as you can see from the diagram, pterosaurs are not descended from the stem-dinosaurs, thus they cannot be dinosaurs any more than birds could be mammals.
I understand quite well how monophyletic clades work and I hope you understand that they are a human construct. That doesn’t mean they are wrong or bad or something, but the question you are ignoring is: Who decides what the stem dinosaur is and would the decision be the same if they know about pterosaurs? Maybe but maybe not. Now that decision is made and set in stone, there is no going back but “dinosaur” and “ornithodiran” are just words that would be swopped (again, not gonna happen anymore)
They are the direct sister group. It’s kind of a definition thing. People defined dinosaurs before pterosaurs were known so they were not included
it’s not really a definition thing as such, “dinosaur” just means anything descended from a specific point on the tree of life.
Yes, dinosaurs are defined as all descents of the last common ancestor of [blank] and [blank].
I don’t remember what the blanks were but I’m sure they would have included pterosaurs if they knew about them back than
no, that’s not how cladistics works…
as you can see from the diagram, pterosaurs are not descended from the stem-dinosaurs, thus they cannot be dinosaurs any more than birds could be mammals.
https://simple.wikipedia.org/wiki/Cladistics
I understand quite well how monophyletic clades work and I hope you understand that they are a human construct. That doesn’t mean they are wrong or bad or something, but the question you are ignoring is: Who decides what the stem dinosaur is and would the decision be the same if they know about pterosaurs? Maybe but maybe not. Now that decision is made and set in stone, there is no going back but “dinosaur” and “ornithodiran” are just words that would be swopped (again, not gonna happen anymore)