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Re: How did dromaeosaurs use their arms?
>There is virtually no chance that such a specifically winglike forelimb
articulation would have evolved in a grounded cursorial predator.<
The argument that this arrangement was selected as a more effective
"predatory strike" mechanism are, I think, weak for a number of reasons.
But I also don't accept the argument that it couldn't have evolved in a
cursorial predator for other reasons. Research has shown that feathers,
even simple covert-type feathers, significantly decrease aerodynamic drag
over a surface. That's a significant aerodynamic effect which is not just
relevant for flight but also for ground based manueverability. Hypertrophy
of the arms and the feathers on the distal edge of the arm in feathered
theropods (which is what the fossil record appears to show) seems a
reasonable result of selection for enhanced manueverabilty among cursors, as
does the evolution of a mechanism to "fold" those hypertrophied arms towards
the body when not in use.