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Re: bauplan convergence



At 03:57 PM 6/18/00 -0400, Patrick Norton wrote:
Ken Kinman wrote:

>I believe protofeathers first evolved for...(snip)...(t)hen the aerodynamic
developments followed.<

The fossil record suggests that the sequence leading up to flapping avian
flight was that the "folding wrist" came first; then feathers,

If by this you mean elongate feathers on the arm, or pinnate feathers of modern appearance, then I consider this a good possibility. But I suspect that proto-feathers as body covering and/or display devices long preceded the origin of the "folding wrist".


 then flapping
flight. I say this based on my understanding that some form of a semilunate
carpal block (which allows the avian "folding wrist" motion) sems to be more
inclusive than the Maniraptora (possibly also within the Allosaurids), that
feathers are found only within the Maniraptora

I think it is far too early to reach that conclusion. For most other dinosaur groups we simply have no cogent evidence one way or the other regarding body covering (especially in the smaller forms more likely to have retained body covering).


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May the peace of God be with you.         sarima@ix.netcom.com