Parapsicephalus (meaning "beside arch head") is a genus of long-tailed rhamphorhynchid pterosaurs from the Lower Jurassic Whitby, Yorkshire, England.

Within the Rhamphorhynchidae, Parapsicephalus has been synonymized with the roughly contemporary Dorygnathus; this, however, is not likely given the many differences between the two taxa, including the aforementioned convex top surface of the skull.

The top end of the fenestra is enclosed by the thin, rectangular, and slightly concave nasal, and the lacrimal, which is not well-preserved but may have been long, slender, and triangular.

On the underside of the skull, the maxilla forms the majority of the palate (not the premaxilla, as previously assumed[7]), extending back from below the external nostrils.

[1] At the back of the antorbital fenestra is the jugal, which has often been illustrated as a small V-shaped, two-pronged structure,[7] but it is actually large and has four prongs.

Although mostly obscured, the removal of the parietal during preparation has exposed part of the endocast of the brain, which has a large flocculus and cerebrum.

[1] The frontal, which is located on the top of the skull between the premaxilla and the eye socket, takes the shape of a sub-rectangle with a large, rhombic process extending forward to meet the nasal.

Contacting the rear ends of both the frontal and jugal is the thin and triangular postorbital, about 15 millimetres (0.59 in) long along the bottom, extends backwards to separate the infratemporal and supratemporal fenestrae.

Behind the postorbital and closing off the supratemporal fenestra is the three-pronged squamosal, which is partially overlapped by the robust, spatula-like paroccipital processes of the occipital.

[12] Later, in 1919, Gustav von Arthaber, based on the shape of the top of the skull, the elongated nostrils and prefrontal bones, the large antorbital fenestra and eye socket, the deep jugal, and the presence of seven teeth in the maxilla, referred GSM 3166 to the new genus Parapsicephalus.

[1][13] In 2003, David Unwin, Kenneth Carpenter, and others suggested that Parapsicephalus was actually closer to the roughly contemporaneous Dorygnathus from German deposits.

[2][19][20][21] However, a 2017 redescription of GSM 3166 noted a number of ways in which Dorygnathus differed from Parapsicephalus: the greater angle of the lacrimal process of the maxilla, the more reduced maxillary process of the premaxilla, the broader angle of the jugal beneath the eye socket, the overall thinner jugal relative to skull height, the more rounded the eye socket, the more oval-shaped supratemporal fenestra, and the convex top of the skull (which is unique among pterosaurs except for dimorphodontians).

[21][22] Characters which support this placement include the convex top of the skull, the pear-shaped eye socket, the angle of the quadrate, and the thick jugal.

Within the Rhamphorhynchidae, unlike the scaphognathines, the antorbital fenestra is more than twice as long as it is tall,[8][14] and has a concave back margin; the angle of the quadrate is also more than 120°.

[10] A number of marine reptiles are known from this locality: the ichthyosaurs Stenopterygius, Temnodontosaurus, and Eurhinosaurus; the plesiosaurs Eretmosaurus, Sthenarosaurus, and Microcleidus; and the thalattosuchians Steneosaurus and Pelagosaurus.