I mean dire wolves have just as many pups in a litter as ordinary wolves and go into heat just as often. Same can be said of giant bison, saber tooth cats, etc.

I mean dire wolves have just as many pups in a litter as ordinary wolves and go into heat just as often. Same can be said of giant bison, saber tooth cats, etc. We actually don't know precisely when the extinctions occurred or how long it took for them to occur. All we know is where the gaps in the sparse data set that is the fossil record exist. It could be that the extinctions actually made it easier for humans to expand and move into those areas after the fact, or that humans uniquely benefitted from the environmental or situational changes that were ongoing. We know the Younger Dryas was an incredibly intense era of climate change, after the ice age receded it suddenly plunged back into glacial temps for a millenia or two. Very strange and stressful time for species of all types.