Cycnorhamphus suevicus, a pterosaur from the Late Jurassic of Germany and France (~150-145 mya).
It had a wingspan of about 1.3m (4′3″), and was originally thought to look similar to Pterodactylus with long straight jaws – but a well-preserved fossil nicknamed “the Painten Pelican” revealed its snout was actually much more oddly-shaped.
It turns out Cycnorhamphus’s jaws arced outwards, creating an opening that seems to have become more pronounced as individuals reached adulthood. Soft-tissue impressions in the fossil also show some sort of stiff “flanges” on each side of the upper jaws, covering the gap and giving it a sort of bulldog-like appearance.
The function of this jaw structure is unknown for certain, but it’s been speculated to be a specialization for cracking open hard-shelled prey like molluscs.