Scaphognathus crassirostris (Goldfuss 1830) GPIB 1304, No. 109 of Wellnhofer 1975, Late Jurassic ~150 mya, was originally considered a type of Pterodactylus. Scaphognathus was derived from a sister to Sordes and Pterorhynchus and phylogenetically preceded progressivily smaller specimens of Scaphognathus, SMNS 59395 and the Maxberg specimen, no. 110.
Distinct from Sordes, the skull of Scaphognathus had a smaller orbit, smaller teeth and more robust bones. A secondary naris appeared at the junction of the premaxilla and maxilla.
The neural spines were shorter.
The sternal complex included two small lateral processes. The deltopectoral crest of the humerus was angled medially. A large trochlear joint was present distally. The fingers were longer and the unguals were larger.
The pelvis was more robust.
As in several other lines of pterosaurs, the descendants of Scaphognathus crassirostris are all progressively smaller. This phylogenetic size decrease drove morphological changes that appeared in larger, more derived taxa. These taxa are widely considered juveniles of larger taxa, but their morphological differences are great and the similarities to Scaphognathus identify them as relatives. Accepting this fact is the key to understanding the family tree of the Pterosauria.
See the family tree of the Scaphognathia here. See the family tree of the Pterosauria here.