In a recent paper "The evolution of popular music: USA 1960–2010" published on the Royal Society Open Science website, the authors claim that "... these results suggest that, even if the British did not initiate the American revolution of 1964, they did exploit it and, to the degree that they were imitated by other artists, fanned its flames ...".
So, my question is: If you agree with the authors that there was already a music revolution "brewing" in the US in 1964, who were these revolutionaries? Sure, we already had Elvis, Bill Haley, Carl Perkins, Little Richard, etc. So we had Rockabilly and later Rock & Roll. But was there a US band with a "new" sound and a tune like "I Want To Hold Your Hand" (and a whole bunch more where it came from) poised to become the phenom that the Beatles were?