As an adult, I get time to think about dinosaurs when we play dinosaurs. What creatures lived in the highlands and the mountains? Did the big dinosaurs live up there, or did just small ones? Were the highland mammal playgrounds, and attract small predators? Did other archosaurs hunt up there? (I can see four-legged archosaurs having an easier time on the mountains.) What were the other populations that we just don't know about?
This idea of other populations just never occurred to me as a kid.
The definition of dinosaur should start: Dinosaur: 1) Any archosaur. 2) Any member of Dinosauria.
Most folks just don't know what the proper definition of a dinosaur is, but they can (mostly) identify archosaurs. (Those protomammals can be pretty confusing, so I won't blame anyone for getting them wrong.) When most kids say that they love dinosaurs, they mean that they love archosaurs. You get the idea. The word usage is scientifically inaccurate but linguistically sound. Take any sample of people in the English speaking world, and most of 'em will use the word wrong in the exact same way. (Popular consensus is really the way that language works.)