Size and Weight:
The exact size of Rhamphorhynchus depends on how you measure it--from the tip of its beak to the end of its tail, this pterosaur was less than a foot long, but its wings (when fully extended) stretched for a distance of three feet from tip to tip. With its long, narrow beak and sharp teeth, it's clear that Rhamphorhynchus made its living by dipping its head into the lakes and rivers of late Jurassic Europe and scooping up wriggling fish (and possibly frogs and insects)--much like a modern pelican.
One detail about Rhamphorhynchus that sets it apart from other ancient reptiles is the spectacularly preserved remains of this genus found at Solnhofen in Germany--some of this pterosaur's fossils are so complete that they show not only its bone structure, but the outlines of its internal organs. The only creature to have left comparably intact remains was another Solnhofen discovery, Archaeopteryx--which, unlike Rhamphorhynchus, occupied a place on the evolutionary line that led to the first prehistoric birds.
Because Rhamphorhynchus was discovered so early in modern paleontological history--in Germany, in 1825--it has lent its name to an entire class of pterosaurs distinguished by their small sizes and long tails. Among the most famous "rhamphorhynchoids" are Dorygnathus, Dimorphodon and Peteinosaurus, which ranged across western Europe during the Jurassic period; these stand in stark contrast to later "pterodactyloid" pterosaurs, which tended to larger sizes and smaller tails.