Molecular simulation results are reported for the liquid-crystal phase transitions of both monomers and dimers of hard prolate ellipsoids. The effect of different elongations (gamma) is studied. In contrast to earlier work, evidence is found for the onset of isotropic-ordered phase transitions for monomers of relatively small elongations, although the transition is not stable. Dimers of prolate hard ellipsoids behave very differently to ellipsoid monomer of equal size. In the dimer case, a clear isotropic-ordered phase transition is observed whereas such a clear transition is absent in monomers.