Azhdarcho /aːʒˈdɑːrxoʊ/, is a genus of azhdarchid pterosaurs from Central Asia. They originate from the Bissekty Formation in Uzbekistan, which dates back to the middle Turonian stage approximately 92 million years ago. The Zhirkindek Formation in Kazakhstan and possibly the Ialovachsk Formation in Tajikistan also belong to this group of dinosaurs. It is known from fragmentary remnants, such as the characteristically extended neck vertebrae of the family Azhdarchidae, which includes Quetzalcoatlus and many other enormous pterosaurs. The Persian term azhdar (ا{در), which refers to a dragon-like beast in Persian folklore, is where the name Azhdarcho from. Azhdarcho lancicollis serves as the type species. The Latin terms lancea (meaning "lance" or "spear") and collum (meaning "neck") are the source of the specific epithet lancicollis.
History
Lev A. Nesov discovered the fossil remains of Azhdarcho during trips to Central Asia in 1974–1981 in the Kyzyl Kum desert (from the Taykarshinskaya section of the Bissekty Formation). The catalog number ЦНИГРмузeй 1/11915 (TsNIGRmuzey) designates the type specimen, which is composed of an anterior neck vertebra. Twelve paratypes were referred, comprising fragments of the jaw, wing and limb components, and numerous more neck vertebrae. These specimens were placed to the F.N. Chernyshev Central Geologic Exploration Museum in St. Petersburg, together with additional vertebrate fossils that were gathered during the excursions. Nesov described the unusual neck vertebrae of Azhdarcho lancicollis type specimen as being incredibly elongated and spherical in cross section at mid-length. His observations of comparable traits in a number of other pterosaurs were utilized to create the new subfamily Azhdarchinae, which is a subfamily of the Pteranodontidae family. Quetzalcoatlus and Arambourgiania (then called Titanopteryx) were both assigned to this subfamily by Nesov; the latter was later renamed as the family Azhdarchidae. Additionally, he proposed that a species of Azhdarcho might be identified from comparable, thin-walled pterosaur bones found in Wyoming's Lance Formation. He used this as proof of similarities between the faunas of western North America and central Asia during the Late Cretaceous period. The only known species of Azhdarcho at present time is A. lancicollis, as further study has not supported this theory.
Classification
The cladogram below illustrates Azhdarcho's evolutionary position within the group Neoazhdarchia, namely the family Azhdarchidae, of which Azhdarcho is the type genus. The topology that Brian Andres and Timothy Myers discovered in 2013 served as the foundation for the cladogram.
Neoazhdarchia
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Paleobiology
Nesov pointed out in the initial description of Azhdarcho that the pterosaur's neck would have had very little flexibility due to the way the vertebrae articulated. While it could bend its neck vertically to some extent, Azhdarcho was unable to rotate its neck in any way. Nesov hypothesized that pterosaurs, like Azhdarcho, would have eaten by using their long necks to scoop animals out of the water at shallow depths and on the surface, much like current Skimmers do. But new studies have revealed that skimming needs more energy and anatomical adaptations than previously believed, suggesting that big pterosaurs like Azhdarcho were probably not able to skim. The azhdarchid's long neck would have also enabled it to hunt aquatic prey, hunt on the bottom while swimming, or hunt in the air for poorly flying vertebrates. However, Nesov also proposed that the animal would have required stable weather conditions in order to fly well, and that azhdarchid habitats should have been dominated by mild, even winds. Mark Witton's research, however, indicates a different conclusion, namely that azhdarchids were generally terrestrial stalkers.
Azhdarcho reconstruction of it flying over a lake in early morning. Art made by PaleoEquii.
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