Will mutations become less freqent?

My understanding is that the mutation rate has evolved (see Darwin in the Genome by Lynn Caporale).I beleive that Caporals is correct. As the mutation rate decreases, so does the fitness advantage of further "improvements" in copying fidelity. At some point we hit the situation where the mutatiion spreads so slowly that environmental changes will arrive before it becomes fixed in the population.It isn't a plausible explanation for the dinosaur extinction because that would require many different species to suffer the same effect, independantly.r

I have heard of convergent evolution. And the idea that all the dinosaurian species (except birds) not to mention the marine reptiles (e.g. icthyosaurs and plesiosaurs) would all converge in that way is not plausible. You really need to consier the diversity of the dinosaurs and other victims of the K/T mass extinction before you make speculations on the cause.