The possibility of cooperative dynamical Jahn-Teller (JT) in rhombohedral LaMnO3 is considered. For the verification of such an assumption, lattice structure and dynamic calculation are performed. The calculation is performed in the framework of pair interionic potentials and shell model explicitly allowing for the JT term in crystal energy and dynamical matrix. Using such an assumption, the structural phase transition from monoclinic to rhombohedral phase is considered. The appearance of a broad high frequency line near 640 cm-1 in Raman scattering spectra of rhombohedral LaMnO3 is explained. The appearance of ferromagnetism in the rhombohedral phase, which is only due to superexchange interaction is shown.