Oddly, while investigating Pleistocene Africa, I was surprised to learn that little has changed, other than human over-population and "progress" of course.
I looked up Merck's rhinoceros. Found nothing said about these rhinos living in Africa. They were roughly the size of the African white rhino.
The giant warthog was actually, from what I have found, the size of modern warthogs.
The long-horned buffalo could weigh as much as 4,400 pounds. Rivaled in size among bovine only by the giant bison in North America.
The African Aurocks of the Pleistocene could weigh up to 3,300 pounds. As big as the biggest gaur.
*Even during the Pleistocene, it appears that the African lion had no large predators as rivals.
*There was the Atlas bear in North Africa which was probably a subspecies of brown bear. Reportedly, they were small bears ( I'm guessing maybe 300 pounds tops ).