I'm under the impression that the criterion
for being a dinosaur was having a hole in the hip.
Is that correct ?
I'm not sure off hand. I think the info Farmerman provided should answer your question.
My main point to Bewildered was that many things people generically call "Dinosaurs" were technically reptiles. For example, Pterosaurs were "flying reptiles", not Dinosaurs. Yet many people refer to them as Dinosaurs.
And even among the other "Dinosaurs", there were Theropods and Sauropods and probably a lot of other flavors as well. I think the original term just meant something like Terrible or Wondrous Lizard.