Rhamphorhynchus ( "beak snout") is a genus of long-tailed pterosaurs in the Jurassic period.https://en.wikipedia.org/wiki/Pterosaur
Most pterosaur skulls had elongated jaws with a full complement of needle-like teeth. In some cases, fossilized keratinous beak tissue has been preserved, though in toothed forms, the beak is small and restricted to the jaw tips and does not involve the teeth.http://onlinelibrary.wiley.com/doi/10.1111/evo.12684/full
The avian beak is a key evolutionary innovation whose flexibility has permitted birds to diversify into a range of disparate ecological niches.Pterosaurs already had keratinous beak tissue.
However, the abrupt geometric gap between nonbeaked archosaurs [eg. dinosaurs] and birds and stem birds with beaks may suggest a rapid, comparatively saltational transformation. The difference in ontogenetic trajectories of shape change between nonbeaked forms, in which the premaxilla becomes shorter and broader with time, and beaked forms, in which it becomes longer and narrower, also suggests a discontinuous distinctiveness to the beak.
On the other hand, a dino to bird beak evolution requires a saltational transformation.
Scansoriopterygidae dinosaurs were very small, bipedal dinosaurs, the size of sparrows and pigeons. They had also a few quite amazing features, such as a unusually long third finger on the hand, beaks, and very short tails with very long feathers at the end of it.