Azhdarchidae

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Azhdarchids Fossil range: Late Cretaceous
Zhenjiangopterus linhaiensis
Conservation status
Extinct (fossil)
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Sauropsida Order: Pterosauria Suborder: Pterodactyloidea Family: Azhdarchidae Nessov, 1984
Genera
See text

Azhdarchids (from Ajdarxo, the name of a dragon in Uzbek mythology. IPA pronunciation: [adʒˈdarχɒ]) were a family of pterosaurs known primarily from the Late Cretaceous period which included some of the largest known flying animals of all time. Originally considered a sub-family of Pteranodontidae, Nessov (1984) named the azhdarchinae to include the pterosaurs Azhdarcho, Quetzalcoatlus, and "Titanopteryx" (now known as Arambourgiania). Azhdarchids are characterized by their extremely long necks, made 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, Quetzalcoatlus, and the closely related family Tapejaridae. Azhdarchids are also distinguished by their relatively large heads and long, spear-like jaws. It has been suggested azhdarchids were skimmers (e.g. Nessov 1984, Kellner and Langston 1996), but some workers have recently cast doubt on this idea (Chatterjee and Templin 2003, Ősi et al., 2005). Their wings were short compared to some other pterosaurs, and might have looked disproportionately short in the larger headed, longer necked species.

[edit] Classification

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.

[edit] Taxonomy

Classification after Unwin (2006).

• Order Pterosauria
  • Suborder Pterodactyloidea
    • Superfamily Azhdarchoidea
      • Family Azhdarchidae
        • Arambourgiania
        • Azhdarcho
        • Bakonydraco
        • Hatzegopteryx
        • Montanazhdarcho
        • Phosphatodraco
        • Quetzalcoatlus
        • Zhejiangopterus
• Possible valid azhdarchid genera
  • Eoazhdarcho
  • Doratorhynchus
  • Bogolubovia
  • Bennettazhia
  • "Ornithocheirus" bunzeli

[edit] References

• Astibia, H , Buffetaut, E , Buscalioni, A D , Cappetta, H , Corrall, C , Estes, R , Garcia-Garmilla, F , Jaeger, J J , Jimenez-Fuentes, E, Loeuff, J Le , Mazin, J M , Orue-Etxebarria, X , Pereda-Suberbiola, J , Powell, J E , Rage, J C , Rodriguez-Lazaro, J , Sanz, J L, and Tong, H (1991) The fossil vertebrates from Lafio (Basque Country, Spain); new evidence on the composition and affinities of the Late Cretaceous continental fauna of Europe Terra Nova, 2, 460-466.

• Bennett, S. C. (2000). Pterosaur flight: the role of actinofibrils in wing function. Historical Biology, 14:255-284.

• Chatterjee, S. and Templin, R. J. 2004. Posture, locomotion, and paleoecology of pterosaurs. Geological Society of America Special Publication 376, 1-64.

• Kellner, A. W. A. & Langston, W. 1996. Cranial remains of Quetzalcoatlus (Pterosauria, Azhdarchidae) from Late Cretaceous sediments of Big Bend National Park, Texas. Journal of Vertebrate Paleontology 16, 222-231.

• Nesov, L A (1984) [Upper Cretaceous pterosaurs and birds from Central Asia]. Paleontologicheskii Zhurnal (1), 47-57.

• Nessov, L A (1990) [Flying reptiles of the Jurassic and Cretaceous of the USSR and the significance of their remains for the reconstruction of palaeogeographic conditions]. Bulletin of Leningrad University, Series 7, Geology and Geography 4(28), 3-10 [In Russian].

• Nessov, L A (1991) [Giant flying reptiles of the family Azhdarchidae: 11. Environment, sedirnentological conditions and preservation of remains]. Bulletin of Leningrad Universitv Series 7, Geology and Geography 3(21), 16-24 [In Russian].

• Ősi, A., Weishampel, D.B., and Jianu, C.M. 2005. First evidence of azhdarchid pterosaurs from the Late Cretaceous of Hungary. Acta Palaeontologica Polonica 50 (4): 777–787.