The temperature and magnetic field dependence of ultrafast photoinduced spin and quasiparticle relaxation dynamics is reported in La0.67Ca0.33MnO3 and LaMnO3 single crystals and thin films. Both manganites reveal an unusually slow (similar to10 mus) carrier relaxation process attributed to the spin-lattice relaxation in localized states. The quasiparticle dynamics is governed by the temperature- and magnetic field-dependent pseudogap in La0.67Ca0.33MnO3, and by the temperature-independent Jahn-Teller gap in LaMnO3. The loss of spectral weight near the Fermi level in La0.67Ca0.33MnO3 strongy affects the quasiparticle relaxation dynamics as temperature increases from below T-C. Our results show that the coupled dynamics of charge, spin and lattice is strongly correlated with the distinct gap structures in these manganites. (C) 2004 American Institute of Physics.