I wanted to add some data regarding evolution by hybridization, as that better explains the fossil record, and what you describe as pretty radical interventions. www.macroevolution.net is the website where Dr. Eugene McCarthy, the author of the bible in it's field 'The Handbook of Avian Hybrids', explains his hypothesis, and reveals considerable evidence of radical interventions in evolution of species. One of the bizarre facts he discusses is the Platypus, that seems so like a hybrid between mammals and birds, and that the Platypus in fact has whole sections of both bird and mammal genes, almost impossible to believe that such DNA could arise by coincidence.

It's very interesting and you might be very glad to have a look.