Maybe the lions could eat the elephants. Sorry. This is a HORRENDOUS idea. First off, the climate is absolutely wrong. Even in NM, IT SNOWS! I dunno, but I thought that mammals like Elephants and Lions didn’t handle the cold to well, that’s why they’re in f*cking AFRICA.
Not really. In the Pleistocene, both lions and elephant were present in the cold Eurasian steppes (which were colder than America is today). And in the American steppes actually! They have no trouble with cold. They need a particular make-up of their environment. Elephants need tall grasses. Lions need lost of game animals, with a succesion of grazers oover the seasons. They need particular structures of the buildup of their surroundings.