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Robert Kiely wrote:
>Interesting, perhaps Dromaeosaurs used a thrusting motion to give it more
speed when chasing/pouncing on prey<
This is what I tend to believe, and is very much along the lines of the "pouncing proavis" model I referenced in my earlier post on this topic (the full reference to that article is: Joseph P. Garner, Graham Taylor and Adrian Thomas (1999) On the origins of birds: the sequence of character acquisition in the evolution of avian flight. Proc. R. Soc. London, v. 266:1259-1266.)
I should add (which I forgot to mention earlier) that in addition to providing a strong power stroke, the authors also point out that distally located aerodynamic surfaces would enhance the animal's orientation control by providing a large turning moment.  It seems to me that an adaptation which provided thrust as well as braking and turning control would be an advantage to an active cursorial predator and would provide some of the essential prerequisites for the "ground-up" evolution of powered flight.  An animal with this arrangement of wing feathers wouldn't be a very efficient glider, however, because of the low lift-drag ratio.