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.

[3] Nyctosaurids are generally characterized as specialized, pelagic soarers like frigatebirds; however, the Alcione species appear to have had shorter wings and possibly have been divers like some modern piscivorous birds.

[5] Analyses by David Unwin did indicate a close relationship between Pteranodon and Nyctosaurus, though he used the name Pteranodontia for the clade containing both genera.

[6] Most nyctosaurid fossils have been found in formations dating to the late Cretaceous period of the western United States and Mexico.

[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.