Random thoughts about pets and extinct animals

I started wondering, what kinds of pets would the larger mammals (like elephants) have? Initially I thought a large snake would be possible, except they would probably all be extinct (since their diet typically consist mostly of smaller mammals). Ostriches and other large birds along with large reptiles/fish seem plausible at least.

Though would extinct animals like the Moa still be around, or would some other mammal have hunted them all? Same for things like the dodo. Either there would be more species because there aren't humans to murder them all, or there would be many ***fewer*** animals, since now we have a bunch of sentient predators of various sizes wandering around eating things.