Cranial Morphology of a Scaphognathus-Like Pterosaur, Jianchangnathus robustus, Based on a New Fossil from the Tiaojishan Formation of Western Liaoning, China

A new pterosaur fossil with an articulated skull and fragmentary postcranial skeleton was collected from the Jurassic Tiaojishan Formation of Linglongta, western Liaoning, China. Its configuration shows an affinity with the Scaphognathus-like Jianchangnathus robustus, which was reported from the same region and horizon. The fossil reveals new cranial morphology: a convex dorsal margin of the skull, antorbital fenestra completely posterior to the naris, a long maxillary process and short quadratojugal process of the jugal, and jaw articulation above the midheight of the mandible; the first upper tooth close to the snout tip, the two anterior-most upper teeth tightly arranged, and the fifth upper tooth positioned at the level of the anterior margin of the naris. Recent discoveries of non-pterodactyloids from the Tiaojishan Formation of northeastern China exhibit a high taxonomic diversity comparable to those in the Solnhofen Limestone. Therefore, as a significant pterosaur assemblage before the Solnhofen Limestone, the Tiaojishan Formation provides a new perspective in understanding the evolution and diversity of the non-pterodactyloids.