<i>Infernodrakon hastacollis</i> gen. et sp. nov., a new azhdarchid pterosaur from the Hell Creek Formation of Montana, and the pterosaur diversity of Maastrichtian North America

A considerable number of azhdarchid pterosaur fossils have been recovered from Maastrichtian deposits of North America. Historically, most of these specimens have been referred to <i>Quetzalcoatlus</i> based on a preliminary understanding of the genus. Further study of <i>Quetzalcoatlus</i> and other azhdarchids has increased our understanding of the anatomy and diversity of the clade, and warrants reappraisal of specimens previously referred to this genus. Here we redescribe an azhdarchid cervical vertebra recovered from the Maastrichtian Hell Creek Formation of Montana, U.S.A. Digitization of this specimen via laser scanning allows a more detailed assessment and reconstruction of this specimen’s morphology, revealing both unique characters and unique character combinations. We therefore assign this specimen to a new genus and species of medium-sized azhdarchid, <i>Infernodrakon hastacollis</i> gen. et sp. nov. Phylogenetic analysis recovers <i>Infernodrakon</i> as more closely related to <i>Arambourgiania</i> than to <i>Quetzalcoatlus</i>. Review of Maastrichtian azhdarchid material from North America reveals a high diversity despite the relatively fragmentary fossil record for this clade.