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Re: Evidence For a Feathered Velociraptor...
Actually, yes. There's a chapter in, IIRC, Mesozoic Vertebrate Life
which investigates the biomechanics of various theropod forelimbs. On
the one end of the range the authors find *Tyrannosaurus*, followed by
*Allosaurus*: all speed sacrificed for power -- short, massive,
columnar bones, small range of motion at each joint, distal muscle
attachments (in part accomplished by shortening the bones). On the
other they find the birds (an eagle was used), followed by
*Deinonychus*: all power sacrificed for speed -- long, gracile bones,
large ranges of motion, proximal muscle attachments.
An interesting paper that I will have to look over again. One caveat
is that the particular aspects or usage of "power" should be clearly
defined. Eagles, in particular, have bones capable of taking very high
loads (both bending and torsion) and tremendous mass-specific power.
Granted, much of the power from their high muscle mass goes to moving
limbs quickly, but there is still plenty of power input.
Of course, you were paraphrasing, and what I figure you mean is that
large theropods were found to maximize output force rather than lever
arm excursion, and birds were found to favor the opposite (except
perhaps in the distal hindlimb of the eagle, which is obviously highly
derived within birds). The reason that I am splitting hairs on this is
that in the evolution of flight, power to mass ratios are critical.
Flying animals tend to generate greater power (and loads) relative to
their weight than their non-flying counterparts of similar mass, though
the distribution of such power and loads is also quite altered (such
that power generation is highly concentrated in muscle groups related
to the limbs).