You can't just speed up the rate of mutation. Because most mutations are harmful, there's a balance point - beyond this point, you simply weaken the species. Thus, organisms are designed to mutate at specified speeds (which may or may not have variations on the mutation rates of different genes), which are their optimal mutation rates.
The Permian explosion took, what, 50 million years? You're talking about 50 million years vs. 50 years - a million-fold difference in the number of generations. In "a few decades", you'd get what, 2 generations of elephants.
Of course, most creationists don't think about things like that, so your book would probably sell quite well.
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"Illuminant light,
illuminate me."