Figure 1. Pterodactylus skull, privates collection, from “Weber 2013 Paleoeocology of pterosaurs 3 : Solnhofen”. French Paleontological survey “Fossiles”. Bones colorized below, both images flipped left to right. Black dots indicated fenestra. Anterior slit is secondary naris, which originated in Scaphognathus. Note the jugal and nasal extend to it. The premaxilla appears to have only three teeth, but look more closely and the nubbin-like medial tooth is still visible. Here you can also see the medial sheet bone in the anterior antorbital fenestra. It is not a fossa.
Luckily this specimen was buried before being crushed, so the cracking one sees in other fossils are absent here. Not sure what the rest of the specimen looks like. This privately owned and expertly prepared Pterodactylus specimen can be considered “pristine” and it offers uncluttered insights into the small pterosaur skull, including the tiny nares, the medial sheet dividing the anterior antorbital fenestra, the laminated jugal and nasal, and the nubbin of a medial pmx tooth. Thanks to Frédéric Weber for providing the image.
Figure 2. Closeup of the rostrum of this private Pterodactylus specimen with bone laminations identified. Without other specimens, like Scaphognathus, that show the secondary naris developing, there would be more reason to dismiss these minor shapes as taphonomic cracks and such.
We don’t look at such imagery in a vacuum. Rather we note that this sort of morphology shows up first in Scaphognathus (Fig. 3) and is retained, more or less, in its many pterosaurian descendants.
Figure 3. New reconstruction of Scaphognathus with the new foot and wing phalanges added.
Image from “Frédéric Weber 2013 Paleoeocology of pterosaurs 3 : Solnhofen”. French Paleontological survey “Fossiles.”