This is one of the two main explanations proposed by evolutionists as to how terrestrial reptiles began to fly. According to this theory, reptiles took to the air vertically, by hopping from the ground. The basic concept is that certain reptiles flapped their forearms very rapidly and for long periods as they chased insects, and that over the course of time, these forelegs developed into wings. Not the slightest explanation is offered, however, for how such a complex structure as a wing could have come into existence from forearms being beaten against one another in order to trap flies.
John Ostrom, a prominent adherent of the cursorial theory, admits that the proponents of both hypotheses can do no more than speculate: “My cursorial predator theory is in fact speculative. But the arboreal theory is also similarly speculative.” 104 (See Arboreal Theory, the.)
Even if we assume that mutations did cause undirected changes in a reptile’s forearms, it is still irrational to expect that any wing could emerge by chance through the addition of cumulative mutations. Any incremental mutation taking place in its forearms would not endow the reptile with functional wings, but would leave it deprived of functioning forearms. This would leave the animal disadvantaged (in other words, defective) compared to other members of its species. According to the rules of the theory of evolution, that deformed creature would be eliminated through natural selection.
Furthermore, according to biophysical research, mutations take place only very rarely. Therefore, it is impossible for these deformed creatures to wait millions of years for their deficient, incomplete wings to be completed through minute mutations.
104 John Ostrom, “Bird Flight: How Did It Begin?.” American Scientist, p. 47.2009-08-14 15:54:30