after basilosaurus leviathan took a shot at top predator. at that time it was the ice age and whales evolved blubber to keep warm in cool areas. At that age however megalodon was top predator living all across the world. However the problem was it was getting colder and as its food disappeared it relied on leviathan as its food not a good idea for a predator to hunt another predator. After megalodon went extinct
The Woolly Rhino died for the same reasons as the woolly mammoths however it most likely survived longer until 4,000 B.C when they were still alive during the egypt rise, but herding woolly rhinos would be hard because they are more dangerous than woolly rhinos
Castoroides ohioensis reached a length of up to 8 ft 2 in and an estimated weight of 130-220 lbs; It lived in North America during the Pleistocene epoch and went extinct at the end of the last Ice Age, 12,000 years ago. Beavers the size of black bears.