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Re: four winged Archaeopteryx

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.]