The
Rhamphorhynchoidea forms one of the two
suborders of
pterosaurs and represent an
evolutionary grade of primitive members of this group of flying
reptiles. This suborder is
paraphyletic in relation to the
Pterodactyloidea, which arose from within the Rhamphorhynchoidea, not from a more distant common ancestor. Because it is not a completely natural grouping, Rhamphorhynchoidea is not used as a formal group in most scientific literature, though some pterosaur scientists continue to use it as an informal grouping in popular works, such as
The Pterosaurs: From Deep Time by David Unwin, and in some formal studies. Rhamphorhynchoids were the first pterosaurs to have appeared, in the late
Triassic Period (
Norian age, about 210 million years ago). Unlike their descendants the pterodactyloids, most rhamphorhynchoids had teeth and long tails, and most species lacked a bony crest, though several are known to have crests formed from soft tissue like
keratin. They were generally small. Nearly all had become extinct by the end of the
Jurassic Period, though least one
anurognathid genus,
Dendrorhynchoides, persisted to the early Cretaceous. The family
Wukongopteridae, which shows a mix of rhamphorynchoid and pterodactyloid features, is known from the
Daohugou Beds which are most commonly dated to the Jurassic, but a few studies give a Cretaceous date. Further more, remains of a non-pterodactyloid from the
Candeleros Formation extend the presence of basal pterosaurs into the at least early Late Cretaceous.