RE: New paper on pre-Archaeopteryx coelurosaurian dinosaurs

[evelyn sobielski <koreke77@yahoo.de>]

> Possibly the most scientific approach
> to this question would be to
> look at the whole configuration space of possible leg
> positions, like
> it was done by Hutchinson, Gatesy and some other guy
> (*cough, cough*)
> here:


Good approach, but it still yields too many false positives in ratites. Might 
also be worthwhile to try a physical (sticks-and-rubberbands) model. At least 
an initial assessment of shoulder, knee and hip joint mobility could thus be 
done more easily, and the initial configuration space be constrained. The in 
silico model does not account very well for the bulk of soft tissue; the poses 
3 and 4 in Fig. 3 do not seem to work well in real life because ostriches have 
quite fat thighs, but of course, the algorithm does not know that. It could be 
told, but that is probably a major effort and will shoot calculation time 
through the roof.

Check out how the wrist/elbow configutarion space is constrained in a fresh or 
softened bird skin (ask your local taxidermist or try a plucked chicken); in 
that case it is mainly the skin. At the proximal end of the limbs muscle and 
ligaments should be more significant. This can probably be easily reproduced in 
a model even if you work with fossil material, as long as the major muscle 
scars and ligamental channels are preserved. 


Regards,

Eike