A recent study of velociraptor and deinonychus dinosaurs has perhaps finally provided a highly plausible rationale for one of the most vexing evolutionary questions of them all. How did wings evolve?

The evolution of wings has been one of the most contentious debates in evolutionary theory from the time of Darwin. It is still one of the main issues that is latched onto today by those who challenge the theory of evolution.

One of the major arguments that has been difficult to answer in the past is “what use is half a wing?” This question is asked because evolution is said to occur in small steps, but wings are a major departure from all other use of limbs. So if evolution occurs in small steps, then wings should have evolved bit-by-bit. But until the wing provides actual flight, up until now anyway, the argument has been that partially functioning wings provide no evolutionary advantage, and as such would not be selected for, which would negate the further development and stop wings from ever evolving in the first place.

But this study seems to me to have a plausible explanation, based on a study of velociraptor claws and comparing them to modern eagle or hawk claws.

Evolution of flapping

These findings could shed light on the evolution of flight in birds, researchers said. Such feet could have led to the evolution of flapping.

“When a modern hawk has latched its enlarged claws into its prey, it can no longer use the feet for stabilization and positioning,” Fowler said. “Instead, the predator flaps its wings so that the prey stays underneath its feet, where it can be pinned down by the predator’s body weight. The predator’s flapping just maintains its position, and does not need to be as powerful or vigorous as full flight would require. Get on top, stay on top — it’s not trying to fly away.”

In much the same way, raptor dinosaurs might have flapped their feathery limbs to keep stable. [Photos of Fossil Feathers]

“We see fully formed wings in exquisitely preserved dromaeosaurid fossils, and from biomechanical studies we can show that they were also able to perform a rudimentary flapping stroke,” Fowler said. “Most researchers think that they weren’t powerful enough to fly — we propose that the less demanding stability-flapping would be a viable use for such a wing, and this behavior would be consistent with the unusual adaptations of the feet.”

“There’s an old question on the evolution of flight — ‘what use is half a wing?'” Fowler told LiveScience. “I think we have provided the most complete and defensible answer.”

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This is the sort of analysis that I like.