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Re: Ah ha! That's where therizinosaurs came from



>>> Dr. Ronald Orenstein wrote:
>
>>> Has anyone come up with an adaptive explanation for the degree of fusion
>>> and finger reduction in the avian hand (including the hand of living
>>> ratites) that does NOT involve supporting a more or less rigid feathered
>>> wing?  I suppose someone will point to alvarezsaurids, but the similarity
>>> does not seem very great (and I suppose they could be secondarily
>>> flightless too).

Do most Recent birds (at least those closer to the basal divergence of
modern birds) use their wings while fighting? Accepting
aprioristically the answer is "yes", before in this thread I came with
the crazy hypothesis, based on Zahavi's ideas on sexual selection for
strong muscles, that the blow force increased because of the pectoral
musculature increase. It may require the extremity of the hand to be
reinforced to resist the energy from the blows, as well as the loss of
the distalmost parts of the hand, because of hteir greater tendence to
break up at impact, because of achieving greater angular acceleration.
Of course, as I know little about the sequence of character state
evolution in the line of inferred ancestors from the most basal
avialians towards modern birds, this may just be plainly wrong.

Cheers,

Augusto