AZHDARCHID NECKS

[<darren.naish@port.ac.uk>]

On the necks of azhdarchid pterosaurs, Jaime wrote...

> Sibbick's painting is hypothetical, rather than based
> on fact. I guess storks and other long-necked birds
> were the basis of the restoration, but that's a guess.

The Sibbick restoration was done under the supervision of Dave 
Martill, Dino Frey and Lorna Steel and follows work by Frey and 
Martill on the cervical vertebrae of _Arambourgiania_ and 
_Quetzalcoatlus_. This was published in _Neues Jarhbuch_. 
Azhdarchid necks do not seem to have had a great deal of motion - the 
flat-faced centra and way the zygapophyses interlock indicate this - but 
extensive dorsoventral motion could have been posible at the axis-
skull articulation and the thoracic-cervical transition point. These bits 
have yet to be well described for any azhdarchid, so this is speculative. 
Perhaps Jim C could throw in a few comments here.

The idea in the Sibbick painting is (Frey and Martill's) that these 
pterosaurs were slow marine gliders that used ground effect, oriented 
the neck so it was ventral to the most downward excursion of the 
wingtip, and caught fish by grabbing from the water surface. The neck 
is held pretty straight, cranial crests wouldn't be a good idea because 
wind blowing in from the side would place a lot of torque on the neck, 
and a very mobile thoracic-cervical transition point is a necessity. To 
break the water surface with the minimum of resistance the animal also 
has to have very blade-like distal jaws: hence the beak shape in the 
_Arambourgiania_ model. I have a big problem with this in that I think 
contact with the water surface for a flying animal of this size would 
disrupt the glide, even at slow speed. This is something we spend a lot 
of time arguing about.  

"All these memories will be lost in time, like tears in rain"

DARREN NAISH 
PALAEOBIOLOGY RESEARCH GROUP
School of Earth, Environmental & Physical Sciences
UNIVERSITY OF PORTSMOUTH
Burnaby Building
Burnaby Road                           email: darren.naish@port.ac.uk
Portsmouth UK                          tel: 01703 446718
P01 3QL