that could challenge an adult aurochs waned significantly, leaving the species more vulnerable to rising human influence.

What ecological void was not entirely filled in the Holocene after the megafauna began to disappear?
Predatoranimalpreyaurochs