Recovering lost time in Syria: a gigantic latest Cretaceous azhdarchid pterosaur from the Palmyrides mountain chain

Azhdarchidae was a diverse group of toothless pterosaurs and one of the few lineages of flying reptiles to survive to the end of the Cretaceous. Despite including medium-sized forms, the group is notable for their gigantic representatives, which correspond to the largest known flying animals. Azhdarchids had a nearly global distribution during the Late Cretaceous, including the Arabian Plate, with records in Lebanon and Jordan, such as the iconic Arambourgiana philadelphiae. Here, we report the first azhdarchid, and indeed the first pterosaur, from Syria, recovered from early Maastrichtian phosphate deposits of the Palmyrides mountain chain, near Palmyra (Tadmur). It corresponds to a fragmentary left humerus, missing both its proximal and distal ends, with a preserved length of 289 mm. The Syrian pterosaur was exceptionally large, with extrapolations suggesting that, if complete, its humerus would be only about 10% smaller than the holotype humerus of Quetzalcoatlus northropi, the largest known pterosaur. The new pterosaur fossil also represents the uncommon record of a giant azhdarchid in marine deposits, confirming that these gigantic animals, though classically considered continental, could also inhabit nearshore environments. The find also underscores the widespread occurrence of gigantic azhdarchids until the latest Cretaceous, just prior to their Cretaceous/Paleogene extinction, and highlights the potential for fossil discoveries in understudied regions such as the Middle East.