with other azhdarchids with preserved cervical vertebrae, and referred to it as a "large azhdarchid pterosaur". This is larger than azhdarchids such as Zhejiangopterus and Montanazhdarcho, and comparable to the smaller species of Quetzalcoatlus, Q. lawsoni; the larger Q. northropi is thought to have reached , thereby being the largest known flying animal. Witton grouped Phosphatodraco with "midsized" azhdarchids based on this size estimate in 2013. In 2010, Kellner suggested this size estimate too large, based on his reinterpretation of the neck vertebra order. Naish and Witton, who followed Kellner's interpretation, listed a neck-length of for Phosphatodraco in 2017, and a wingspan of . There were two main types of azhdarchid skulls; very long, low skulls that were up to ten times longer than wide, and some that were much shorter than that, closer to those of other pterosaurs. Some had crests and some did not. Azhdarchids had necks that were proportionally longer than those of other pterosaurs, and their vertebral column and much of the rest of the skeleton was pneumatized (filled with air-sacs that lightened it). The body skeleton of azhdarchids was small but robust, and their upper arm bones were solidly built. Their wing-metacarpals (the hand bones that connect with the fingers) were relatively the largest among pterosaurs, and the longest bones in the wings; their wing-fingers (which supported the wing-membranes) were relatively short. The pelvises were relatively robust, and the hindlimbs long. Combined, the long-wing metacarpals and legs made azhdarchids relatively taller when standing than other pterosaurs, though their feet were narrow and short. As a pterosaur, Phosphatodraco was covered with hair-like pycnofibers. Cervical vertebrae The suite of features that distinguish a taxon from other related taxa is called a diagnosis, and in the case of Phosphatodraco, these features are all found in the cervical vertebrae. Since Pereda-Suberbiola and colleagues considered the preserved vertebrae to be C5–C9 of the series in their description, that is the diagnosis and description followed here. Note that if Kellner's suggestion that the series actually represents vertebrae C3–C8 is correct, the diagnostic features listed by Pereda-Suberbiola and colleagues may possibly be inaccurate, and the following description would refer to different vertebrae in the series. Pereda-Suberbiola and colleagues found Phosphatodraco to differ from other azhdarchids in that the hindmost vertebra, C8 in their order, is very elongated, 50% longer than C5, and has a prominent neural spine (the spine that projects upwards