So, in Planet Zoo, while animals can harm one another, it's very barebones and that's for two reasons: First off, a player would simply know not to house certain types of animals in the same enclosure. Secondly, there's over a hundred species, and it wouldn't be possible to have animations for every animal fighting every other animal.
I think that in Prehistoric Kingdom, players could be given enough context to separate animals simply by them giving each other threat displays and severely dropping each other's comfort levels, in turn resulting in a poor enclosure score and potentially new negative things like guests refusing to view or donate to bad enclosures.
And, while animals do fight in real life, zoo animals are much less inclined to fight and would be more scared of one another than aggressive, and I think the same should apply for the animals in Prehistoric Kingdom who were quite literally created outside of the natural order, although some could argue that all animals have all of their natural instincts regardless of how they came about.
All of this would be quite the win-win scenario in my opinion: Avoiding lots of unnecessary animating, while providing an in-world explanation for it as well.