Temporal range: Late Cretaceous, 108–66 Ma Possibly earlier
|Reconstructed skeleton of Quetzalcoatlus northropi|
Azhdarchidae (from اژدرها (Aždarha), the Persian word for dragon) is a family of pterosaurs known primarily from the late Cretaceous Period, though an isolated vertebra apparently from an azhdarchid is known from the early Cretaceous as well (late Berriasian age, about 140Ma ago). Azhdarchids included some of the largest known flying animals of all time. Originally considered a sub-family of Pteranodontidae, Nesov (1984) named the azhdarchinae to include the pterosaurs Azhdarcho, Quetzalcoatlus, and "Titanopteryx" (now known as Arambourgiania). They were among the last known surviving members of the pterosaurs, and were a rather successful group with a worldwide distribution. By the time of the end-Cretaceous mass extinction, most pterosaur families except for the Azhdarchidae disappear from the fossil record, but recent studies indicate a wealth in pterosaurian faunas, including pteranodontids, nyctosaurids, tapejarids and several indeterminate forms. Some taxa like Navajodactylus, Bakonydraco and Montanazhdarcho were moved from Azhdarchidae to other clades.
Azhdarchids are characterized by their long legs and extremely long necks, made up of elongated neck vertebrae which are round in cross section. Most species of azhdarchids are still known mainly from their distinctive neck bones and not much else. The few azhdarchids that are known from reasonably good skeletons include Zhejiangopterus and Quetzalcoatlus. Azhdarchids are also distinguished by their relatively large heads and long, spear-like jaws. It had been suggested azhdarchids were skimmers, but further research has cast doubt on this idea, demonstrating that azhdarchids lacked the necessary adaptations for a skim-feeding lifestyle, and that they may have led a more terrestrial existence similar to modern storks and ground hornbills.
Azhdarchids were originally classified as close relatives of Pteranodon due to their long, toothless beaks. Others have suggested they were more closely related to the toothy Ctenochasmatids (which include filter-feeders like Ctenochasma and Pterodaustro). Currently it is widely agreed that azhdarchids were closely related to pterosaurs such as Tupuxuara and Tapejara.
Classification after Unwin 2006, except where noted.
- Family Azhdarchidae
- ?Bakonydraco (possible tapejarid)
- ?Montanazhdarcho (non-azhdarchid azhdarchoid, probably a tapejarid)
- "Ornithocheirus" bunzeli
- Possible valid azhdarchid genera
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