s  = 2; pr  =  6;

Do[F[x_, 
          y_]  = (( (E^(-((((x^2)  +  (y^2)))/(4  t)) )))/(4  π t)) ; 
      Plot3D[F[x, y], {x, -s, s}, {y, -s, s}, Boxed -> False, 
        Axes -> False, PlotPoints  -> 100 {1, 1}, 
        PlotRange  ->  {0, pr}, Mesh  ->  False, 
        ViewPoint -> {1.3, -2.4, 
            1}], {t,  .005,  .15,  .005}]