SANDCOLEIFORMES&FLUTTERING

["Matthew Troutman" <m_troutman@hotmail.com>]

True enough - of course no living bird has a long flexible tail.  I 
wonder how rigid the tail of Caudipteryx was? 

>From the paper:

"Almost two-thirds of the tail of NGMC-4-A is preserved as a straight 
rod, but the vertebrae are not fused.  The first six haemal spines are 
elongate, rodlike structures.  More posterior haemal spines decrease in 
height, but expand anteriorly and posteriorly."

<<I am not familiar with the Sancoleiformes - a
>fossil taxon, I presume?>>

They're described in _Papers in Avian Paleontology_ by Peter Houde and 
Storrs Olson.  There are 4 definite species: Sandcoleus, Anneavis, 
Eobucco, and Chascacocolius; and two possible species: Uintornis and 
Botauroides.  They are most similliar to colies in most of their anatomy 
and show some other similiairities to some members of the Pici, 
particulary the Indicatoridae.  You want to know more?  I have just 
scratched the surface of the sandcolies.

<<Do you have the reference for Caple?  Gee, someone else thought of 
this too....>>

Caple, G., R.P. Balda, and W.R. Willis 1983.  The Physics of Leaping 
Animals and the Evolution of Preflight.  The American Naturalist 
Vol.121, no.4.  455-476.

<<I have not done this, of course, but I have suggested here that any 
extension of a leap, or slowing of a fall back, could be of use in 
getting at prey slightly out of reach of "mere" leapers, or in making a 
display leap more striking.  Thus even a slight development in that 
direction could be selectively advantageous.>>

Still, you have to overcome the problems of gravity and selkection would 
probably favor them to become better leapers, not fliers.  Rayner also 
found ideas like this unlikely because it will involve simultaneous 
selection and decoupling of the fore- and hindlimbs. 

<<This again assumes that the function of proto-flapping was to get from 
point A to point B.  This need not have been the case; many flycatching 
birds return to their original perch after an aerial foray, and 
displaying leapers are only trying to show off, not to get anywhere.  
Under such circumstances I don't think much in the way of aerodynamic 
stability need to have been involved.>>

Aerodynamic stability is found in all sorts of flying.  Fluttering for 
display still is conjectural and it still needs some sort of control to 
evolve into flight.  

Matt Troutman

______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com