The first fossil was discovered on the English Isle of Wight in 1887, and in 1901 became the holotype specimen of a new species, O. latidens (Latin for "wide tooth"), in the genus Ornithodesmus.

In 1887, the British palaeontologist Harry G. Seeley described a fossil synsacrum (fused vertebrae attached to the pelvis) from the Wessex Formation of the Isle of Wight, an island off the coast of southern England.

[1][2] The British geologist John W. Hulke suggested later that year that Ornithodesmus was a pterosaur, finding it similar to fossils that he had seen before, but Seeley disagreed.

Later researchers have been mystified by the fact that Seeley described the jaws and teeth of O. latidens and named it after the latter, when the only specimen available in 1901, NHMUK R176, does not appear to have had these elements.

Only the back of the skull was listed as present by Lydekker in 1888, but it was rumoured that a set of jaws had been lost from Fox's collection, so it is possible that Seeley had examined them prior to this.

[2][4] In 1913, the British amateur palaeontologist Reginald W. Hooley described two more specimens of O. latidens, collected from the sea after a rockfall near Atherfield Point on the Isle of Wight in 1904, originating from the Vectis Formation.

The first of these, NHMUK R3877, was collected as three blocks and consists of a skull, neck and trunk vertebrae, a shoulder blade, an ischium, and parts of the forelimbs.

latidens to the new genus Istiodactylus; the name is derived from Greek istion, "sail" and daktylos, "finger", referring to the wings of large pterosaurs.

[14] In 2012, the British palaeontologist Mark P. Witton reported the "rediscovery" of a jaw-piece that belonged to specimen NHMUK R3877, found while he was visiting the museum to photograph the skull.

[7][9] In 2022, the Chinese palaeontologist Yizhi Xu and colleagues stated that the difference between Liaoxipterus and both species of Istiodactylus was limited, and that their interrelationship warranted further study.

[16] Howse and colleagues suggested in 2001 that the now missing holotype jaws of I. latidens may be specimen CAMMZ T706, which was recognised in 1982 by the English palaeontologist Jenny A. Clack, but had no documented history prior to the mid-1960s.

[2] In 2021, the Russian palaeontologist Alexander O. Averianov and colleagues suggested that the front ends of an istiodactylid snout and mandible at the Vernadsky State Geological Museum in Moscow, specimen SGM 1810–01, could also be the missing holotype, since analysis of pollen from its matrix showed that it likely came from the Vectis Formation, where I. latidens has been found.

[6] Later writers classified it among the short-tailed pterodactyloids, and from the 1980s and onwards, it was generally found to be closest to Ornithocheirus and Pteranodon, based on computerised phylogenetic analyses.

[26] Since additional members of the family Istiodactylidae were discovered only in the 21st century, with many of those discoveries occurring in quick succession, the interrelationships and exact content of the group are still unclear and need reappraisal.

They are distinguished from other pterosaurs by features such as the shape and position of their teeth, broad snouts, narrowed orbits, and large naso-antorbital fenestrae.

[28] Two fossils from North America formerly thought to have been similar to istiodactylids are now believed to have been misidentified; a mandible fragment from the Morrison Formation probably belongs to another pterosaur group, and Gwawinapterus is most likely a fish.

[9] Archaeoistiodactylus from the Middle Jurassic of China was named in reference to the describers assuming it was ancestral to Istiodactylus, but it was later shown to be the poorly preserved remains of an unrelated wukongopterid.

In 1991, the German palaeontologist Peter Wellnhofer compared the front ends of the jaws of Istiodactylus with those of a duck, while noting it was not a "duck-billed pterosaur" (as it has been popularly called), due to its strong teeth.

[18] Howse and colleagues found that the distinctive teeth indicated a specialised diet or feeding technique, and instead suggested they could have been used to remove chunks of meat from prey or a carcass in the manner of a "cookie cutter" or by biting and twisting the skull.

Witton also discussed an unpublished Ph.D. thesis by the German palaeontologist Michael Fastnacht, wherein biomechanical calculations predicted that Istiodactylus filter-fed in a manner similar to ducks.

Pointing out that the jaws were dissimilar to the broad, flattened, and spatulate bills of ducks, and that the teeth were not suited for filter-feeding, he dismissed the idea of a duck-like lifestyle for Istiodactylus.

Scavenging birds have a mosaic of strong and weak elements in their skulls; they do not have to struggle with their prey, but need to be able to tear and pull morsels from cadavers.

Istiodactylus appears to have had large jaw muscles, and therefore a strong bite, and the skull was deep, which would have helped resist bending when pulling flesh.

Individual bones of the skull were instead slender and shallow, and the toothrows were short, which indicates Istiodactylus did not have the necessary reinforcements for predation, and did not have to subdue struggling prey.

He envisioned that istiodactylids would have to step back from a carcass if more powerful carnivores were attracted to it, but would return to finish the remains when those animals were satiated.

[21] Martill stated that there were many differences between the skull of Istiodactylus and extant scavengers, such as the lack of a sharp, pointed beak, which could have made it less capable of tearing flesh, but the long neck may have provided enough pulling power, and the claws on the fingers may have been used to manipulate carcasses.

[32] Wing elements of Istiodactylus were used to model pterosaur wing-mechanics by Ernest H. Hankin and David M. S. Watson in 1914, and by Cherrie D. Bramwell and George R. Whitfield in 1974, but the details of istiodactylid flight performance have not been studied.

[33][34][9] Witton suggested that istiodactylids would have been powerful fliers, due to an enlarged area for downstroke musculature attachments and well-developed pectoral and upper arm bones, and they probably spent much time in the air.

[10] Dinosaurs from the Wessex Formation include the theropods Ornithodesmus, Neovenator, Aristosuchus, Thecocoelurus, and Calamospondylus; the ornithopods Iguanodon, Hypsilophodon, and Valdosaurus; the sauropods Pelorosaurus and Chondrosteosaurus; and the ankylosaur Polacanthus.

[38] Other animals include gastropods, bivalves, bony fishes, chondrichthyes, lissamphibians, lizards, turtles, crocodilians, birds, and mammals.