New Insights into the Skull of <em>Istiodactylus latidens</em> (Ornithocheiroidea, Pterodactyloidea)

<div><p>The skull of the Cretaceous pterosaur <em>Istiodactylus latidens</em>, a historically important species best known for its broad muzzle of interlocking, lancet-shaped teeth, is almost completely known from the broken remains of several individuals, but the length of its jaws remains elusive. Estimates of <em>I. latidens</em> jaw length have been exclusively based on the incomplete skull of NHMUK R3877 and, perhaps erroneously, reconstructed by assuming continuation of its broken skull pieces as preserved <em>in situ</em>. Here, an overlooked jaw fragment of NHMUK R3877 is redescribed and used to revise the skull reconstruction of <em>I. latidens</em>. The new reconstruction suggests a much shorter skull than previously supposed, along with a relatively tall orbital region and proportionally slender maxilla, a feature documented in the early 20^th century but ignored by all skull reconstructions of this species. These features indicate that the skull of <em>I. latidens</em> is particularly distinctive amongst istiodactylids and suggests greater disparity between <em>I. latidens</em> and <em>I. sinensis</em> than previously appreciated. A cladistic analysis of istiodactylid pterosaurs incorporating new predicted <em>I. latidens</em> skull metrics suggests Istiodactylidae is constrained to five species (<em>Liaoxipterus brachyognathus</em>, <em>Lonchengpterus zhoai</em>, <em>Nurhachius ignaciobritoi</em>, <em>Istiodactylus latidens</em> and <em>Istiodactylus sinensis</em>) defined by their distinctive dentition, but excludes the putative istiodactylids <em>Haopterus gracilis</em> and <em>Hongshanopterus lacustris</em>. <em>Istiodactylus latidens</em>, <em>I. sinensis</em> and <em>Li. brachyognathus</em> form an unresolved clade of derived istiodactylids, and the similarity of comparable remains of <em>I. sinensis</em> and <em>Li. brachyognathus</em> suggest further work into their taxonomy and classification is required. The new skull model of <em>I. latidens</em> agrees with the scavenging habits proposed for these pterosaurs, with much of their cranial anatomy converging on that of habitually scavenging birds.</p>