Diopecephalus

In 1837 Johann Andreas Wagner named a new species of pterosaur, Pterodactylus kochi, from the incredible Upper Jurassic Solnhofen Limestone in Germany. The original specimen is an articulated and largely complete juvenile skeleton. Over the years, several additional specimens, many of them juveniles, were referred to this species. 

In 1871 Harry Govier Seeley named a new genus for this species, Diopecephalus. He also referred Pt. cristatus and Pt. longicollum to this genus, but they are now the type species of the genera Germanodactylus and Ardeadactylus respectively. Diopecephalus was named to house all of the pterosaurs then known to have a merged nostril and antorbital fenestra. This feature is now known to be present in all short-tailed pterodactyloid pterosaurs as well as the transitional wukongopterids. 

Seeley did not provide an etymology for Diopecephalus, which was a common practice at the time of its publication. The name probably translates to “see-through head,” taking the Greek words “diopao” (to see through) and “kephali” (head). If this is indeed a correct translation, this is probably in reference to the extremely large fenestrae seen in the skull of the holotype specimen of D. kochi. 

Diopecephalus is quite similar to the contemporaneous species Pterodactylus antiquus. Indeed, many pterosaur specialists consider D. kochi to be a species of the genus Pterodactylus, or the same species as Pt. antiquus itself. Most specimens once thought to belong to D. kochi have been shown to be juveniles of Pterodactylus, Ctenochasma, Germanodactylus, and other pterodactyloids. 

However, in 2014 and 2017 Steven Vidovic and David Martill resurrected the genus Diopecephalus for several reasons. First, they note that the holotype specimen and some other referred specimens have proportions that differ from Pterodactylus. In Diopecephalus there are longer bony processes on its cervical vertebrae, less robust hand bones, and a more robust prepubis with a broader distal fan. 

Secondly, when Pt. antiquus and D. kochi are both included in a phylogenetic analysis of pterosaurs, Vidovic and Martill found that they were parts of different pterosaur lineages. Diopecephalus was found to be the most basal member of the ctenochasmatoid lineage, while Pterodactylus was found to be a basal pterodactyloid outside the lineage including the ctenochasmatoids, ornithocheiroids, and azhdarchoids. Additionally, Vidovic and Martill found that the two species of Germanodactylus were not close to the ctenochasmatoids as many other phylogenetic analyses find, but instead part of the broad azhdarchoid lineage close to the dsungaripterids. 

When Diopecephalus lived, about 150 million years ago, much of Europe was flooded by a shallow tropical sea. There were many low-lying arid islands hosting dozens of species of pterosaurs, as well as the first bird Archaeopteryx. Diopecephalus likely patrolled the shore, probing for small invertebrate prey. Like many pterosaurs found in marine environments, it may have fished as well.