Re: four winged Archaeopteryx

[Richard Cowen <cowen@blueoakfarm.com>]

For my remark about the inability of Archaeopteryx to raise its  
forelimb above horizontal, I accepted Phil Senter's analysis. He also  
says that Confuciusornis lacked this ability also. Obviously this is  
in conflict with Greg Paul's conclusions, and there will have to be  
some resolution of that. In my biased view, the other signs that  
Archaeopteryx flew weakly or not at all make up a more parsimonious  
picture of A as a ground-running displaying feathered little theropod  
than any of the alternatives. We shall see.....

Senter, P. 2006. Scapular orientation in theropods and basal birds,  
and the origin of flapping flight. Acta Palaeontologica Polonica 51:  
305-313.

The fact that bats and pterosaurs don't use a supracoracoideus system  
in their flight doesn't mean that birds can do without it. Bats and  
pterosaurs don't have feathers, but that doesn't mean that birds can  
fly without feathers. These are different packages of adaptations.

The rigid furcula makes sustained flight difficult, but it doesn't  
prevent flight as far as I  can imagine. So I concede that one to  
David Marjanovic. The flexing of the furcula acts to facilitate  
respiratory pumping, so helps to provide the fuel-burning capacity  
that powers sustained flight.

My remark about the tail of Archaeopteryx came from Balmford, A. et  
al. 1993. Aerodynamics and the evolution of long tails in birds.  
Nature 361: 628-631. The bottom line from that paper was that  
Archaeopteryx type tails make flight worse, not better. [Therefore I  
would argue that that tail was selected less for flight than for  
display, or ground maneuvering.]