Pterosaur Behavior:
Aside from size, the pterosaurs of the Jurassic and Cretaceous differed from one another in two major ways: feeding habits and decoration. Normally, paleontologists can infer a pterosaur's diet from the size and shape of its jaws, and by looking at analogous activities in modern birds (like pelicans or seagulls). Pterosaurs with sharp, narrow beaks most probable subsisted on fish, while anomalous genuses like Pterodaustro fed on plankton (its thousand or so teeth shaped a filter, like that of a sperm whale) and the fanged Jeholopterus may have sucked dinosaur blood similar to a vampire bat (though this has yet to be irrefutably proved).
Like modern birds, some pterosaurs also had rich ornamentation--not brilliantly colored feathers, which pterosaurs not at all managed to evolve, but famous head crests. For example, Tupuxuara's rounded crest was rich in blood vessels, a clue that it may have changed color in mating displays, while Ornithocheirus had matching crests on its higher and lower jaws (though it's indistinct if these were used for display or feeding purposes).
Pterosaur Physiology:
The key trait that distinguished pterosaurs from the land-bound dinosaurs that evolved into birds was the nature of their wings-- which consisted of wide flaps of skin related to an extended finger on every hand. Although these flat, broad structures provided copiousness of lift, they may have been better suited to passive gliding than powered, flapping flight, as evidenced by the supremacy of true birds by the end of the Cretaceous period (which may be attributed to their augmented maneuverability).
Although they're only distantly related, ancient pterosaurs and contemporary birds may have shared one important feature in common: a warm-blooded metabolism. There's evidence that some pterosaurs (like Sordes) sported coats of prehistoric hair, a feature generally associated with warm-blooded mammals, and it's unclear if a cold-blooded reptile could have generated enough internal energy to maintain itself in flight.
Like modern birds, pterosaurs were also eminent by their sharp vision (a requirement for hunting from hundreds of feet in the air!), which entailed a bigger-than-average brain than terrestrial or marine reptiles. Using advanced techniques, scientists have even been capable to reconstruct the size and shape of the brains of some pterosaur genuses, proving that they contained more advanced coordination centers than analogous reptiles.
