Yes, Primal Rage, the bloody fighting game that pitted dinosaurs against giant apes actually took place in a post-apocalyptic landscape. After the fall, animals grew to humongous size as a new Stone Age began. Homo Sapiens are still around, but are now reduced to their primordial selves, basically becoming cavemen in the style of the Flintstones.
Looking on the bright side, humanity still exists, so we’re already doing good compared to some potential doomsday scenarios. It’s too bad that humans have fallen on such hard times, including the loss of every piece of technology, but TV has been replaced with live dinosaur fights. If the cost for seeing that is the end of society and the possibility of being stepped on by thunder lizards, we’re ready to pay that price.