Istiodactylidae is a small

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

pterosaur Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is an extinct clade of flying reptiles in the order, Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 to ...

s. This family was named in 2001 after the type genus ''

Istiodactylus ''Istiodactylus'' is a genus of pterosaur that lived during the Early Cretaceous period, about 120 million years ago. The first fossil was discovered on the English Isle of Wight in 1887, and in 1901 became the holotype specimen of a new species ...

'' was discovered not to be a member of the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

Ornithodesmus ''Ornithodesmus'' (meaning "bird link") is a genus of small, dromaeosaurid dinosaur from the Isle of Wight in England, dating to about 125 million years ago. The name was originally assigned to a bird-like sacrum (a series of vertebrae fused to ...

''.

Systematics and distribution

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 The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

period (

Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma (million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is preceded ...

Aptian The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), a ...

stage).

Arbour Arbor(s) or Arbour(s) may refer to: Arts and entertainment * ''Arbor'' (installation), a 2013 public artwork in Indianapolis, Indiana, US * Arbor, a counterweight-carrying device found in theater fly systems * ''The Arbor'', a 1980 play by Andr ...

and Currie (2011) described Canadian ''

Gwawinapterus ''Gwawinapterus beardi'' is a species of saurodontid ichthyodectiform fish from the Late Cretaceous period of British Columbia, Canada. While initially described as a very late-surviving member of the pterosaur family Istiodactylidae, further ex ...

beardi'' as a member of Istiodactylidae living in the late Cretaceous (upper Campanian stage); 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. Additional research suggested that the species was in fact a fish. The earliest known species might be ''

Archaeoistiodactylus linglongtaensis ''Archaeoistiodactylus'' is an extinct genus of wukongopterid pterosaur from the Middle Jurassic of China. Discovery and naming ''Archaeoistiodactylus'' is known from an incomplete skeleton with a partial skull and lower jaws. Catalogued as holo ...

'', from the

Middle Jurassic The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations co ...

of China; however, it also has been suggested that the holotype specimen of this species might actually be a poorly preserved specimen of '' Darwinopterus''. ''

Hongshanopterus ''Hongshanopterus'' is a genus of pterodactyloid pterosaur from the Lower Cretaceous Jiufotang Formation of Liaoning, China. The type species ''Hongshanopterus lacustris'' was in 2008 named and described by Wang Xiaolin, Diogenes de Almeida C ...

'', a supposed istiodactylid from China, has been reclassified as a non-istiodactylid member of Ornithocheiroidea of uncertain phylogenetic placement by Witton (2012). 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 ''

''.

Classification

Below is a cladogram showing the phylogenetic placement of this group within Pteranodontia from Andres and Myers (2013). The cladogram below is a topology recovered by Kellner ''et al.'' (2019). In the analyses, they recovered Istiodactylidae within the more inclusive group

Istiodactyliformes Ornithocheiromorpha (from Ancient Greek, meaning "bird hand form") is a group of pterosaurs within the suborder Pterodactyloidea Pterodactyloidea (derived from the Greek words ''πτερόν'' (''pterón'', for usual ''ptéryx'') "wing", a ...

, and assigned both ''Istiodactylus'' and ''Liaoxipterus'' to a new subfamily called Istiodactylinae, but kept ''Nurhachius'' as a basal member.

Paleobiology

Lifestyle

Unlike most ornithocheiroids, istiodactylids bear physiologies suited to a terrestrial life and many of their fossils have been found in freshwater-deposits. Istiodactylids are considered to be pterosaurian equivalents to vultures: acting as the clean-up crew in their native locations. Whether or not istiodactylids could swim like most water-loving pterosaurs remains a mystery.

References

{{Taxonbar, from=Q522434 Pteranodontoids Early Cretaceous first appearances Early Cretaceous genus extinctions Prehistoric reptile families