They only eat plants.
those that grind their food, which would be herbivores.
I think plants because dinosaurs that have flat teeth eat plants
Herbivores
FLAT
They use their big and strong teeth in getting or eating food.
they have flat teeth
Animals with hooves usually have flat wider teeth for grinding in back of the mouth and roundish front teeth for pulling. Members of the deer family have only bottom front teeth.
the ones that ones that can rip food...which are fangs.
Cow
If by round, you mean 'not sharp' that would be most of the vegetarian animals, such as: cows, deer and koalas. They have wider flatter teeth in order to chew plants, grass, leaves and vegetation, kind of like the molars humans have in the back of the mouth.
Carnivores have canine teeth
Herbivores have flat teeth that they use to eat plants. Carnivore have the pointy, sharp teeth that they use to rip up their meat. So to answer your question, herbivores have flat teeth.