Nyctosauridae (meaning "night lizards" or "bat lizards") is afamily of specialized soaringpterosaurs of the lateCretaceous Period ofNorth America,Africa, and possibly other continents includingSouth America. It was named in 1889 byHenry Alleyne Nicholson andRichard Lydekker.^[2]

Nyctosaurids Temporal range:Late Cretaceous,Coniacian–Maastrichtian PreꞒ Ꞓ O S D C P T J K Pg N
Carnegie Museum fossil specimen ofNyctosaurus gracilis, CM 11422
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Order:	†Pterosauria
Suborder:	†Pterodactyloidea
Clade:	†Aponyctosauria
Family:	†Nyctosauridae Nicholson &Lydekker, 1889
Type species
†Pteranodon gracilis Marsh, 1876
Genera[1]
†Alcione? †Barbaridactylus †Epapatelo? †Muzquizopteryx †Nyctosaurus †Simurghia?
Synonyms
Nyctodactylidae Haeckel, 1895

Nyctosaurids are characterized by their lack of all but the wing finger. In most pterosaurs, the hand has four fingers, with the fourth elongated to support the wing, and the remaining three are usually small, clawed, and used in walking or climbing. The lack of functional fingers in nyctosaurids may suggest that they spent almost all of their time in the air, rarely walking on the ground. Nyctosaurids also possessed a distinctively enlarged crest for muscle attachment on their upper arm bone, or humerus, thedeltopectoral crest, hatchet shaped like in the unrelatedrhamphorhynchids.^[3] Nyctosaurids are generally characterized as specialized,pelagic soarers likefrigatebirds; however, theAlcione species appear to have had shorter wings and possibly have been divers like some modern piscivorous birds.^[4]

Nyctosaurids have occasionally been included in the similar familyPteranodontidae, though researchers including Christopher Bennett and Alexander Kellner have both concluded that they belonged to a separate lineage.^[5] Analyses byDavid Unwin did indicate a close relationship betweenPteranodon andNyctosaurus, though he used the namePteranodontia for the clade containing both genera. Both opinions were published before the discovery of the second definitively known nyctosaurid,Muzquizopteryx, in 2006.^[6]

Most nyctosaurid fossils have been found in formations dating to the late Cretaceous period of the westernUnited States andMexico.Nyctosaurus dates from 85-84.5 million years ago, in theNiobrara Formation ofKansas.Muzquizopteryx is the oldest nyctosaurid known from definitive remains, dating to theTuronian-Coniacian boundary inCoahuila.^[7] A possible nyctosaurid specimen from Europe has been reclassified as an azhdarchoid.^[8]

Before the late 2010s, three forms were known from theMaastrichtian: a single potentially nyctosaurid humerus (upper arm bone) from Mexico,"Nyctosaurus" lamegoi from Brazil,^[9][10] and a nyctosaurid complete wing-phalanx1, a claw (digit phalanx manus), and a partial ulna from Jordan. The Jordan specimen is of particular interest as it is the first record of a nyctosaurid from the Old World and represents the latest record of the family (uppermost Maastrichtian).^[11] Beginning in 2016, Nicholas Longrich, David Martill, and Brian Andres presented evidence of several nyctosaurid and pteranodontid species from the latest Maastrichtian age of north Africa, suggesting that these lineages went through an evolutionary radiation in the Old World shortly before the K-Pg extinction event. Three of these pterosaurs were named in 2018, and were calledAlcione,Barbaridactylus, andSimurghia.^[4]

In 2022, Fernandes et al. describedEpapatelo as a new pteranodontian from Angola. IncludingEpapatelo in the phylogenetic analysis of Longrichet al. (2018), they recovered a new clade,Aponyctosauria, composed of the Nyctosauridae,Alcione,Simurghia, andEpapatelo.^[12]

In 2024,Alcione,Simurghia, andEpapatelo were referred to as members of Nyctosauridae based on phylogenetic analysis, and"N." lamegoi was included as a species ofSimurghia.^[1]