Absolutely fascinating! Hope you didn't just make it all up /s
The size of pterodactyls; https://en.wikipedia.org/wiki/Quetzalcoatlus
Pterodactyls could fly from birth: https://www.newscientist.com/article/2284950-baby-pterosaurs...
And the bit on Resource Partitioning in https://www.khanacademy.org/science/ap-biology/ecology-ap/co... has the principle that in the presence of competition, animals focus on whatever niche lets them outcompete.
But while I'm throwing out trivia on flight, have you ever wondered why bats only fly at night? It is because their wings have very thin skin. This is an even better aerodynamic surface than feathers, but offers them NO protection from sunburn!
The only theory I've heard on that front is that being able to both launch and flap with their arms basically allowed them to use the same, larger muscles for both, rather than having to split them, which increased their size ceiling while still being able to launch. http://markwitton-com.blogspot.com/2018/05/why-we-think-gian... (This is more precisely answering the question "how could they get so big?", but still pretty germane.)
I have no idea from which article I ran across the connection between wing structure and juvenile flight. But the idea stuck because I was familiar with heterochrony from having read too much Stephen J. Gould when I was younger. However it is an observable fact that baby bats and birds do not fly, while fossil evidence says that pterosaurs did. The amount of parenting effort that birds require is also well-documented.
> Why did pterosaurs get so much bigger?