Azhdarcho cervicals revisited

Alex Averianov kindly forwarded his 3D scanned images in several views of Azhdarcho cervicals. I tested their ability to dorsiflex and ventriflex. I was able to confirm Averianov’s observation on ventriflexion. The neck does not have the ability to bend down very much past a straight line. However, in dorsiflexion the cervicals appear to have had more travel (Fig. 1) than Averianov observed.

Restored Azhdarcho cervicals in several views. The amount of dorsiflexion appears to be greater that in prior reconstructions.

Figure 1. Click to enlarge. Restored Azhdarcho cervicals in two lateral and one dorsal view. The amount of dorsiflexion appears to be greater that in prior reconstructions by Averianov. Images combined from those provided by Averianov with his permission for web use only.

I restored missing neural spines and zygapophyses. Of course, these are estimates. Also shown above are several dorsal vertebrae. 10-12 are fused to one another as are 13-16 forming a second notarium, the one that articulated with the scapula.

Someday, when we several azhdarchid cervical series to work with, I think we’ll find that relative proportions will be diagnostic across azhdarchid families. This one has two short cervicals (7 & 8) prior to vertebra #9, which has a distinct non-cervical look and typically includes long ribs that do not contact the sternum but would have been within the torso, not the neck. Thus pterosaurs have eight cervicals, not nine. Remember to count the first one as 1 & 2 because #1 is very small and forms the base of the head swivel joint, accepting the occipital condyle.

Neck joints are meant to move and to support the next bone up. Enabling more dorsiflexion appears to provide no immediate benefit, other than a stork-like display.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Averianov AO 2010. The osteology of Azhdarcho lancicollis Nessov 1984 (Pterosauria, Azhdarchidae) from the Late Cretaceous of Uzbekistan. Proceedings of the Zoological Institute RAS. 314(3):264–317.
Averianov AO 2013. Reconstruction of the neck of Azhdarcho lancicollis and lifestyle of azhdarchids (Pterosauria, Azhdarchidae). Paleontological Journal 47 (2): 203-209. DOI: 10.1134/S0031030113020020
http://link.springer.com/article/10.1134/S0031030113020020.
Nesov LA1984. Upper Cretaceous pterosaurs and birds from Central Asia. Paleontologicheskii Zhurnal, 1984(1), 47-57.

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