Mongolian Cretaceous fossil localities;Gobiazhdarcho is known from the Burkhant locality in Area D (Bayanshiree Formation)
In 1995, a joint paleontological expedition between the Hayashibara Museum of Natural Sciences and theMongolian Paleontological Center conducted fieldwork in theGobi Desert of Mongolia. At the 'Burkhant' locality of theBayanshiree Formation inDornogovi Province, workers collected three associated cervical (neck) vertebral elements. These specimens,accessioned as MPC−Nd 100/302, include theatlantoaxis (fused first and second cervicals), the third cervical, and theposterior (back) part of the sixth cervical (identified as the fourth by Averianov in 2014).[1][2] In 2009, Mahito Watabe and colleagues described this specimen, in addition to another isolated pterosaur cervical vertebra from the 'Bayshin Tsav' locality of the same formation. The authors refrained from naming either specimen, but discussed their anatomy and likelyphylogenetic affinities in depth.[3]
In 2025, R. V. Pêgas, Xuanyu Zhou, and Yoshitsugu KobayashidescribedGobiazhdarcho tsogtbaatari as a new genus and species of pterosaurs based on the 'Burkhant azhdarchid' fossil remains. Thegeneric name,Gobiazhdarcho, combines "Gobi", a reference to the discovery of the specimen in the Gobi Desert, with "azhdarcho", derived fromazhdar, a dragonlike creature inPersian myth. Thespecific name,tsogtbaatari, honors Mongolian paleontologistKhishigjav Tsogtbaatar [ja]. In the same publication, the authors also named the Bayshin Tsav specimen as another new azhdarchid,Tsogtopteryx.[1]
Prior to the naming ofGobiazhdarcho andTsogtopteryx, the only pterosaur named from Mongolia was thedsungaripteridNoripterus parvus,[4] known from theTsagan-Tsab Formation.[1] Several fragmentary indeterminate pterosaur remains are also known from the country, including a possibleanurognathid,anhanguerid,[5] andtapejaroid,[6] in addition to a possible azhdarchid long bone found in the stomach of adromaeosaurid dinosaur and the very fragmentary remains of a giant azhdarchid.[7][8]
Atlantoaxis (left) and fourth cervical vertebra (right) of the holotype
Based on the size of the holotype vertebrae (third cervical 9.06 centimetres (3.57 in) long), thewingspan ofGobiazhdarcho was estimated at 3–3.5 metres (9.8–11.5 ft), which is comparable in size toEurazhdarcho,Wellnhopterus, andZhejiangopterus. The specimen likely belongs to a late subadult individual that was nearly skeletally mature (fully grown). This was determined based on the lack of a grained texture often seen in immature pterosaur bones and the full fusion of the atlas and axis—both characteristics of mature pterosaurs—combined with the lack of ribs fused to the vertebra, an indication of immaturity. In comparison, the coevalTsogtopteryx was fully grown but much smaller, with a 1.6–1.9 metres (5.2–6.2 ft) wingspan.[1]
To determine the relationships and affinities ofGobiazhdarcho, Pêgas and colleagues scored it in a comprehensive pterosaur-focusedphylogenetic matrix modified from Zhou et al. (2025),[9] deriving from Pêgas (2024)[4] and other earlier publications, with modifications based on newer literature. Their analyses recoveredGobiazhdarcho as thesister taxon toNipponopterus in an early-branching clade within the cladeQuetzalcoatlini, which includes azhdarchids more closely related toQuetzalcoatlus thanHatzegopteryx. The results are displayed in thecladogram below:[1]
Speculativelife restoration ofGobiazhdarcho (larger; red) andTsogtopteryx (smaller; blue) in a Bayanshiree environment with theornithopod dinosaurGobihadros
Gobiazhdarcho is known from the 'Burkhant' locality of theBayanshiree Formation. Examinations of themagnetostratigraphy of the formation confirm that it lies entirely within theCretaceous Long Normal, which lasted only until the end of theSantonian stage.CalciteU–Pb measurements estimate the age of the Bayanshiree Formation from 95.9 ± 6.0 million to 89.6 ± 4.0 million years ago, in theAlbian throughSantonian ages.[12][13] Considering all available evidence, there are likely two distinct levels of the formation—an 'upper' and 'lower'—partially based on faunal differences: a lower part lasting from theCenomanian to lateTuronian ages and an upper part lasting the late Turonian to Santonian ages in the lateCretaceous period.[14] The Burkhant is part of the upper Bayanshiree.[1]
Fluvial,lacustrine andcaliche-based sedimentation indicates a lessersemi-arid climate, with the presence of wet environments composed of largemeanders andlakes. Large-scale cross-stratification in many of thesandstone layers at the Baynshire and Burkhant localities seems to indicate largemeandering rivers, and these large water bodies may have drained the eastern part of theGobi Desert.[15][12]
^Voris, Jared T.; Zelenitsky, Darla K.; Kobayashi, Yoshitsugu; Modesto, Sean P.; Therrien, François; Tsutsumi, Hiroki; Chinzorig, Tsogtbaatar; Tsogtbaatar, Khishigjav (2025-06-11). "A new Mongolian tyrannosauroid and the evolution of Eutyrannosauria".Nature.doi:10.1038/s41586-025-08964-6.
^Kobayashi, Y.; Barsbold, R. (2005). "Reexamination of a primitive ornithomimosaur,Garudimimus brevipes Barsbold, 1981 (Dinosauria: Theropoda), from the Late Cretaceous of Mongolia".Canadian Journal of Earth Sciences.42 (9):1501–1521.Bibcode:2005CaJES..42.1501K.doi:10.1139/e05-044.hdl:2115/14579.
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