Sometimes the fossils are complete enough to see remnants of stomach contents. However, the best clues/evidence comes form the shape of their mouth and the structure of the teeth. Their body morphology also gives clues.
The dinosaur ate his prey slowly.
velocirapter
sientist can not even figure it out yet so go ask your parents
a sientist is a person who studies science
carnivores
It was celophysys a small dinosaur that hunted in groups and ate fish.
I seriously doubt it.
it ate meat
a dinosaur that ate a chicken
Parasaurolophus ate plants from trees.
Plateosaurus was an herbivore, which means that they ate plants.
It was the t Rex and then the folaserrapter