Ah, mixed species, a wonderful design element of most modern zoos when it comes to management and education! Though in real life, some animals are more challenging to mix with others, based on temperament alone. Many people often assume herbivores are all peaceful due to being vegan, but that's far from the truth in a realistic scenario (I.e. zebras, rhinos, hippos)
There are a few temperaments/archetypes that are noticeable when it comes to mixed species communities (especially when it comes to aquariums or in a major case, real mixed species enclosures in zoos)
- Peaceful - a lot of dither/easygoing species that would easily tolerate other species as long as they're not predatory/aggressive (which could cause stress/predation if done wrong). For example: Psittacosaurs, Dryosaurs, Leallyannasaura, Muttaburrasaurus
- Semi-aggressive - Can tolerate peaceful species (to an extent, they may still engage in aggressive behavior based on circumstance) and aggressive species, and so, can be mixed with either depending on the accommodations provided, and based on which animal you house them with. For example: Nasutoceratops, Parasaurolophus, Lambeosaurus, Pachyrhinosaurus, Gallimimus
- Aggressive - Potentially highly territorial, and may attack other species in the community if not housed properly. These animals may tolerate bigger ones in a proper setting, though animals with similar niches should be avoided to prevent competition (I.e. Stegosaurus and Ankylosaurus). For example: Stegosaurus, Apatosaurus, Brontosaurus, Triceratops, Styracosaurus
- Predator - This part is mostly dedicated to carnivores/piscivores, since terrestrial communities work slightly differently than aquatic communities. Since predation is still a threat, you wouldn't really wanna do mixed species enclosures with them unless you have a workaround (I.e. real zoos using cheetahs and rhinos, possible since both species are accommodated well, and cheetahs cannot hunt rhinos due to their size diff.)