after the genus' original describer. The holotype specimen of Q. northropi had not been properly described and diagnosed until 2021 and until then the status of the genus Quetzalcoatlus was identified as problematic. Mark Witton and colleagues (2010) noted that the type species of the genus—the fragmentary wing bones comprising Q. northropi—represent elements which are typically considered undiagnostic to generic or specific level, and that this complicates interpretations of azhdarchid taxonomy. For instance, Witton et al. (2010) suggested that the Q. northropi type material is of generalized enough morphology to be near identical to that of other giant azhdarchids, such as the overlapping elements of the contemporary Romanian giant azhdarchid Hatzegopteryx. This being the case, and assuming Q. northropi can be distinguished from other pterosaurs (i.e., if it is not a nomen dubium), perhaps Hatzegopteryx should be regarded as a European occurrence of Quetzalcoatlus. However, Witton et al. also noted that the skull material of Hatzegopteryx and Q. lawsoni differ enough that they cannot be regarded as the same animal, but that the significance of this cannot be ascertained given uncertainty over the relationships of Quetzalcoatlus specimens. These issues can only be resolved by Q. northropi being demonstrated as a valid taxon and its relationships with Q. lawsoni being investigated. An additional complication to these discussions is the likelihood that huge pterosaurs such as Q. northropi could have made long, transcontinental flights, suggesting that locations as disparate as North America and Europe could have shared giant azhdarchid species. Q. lawsoni was found to be a valid taxon in 2021, and confirmed to belong to the same genus as Q. northropi. An azhdarchid neck vertebra, discovered in 2002 from the Maastrichtian age Hell Creek Formation, may also belong to Quetzalcoatlus. The specimen (BMR P2002.2) was recovered accidentally when it was included in a field jacket prepared to transport part of a Tyrannosaurus specimen. Despite this association with the remains of a large carnivorous dinosaur, the vertebra shows no evidence that it was chewed on by the dinosaur. The bone came from an individual azhdarchid pterosaur estimated to have had a wingspan of . Description Size When it was first named as a new species in 1975, scientists estimated that the largest Quetzalcoatlus fossils came from an individual with a wingspan as large as . Choosing the middle of three extrapolations from the proportions of other pterosaurs gave an estimate of 11