Dragons of the Air
People are often the under the impression that evolution is somehow progressive, that everything that lived before was inferior to anything you'd find now.
Natural selection works to fine-tune creatures for their survival in a given niche, sure, and over time competition will drive them to perform better than their ancestors. While this is true, it is an oversimplification.
Penguins are well-adapted to life in blisteringly cold conditions, yeah? Well, they're fucked when the ice caps melt. But the ice caps will return, they always do, perhaps a million years later. If penguins were miraculously re-introduced, they'd survive just fine in this environment. But there are no miracles. Penguins are dead.
Likewise, pterosaurs were beautifully adept creatures, dominating the skies for a hundred and fifty million years, give or take. Many recent computer models suggest that the late Cretaceous fliers in particular, like say Quetzalcoatlus, were more efficient than any bird at their task (not to mention they were the size of an airplane).
But like so many creatures, they fucked off into oblivion at the K/T boundary, never to be seen again. If pterosaurs were miraculously re-introduced to present-day Africa, say, they'd certainly give the fauna a run for its money.