US STOCKS-Wall St slumps on Greece uncertainties

* Greek official denounces bailout deal * McDonald's falls after April sales report * Fossil tumbles in biggest drop since 1995 * Indexes off: Dow 0.8 pct, S&P 0.9 pct, Nasdaq 1.1 pct By Ryan Vlastelica NEW YORK, May 8 (Reuters) - U.S. stocks fell on Tuesday as Greece's bailout pledge came into question, adding to worries France and Germany may split on how to tackle the region's debt crisis. The early losses mirrored trading in Europe, where the FTSEurofirst dropped