I guess that's true. I guess petting zoo chickens could be mellow and the people there would know which I could pet and which would be defensive.
I've gotten the impression that they varied a lot.
Herbivorous dinosaurs--which included sauropods, ankylosaurs, stegosaurs, hadrosaurs, pachycephalosaurs, ornithopods, ceratopsians and titanosaurs--vastly outnumbered meat-eaters in prehistoric times.
Some of which displayed armor and would fend off and even kill predators. From the herbivores they used different tactics to defend and protect themselves from predators. Besides fighting they could run away( fly or swim away if possible). They could also hide. I read that all dinosaurs had the ability to camouflage themselves. They could also seem imposing in hopes to scare the predator away.
Not all dinosaurs were large either. The velociraptor and the protoceratops were small, about child-sized. As I was checking to see if I named the right dinosaur I found out that velociraptors were only about 3 feet long and attacked with a large claw on their foot. It's older cousin Deinonychus was more threatening and actual inspiration behind the Jurassic Park velociraptor.
The single biggest fabrication in the entire Jurassic Park series was when that cute, curious little Dilophosaurus sprayed burning venom in the face of Wayne Knight. Not only wasn't Dilophosaurus poisonous, but to date there's no convincing evidence that any dinosaur of the Mesozoic Era deployed poison in its offensive or defensive arsenal (there was briefly some buzz about Sinornithosaurus, but it later turned out that this dinosaur's "venom sacs" were a actually displaced teeth).