Tuesday, 17 August 2010

Ornithocheirus wing

Ornithocheirus is well documented in the UK collections, but many of the remains are fragmentary, consisting of partial bones and joint associations. I thought it would be interesting to use some of the specimens to compile a model of a whole wing.  All of the bone ends are preserved and in some cases the lengths of the bones are clear, other bone lengths can be extrapolated.
The main stumbling blocks are identifying the ends of wing phalanges 2 and 3, and scaling the bones to the same sized individual.  The pteroid bone is also an issue since it is seldom preserved or identified in fragmentary remains.  This wing is an estimation for this exercise, based largely on O. sedgwicki remains;
Assembled, this wing has a length of 90cm, giving the whole pterosaur a wingspan of about 2m.  This is a good medium size pterosaur, though many Ornithocheirids were much bigger than this. Coloborhynchus piscator would have had a wingspan of about 4m, which is more typical of the larger Ornithocheirids.

When the wing is examined as a whole it is quite apparent that the joints would have had a limited range of movement, being unable to fold completely.  This is typical of the larger pterosaurs indicating that they would have been very efficient on the wing, but very awkward on the ground.  Pneumatic foramen are observed in all of the main wing bones showing that in life they would have been filled with air, making the wing a very light structure.