Pterorhynchus

Pterorhynchus was a genus of rhamphorhynchid "rhamphorhynchoid" pterosaur from the Middle or Late Jurassic-age Daohugou Formation[1] of Inner Mongolia, China.

The genus was named in 2002 by Stephen Czerkas and Ji Qiang. The type species is Pterorhynchus wellnhoferi. The genus name is derived from Greek pteron, "wing" and rhynchos, "snout", in reference to the tall crest on the head. The specific name honours the German pterosaur researcher Peter Wellnhofer.

The genus is based on holotype CAGS02-IG-gausa-2/M 608 (earlier DM 608). It was found in Chifeng in the Daohugou Beds. According to Ji Pterorhynchus belongs to the Yanliao Biota from the Haifanggou Formation of the Callovian; Lü Junchang in 2007 ascribed it to the somewhat later Tiaojishan Formation of the same stage.

This type specimen consists of an articulated, nearly complete skeleton with remains of the integument. These included the wing membrane, hair-like structures, a long version of the vane found at the end of "rhamphorhynchoid" tails, and a head crest with both a low bony base and a large keratin extension; the latter feature is unusual in "rhamphorhynchoids" (i.e. basal pterosaurs), the fossils of which do not often show head crests. The front part of the extension continued the leading margin of the bone base, extending at quite a sharp angle; it finally curved back to the base of the skull in a rounded curve. The crest covered the posterior two thirds of the head, showed the presence of large oval scales and was reinforced by a dozen ridges running parallel to the rounded trailing edge. At the base a vertical pattern was visible, interpreted as corresponding to the original camouflage colour patterning. The describers ascribed a primarily aerodynamic function to the crest, which is reflected in the genus name. The hairs (pycnofibers) were originally described as pinnate, with many strands arising from a single base (calamus), and seen as corresponding to the hypothetical Stage II in the evolution of feathers. This would suggest that pterosaur hair and dinosaur feathers were homologous.[2] However later researchers—in a detailed study of pterosaur integument—did not agree with this interpretation as they were unable to find evidence for either central-branching patterns or a calamus.[3] The type individual had an elongated skull 11.8 cm (4.65 in) long, a long tail and a wingspan of about 85 cm (33.46 in).

The describers assigned Pterorhynchus to the Rhamphorhynchidae. David Unwin's recent book The Pterosaurs: From Deep Time regarded it as a Cretaceous genus,[4] but this was based on old information. He also suggested that it was a scaphognathine, related to Scaphognathus.