Size and Weight:
Depending on whose reconstruction you believe, Jeholopterus may have been far from your garden-variety pterosaur: this flying reptile was distinguished by its unusually large and sharp claws, its cat-like head with (at least according to one paleontologist) prominent fangs, its widely articulated jaws (meaning it could open it mouth wider than other pterosaurs), and its unusually short tail (for a rhamphorhynchoid pterosaur, that is).
Why did Jeholopterus have so many (presumed) specialized features? As you can imagine, speculation has run rampant: the paleontologist referenced above believes this pterosaur clung to the backs of large terrestrial dinosaurs and sucked their blood, like a modern vampire bat. It's a striking image, but other experts in the field aren't convinced, and the weight of the evidence now is that Jeholopterus may have been much closer to average, pterosaur-wise, than was initially advertised.