Beretta writes:
Darwinian evolution requires far more than the deformed molecules of mutation to explain the origin of new organs and body plans -it needs beneficial changes in anatomy.
You haven't, I assume, noticed that all amphibians, reptiles, dinosaurs, birds and mammals are tetrapods? The reason? Common heritage.
Tetrapods
Beretta writes:
There is no proof that this is genetically possible.
You're in total denial. There is convergence of evidence across fields such as geology, paleontology, biogeography, comparative anatomy and physiology, molecular biology, genetics, and many others.
Transitional sequences.List of Transitionals