Biology:Gobiazhdarcho

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Gobiazhdarcho (lit. Gobi Desert azhdar) is an extinct genus of azhdarchid pterosaurs known from the Late Cretaceous Bayanshiree Formation of Mongolia. The genus contains a single species, Gobiazhdarcho tsogtbaatari, known from a three cervical (neck) vertebrae. It was closely related to Quetzalcoatlus and coexisted with Tsogtopteryx, another azhdarchid more closely related to Hatzegopteryx.

Discovery and naming

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 the Mongolian Paleontological Center conducted fieldwork in the Gobi Desert of Mongolia. At the 'Burkhant' locality of the Bayanshiree Formation in Dornogovi Province, workers collected three associated cervical (neck) vertebral elements. These specimens, accessioned as MPC−Nd 100/302, include the atlantoaxis (fused first and second cervicals), the third cervical, and the posterior (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 likely phylogenetic affinities in depth.[3]

In 2025, R. V. Pêgas, Xuanyu Zhou, and Yoshitsugu Kobayashi described Gobiazhdarcho tsogtbaatari as a new genus and species of pterosaurs based on the 'Burkhant azhdarchid' fossil remains. The generic name, Gobiazhdarcho, combines "Gobi", a reference to the discovery of the specimen in the Gobi Desert, with "azhdarcho", derived from azhdar, a dragonlike creature in Persian myth. The specific name, tsogtbaatari, honors Mongolian paleontologist Khishigjav Tsogtbaatar. In the same publication, the authors also named the Bayshin Tsav specimen as another new azhdarchid, Tsogtopteryx.[1]

Prior to the naming of Gobiazhdarcho and Tsogtopteryx, the only pterosaur named from Mongolia was the dsungaripterid Noripterus parvus,[4] known from the Tsagan-Tsab Formation.[1] Several fragmentary indeterminate pterosaur remains are also known from the country, including a possible anurognathid, anhanguerid,[5] and tapejaroid,[6] in addition to a possible azhdarchid long bone found in the stomach of a dromaeosaurid dinosaur and the very fragmentary remains of a giant azhdarchid.[7][8]

Description

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), the wingspan of Gobiazhdarcho was estimated at 3–3.5 metres (9.8–11.5 ft), which is comparable in size to Eurazhdarcho, Wellnhopterus, and Zhejiangopterus. 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 coeval Tsogtopteryx was fully grown but much smaller, with a 1.6–1.9 metres (5.2–6.2 ft) wingspan.[1]

Classification

To determine the relationships and affinities of Gobiazhdarcho, Pêgas and colleagues scored it in a comprehensive pterosaur-focused phylogenetic 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 recovered Gobiazhdarcho as the sister taxon to Nipponopterus in an early-branching clade within the clade Quetzalcoatlini, which includes azhdarchids more closely related to Quetzalcoatlus than Hatzegopteryx. The results are displayed in the cladogram below:[1]

Azhdarchidae
Phosphatodraconia

Template:Clade hidden

 
 
 
 

Zhejiangopterus linhaiensis

 
 
 

Mistralazhdarcho maggii

 
 

Aerotitan sudamericanus

 
 
 
 
 

Azhdarcho lancicollis

 
Quetzalcoatlida
Hatzegopterygia
 

Tsogtopteryx mongoliensis

 
 
 

Cryodrakon boreas

 
 
 

Albadraco tharmisensis

 
 
 

Hatzegopteryx thambema

 
 
 
 
 
Quetzalcoatlini
 
 

Nipponopterus mifunensis

 
 

Gobiazhdarcho tsogtbaatari

 
 
 
 
 

Arambourgiania philadelphiae

 
 

Infernodrakon hastacollis

 
 
 
 

Thanatosdrakon amaru

 
 

Quetzalcoatlus lawsoni

 
 

Quetzalcoatlus northropi

 
 

aff. Quetzalcoatlus sp. (FSAC-OB 14)[10]

 
 
 
 
 
 
 
 

Paleoenvironment

Speculative life restoration of Gobiazhdarcho (larger; red) and Tsogtopteryx (smaller; blue) in a Bayanshiree environment with the ornithopod dinosaur Gobihadros

Gobiazhdarcho is known from the 'Burkhant' locality of the Bayanshiree Formation. Examinations of the magnetostratigraphy of the formation confirm that it lies entirely within the Cretaceous Long Normal, which lasted only until the end of the Santonian stage. Calcite U–Pb measurements estimate the age of the Bayanshiree Formation from 95.9 ± 6.0 million to 89.6 ± 4.0 million years ago, in the Albian through Santonian ages.[11][12] 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 the Cenomanian to late Turonian ages and an upper part lasting the late Turonian to Santonian ages in the late Cretaceous period.[13] The Burkhant is part of the upper Bayanshiree.[1]

Fluvial, lacustrine and caliche-based sedimentation indicates a lesser semi-arid climate, with the presence of wet environments composed of large meanders and lakes. Large-scale cross-stratification in many of the sandstone layers at the Baynshire and Burkhant localities seems to indicate large meandering rivers, and these large water bodies may have drained the eastern part of the Gobi Desert.[14][11]

A vast faunal diversity is known in the formation, comprising dinosaur and non-dinosaur genera. The large dromaeosaurid Achillobator is also recognized from the Burkhant locality.[15][1] Theropod dinosaurs from other localities include the therizinosaurs Duonychus, Erlikosaurus, Enigmosaurus, and Segnosaurus,[16] the tyrannosauroid Khankhuuluu,<ref name="Khankhuuluu">{{Cite journal |last1=Voris |first1=Jared T. |last2=Zelenitsky |first2=Darla K. |last3=Kobayashi |first3=Yoshitsugu |last4=Modesto |first4=Sean P. |last5=Therrien |first5=François |last6=Tsutsumi |first6=Hiroki |last7=Chinzorig |first7=Tsogtbaatar |last8=Tsogtbaatar |first8=Khishigjav |date=2025-06-11 |title=A new Mongolian tyrannosauroid and the evolution of Eutyrannosauria

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Pêgas, R. V.; Zhou, Xuanyu; Kobayashi, Yoshitsugu (2025). "Azhdarchid pterosaur diversity in the Bayanshiree Formation, Upper Cretaceous of the Gobi Desert, Mongolia". PeerJ 13. doi:10.7717/peerj.19711. 
  2. ↑ Averianov, Alexander (2025-08-11). "Review of taxonomy, geographic distribution, and paleoenvironments of Azhdarchidae (Pterosauria)". ZooKeys 432: 1–107. doi:10.3897/zookeys.432.7913. ISSN 1313-2970. PMID 25152671. 
  3. ↑ Watabe, Mahito; Tsuihiji, Takanobu; Suzuki, Shigeru; Tsogtbaatar, Khishigjav (2009). "The First Discovery of Pterosaurs from the Upper Cretaceous of Mongolia" (in en). Acta Palaeontologica Polonica 54 (2): 231–242. doi:10.4202/app.2006.0068. ISSN 0567-7920. https://www.app.pan.pl/archive/published/app54/app54-231.pdf. 
  4. ↑ 4.0 4.1 Pêgas, Rodrigo V. (2024-06-10). "A taxonomic note on the tapejarid pterosaurs from the Pterosaur Graveyard site (Caiuá Group, ?Early Cretaceous of Southern Brazil): evidence for the presence of two species" (in en). Historical Biology: 1–22. doi:10.1080/08912963.2024.2355664. ISSN 0891-2963. https://www.researchgate.net/publication/381306918. 
  5. ↑ Bakhurina, Natalia N.; Unwin, David M. (1995). "A survey of pterosaurs from the Jurassic and Cretaceous of the former soviet union and Mongolia" (in en). Historical Biology 10 (3): 197–245. doi:10.1080/10292389509380522. ISSN 0891-2963. 
  6. ↑ Andres, Brian; Norell, Mark A. (2005-03-24). "The First Record of a Pterosaur from the Early Cretaceous Strata of Öösh (Övörkhangai; Mongolia)" (in en). American Museum Novitates 3472: 1–6. doi:10.1206/0003-0082(2005)472<0001:TFROAP>2.0.CO;2. ISSN 0003-0082. 
  7. ↑ Hone, David; Tsuihiji, Takanobu; Watabe, Mahito; Tsogtbaatr, Khishigjaw (2012-05-01). "Pterosaurs as a food source for small dromaeosaurs" (in en). Palaeogeography, Palaeoclimatology, Palaeoecology 331-332: 27–30. doi:10.1016/j.palaeo.2012.02.021. 
  8. ↑ Tsuihiji, Takanobu; Andres, Brian; O'connor, Patrick M.; Watabe, Mahito; Tsogtbaatar, Khishigjav; Mainbayar, Buuvei (September 2017). "Gigantic pterosaurian remains from the Upper Cretaceous of Mongolia" (in en). Journal of Vertebrate Paleontology 37 (5). doi:10.1080/02724634.2017.1361431. ISSN 0272-4634. 
  9. ↑ Zhou, Xuanyu; Ikegami, Naoki; Pêgas, Rodrigo V.; Yoshinaga, Toru; Sato, Takahiro; Mukunoki, Toshifumi; Otani, Jun; Kobayashi, Yoshitsugu (March 2025). "Reassessment of an azhdarchid pterosaur specimen from the Mifune Group, Upper Cretaceous of Japan". Cretaceous Research 167. doi:10.1016/j.cretres.2024.106046. ISSN 0195-6671. Bibcode: 2025CrRes.16706046Z. 
  10. ↑ Longrich, Nicholas R.; Martill, David M.; Andres, Brian; Penny, David (2018). "Late Maastrichtian pterosaurs from North Africa and mass extinction of Pterosauria at the Cretaceous-Paleogene boundary". PLOS Biology 16 (3). doi:10.1371/journal.pbio.2001663. PMID 29534059. 
  11. ↑ 11.0 11.1 Hicks, J. F.; Brinkman, D. L.; Nichols, D. J.; Watabe, M. (1999). "Paleomagnetic and palynologic analyses of Albian to Santonian strata at Bayn Shireh, Burkhant, and Khuren Dukh, eastern Gobi Desert, Mongolia". Cretaceous Research 20 (6): 829–850. doi:10.1006/cres.1999.0188. Bibcode: 1999CrRes..20..829H. https://www.academia.edu/1229640. Retrieved 2020-01-26. 
  12. ↑ Kurumada, Y.; Aoki, S.; Aoki, K.; Kato, D.; Saneyoshi, M.; Tsogtbaatar, K.; Windley, B. F.; Ishigaki, S. (2020). "Calcite U–Pb age of the Cretaceous vertebrate-bearing Bayn Shire Formation in the Eastern Gobi Desert of Mongolia: usefulness of caliche for age determination". Terra Nova 32 (4): 246–252. doi:10.1111/ter.12456. Bibcode: 2020TeNov..32..246K. 
  13. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named A&S_correlation
  14. ↑ Samoilov, V. S.; Benjamini, C. (1996). "Geochemical features of dinosaur remains from the Gobi Desert, South Mongolia". PALAIOS 11 (6): 519–531. doi:10.2307/3515188. Bibcode: 1996Palai..11..519S. 
  15. ↑ Perle, A.; Norell, M. A.; Clark, J. (1999). "A new maniraptoran Theropod – Achillobator giganticus (Dromaeosauridae) – from the Upper Cretaceous of Burkhant, Mongolia". Contributions from the Geology and Mineralogy Chair, National Museum of Mongolia (101): 1–105. OCLC 69865262. https://drive.google.com/open?id=1FtVZYSTmgXXBejYfYDKUIg-giwJXNy39. 
  16. ↑ Kobayashi, Yoshitsugu; Zelenitsky, Darla K.; Fiorillo, Anthony R.; Chinzorig, Tsogtbaatar (2025-03-25). "Didactyl therizinosaur with a preserved keratinous claw from the Late Cretaceous of Mongolia" (in English). iScience 28 (4). doi:10.1016/j.isci.2025.112141. ISSN 2589-0042. Bibcode: 2025iSci...28k2141K. 

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