The skulls of Anurognathus ammoni
(right) and Rhamphorhynchus muensteri
(left), with what amounts to the major jaw-related differences between them. It's been assumed that Rhampho is a pelagic, sea-faring consumer of fishes and such, while Anuro is an inland bug specialist, generally due to comparisons to frogmouths and similar birds. Both of these pterosaurs, oddly enough, lived at the same time, for anurognathids are generally considered much more "primitive" (splitting off the pterosaur family tree before rhamphorhynchids did) and in the same place (the lagoons and island chain that would become central Europe of the latest Jurassic.
More here: qilong.wordpress.com/2014/02/2…
- where I go into more detail. The above illustration, as a teaching tool, may be freely downloaded.