Pterosaurs flying reptiles. This category includes:
plesiasaurs are water dwelling Nessie's
They are correctly called Pterosaurs, although they are more commonly refered to as Pteradactyls. There are also prehistoric gliding lizards, but I don't think that's what you're talking about.
While the general public is still under the impression that Pterosaurs were reptiles, there is overwhelming evidence that they were, if fact, warm blooded and thus not reptiles. Flying in a hugely energy intensive task and there are very few cold-blooded animals capable of flight even today- most moths and butterflies are warm blooded, heating their bodies with the waste energry of the flight process. It is doubtful whether there ever was or ever will be a truly flying reptile. Evidence that they were warm blooded includes but is not limited to the evidence showing that dinosaurs were cold blooded (predator/prey ratio of bird-of-prey style pterasaurs, bone spots, rate of evoloutionary dispersion, etc.) as well as the requirement that they be warm blooded to be capable of surviving in their ecological roles without displacement, and many other factors. For more information read The Dinosaur Heresies by Robert Bakker PhD.