Istiodactylidae

Istiodactylid skulls: A) Istiodactylus latidens (NHMUK R3877) (B) Istiodactylus sinensis (NGMC 99-07-11) and (C) Nurhachius ignaciobritoi (IVPP V-13288)

Remains of taxa that can be confidently assigned to Istiodactylidae have been found in the UK and China, in rocks dating from the Early Cretaceous period (Barremian to Aptian stage).[2] Arbour and Currie (2011) described Canadian Gwawinapterus beardi as a member of Istiodactylidae living in the late Cretaceous (upper Campanian stage);[3] however, Witton (2012) suggested the tooth replacement pattern in this animal does not match that of pterosaurs, suggesting that the species might be non-pterosaurian.[2] Additional research suggested that the species was in fact a fish.[4] The earliest known species might be Archaeoistiodactylus linglongtaensis, from the Middle Jurassic of China;[5] however, it also has been suggested that the holotype specimen of this species might actually be a poorly preserved specimen of Darwinopterus.[6] Hongshanopterus, a supposed istiodactylid from China, has been reclassified as a non-istiodactylid member of Ornithocheiroidea of uncertain phylogenetic placement by Witton (2012).[2]

Istiodactylids were medium-sized pterosaurs with flat, rounded jaws similar to that of a duck. They had small teeth lining their jaws, however, and this can mostly be seen in the more advanced genera such as Istiodactylus.[7]

Restoration of an Istiodactylus in flight

Below is a cladogram showing the phylogenetic placement of this group within Pteranodontia from Andres and Myers (2013).[8]

The cladogram below is a topology recovered by Kellner et al. (2019). In the analyses, they recovered Istiodactylidae within the more inclusive group Istiodactyliformes, and assigned both Istiodactylus and Liaoxipterus to a new subfamily called Istiodactylinae, but kept Nurhachius as a basal member.[9]