Jurassic Park has a moment where Ellie Sattler is literally elbow deep in triceratops poop. It was a pile of poop as big as a person.
..........so, my question is, if dog shit smells different than cat shit, then how would directors know which scent of shit would best accentuate that scene's full realistic immersion?
Dogs are omnivores, while cats were until recently carnivores. Triceratops is a herbivore, so it would have likely smelled more like a dog's. Probably not that much different than a cow's.