why are pterosaurs and aquatic marine animals in the past not considered dinosaurs?

Question

why are pterosaurs and aquatic marine animals in the past not considered dinosaurs?

In: 4

Answer 1

I’ve literally explained this to <5 year olds before (I used to work at a museum). Basically, pterosaurs/marine reptiles aren’t dinosaurs for a few reasons, but an easy one to remember is that their hips are different. Dinosaur hips point their legs straight down (like ours!) and pterosaurs/marine reptiles have their hips point their legs to the side (like a crocodile).