| Pterorhynchus | |
|---|---|
 | |
| Skeletal reconstruction showing known material | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Order: | †Pterosauria |
| Clade: | †Darwinoptera |
| Genus: | †Pterorhynchus Czerkas & Ji, 2002 |
| Type species | |
| †Pterorhynchus wellnhoferi Czerkas & Ji, 2002 | |
Pterorhynchus ("wing snout") is an extinctgenus ofpterosaur from the mid-Jurassic agedYanliao Biota[1] ofInner Mongolia,China.
The genus was named in 2002 byStephen Czerkas andJi Qiang. Thetype species isPterorhynchus wellnhoferi. The genus name is derived from Greekpteron, "wing" andrhynchos, "snout", in reference to the tall crest on the head. Thespecific name honours the German pterosaur researcherPeter Wellnhofer.
The genus is based onholotype CAGS02-IG-gausa-2/M 608 (earlier DM 608). It was found inChifeng in the Daohugou Beds. According to JiPterorhynchus belongs to theYanliao Biota from theHaifanggou Formation of theCallovian;Lü Junchang in 2007 ascribed it to the somewhat laterTiaojishan Formation of the same stage. In 2023, it is suggested that taxon is from Haifanggou Formation again.[2]
The only known specimen had an elongated skull 11.8 centimetres (4.6 in) long, a long tail, and awingspan of about 85 centimetres (33 in). This specimen consists of an articulated, nearly complete skeleton with remains of theintegument. These included thewing 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 largekeratin 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 minute 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.
Hair-likepycnofibers covered the body, and tiny tufts of fibers also covered portions of the wing membrane. These were described as pinnate, with many strands arising from a single base (similar to thecalamus of the down feathers in birds), and seen as corresponding to the hypothetical Stage II in the evolution of feathers. This would suggest that pterosaur pycnofibres and dinosaur feathers werehomologous.[3] Later researchers—in a detailed study of pterosaur integument—recognized distinct tufts of fibers, but did not find evidence for the reported diamond-shaped patterns supposedly formed by these tufts when they examined the published photographs. However, they disagreed with the interpretation that the small nodules at the bases of some tufts were similar to a calamus, because they did not appear to be hollow.[4]
The scientists who first studied it assignedPterorhynchus to theRhamphorhynchidae. In his 2006 bookThe Pterosaurs: From Deep Time, David Unwin regarded it as a Cretaceous genus,[5] but this was based on old information. He also suggested that it was ascaphognathine, related toScaphognathus.[5] A large phylogenetic analysis performed by Brian Andres and colleagues in 2014 found thatPterorhynchus was actually a close relative of the similar-lookingwukongopterids, and therefore a closer relative ofpterodactyloid pterosaurs. Andres and colleagues assigned both the wukongopterids andPterorhynchus to the groupDarwinoptera.[6]
