  We present results from our VLT Large Program to study the dynamical
evolution of Ultraluminous Infrared Galaxies (ULIRGs). We have so far obtained
near-infrared high-resolution ISAAC spectra of 53 local ULIRGs at several
merger timescales and 12 Palomar-Green QSOs (more than half of which are
IR-bright sources). We have extracted the stellar velocity dispersion and
rotational velocity along our slits to derive the kinematics of the merging
galaxies. These quantities enable us to answer the following questions about
the evolution of ULIRGs: 1) What are the progenitor mass ratios?, 2) How do the
stellar kinematics evolve?, and, 3) Is there a connection between ULIRGs and
QSOs? We find that the Ultraluminous phase is mainly triggered by mergers of
approximately equal mass galaxies, however, less violent minor mergers (of
progenitor mass ratio ~3:1) also exist in our sample. Dynamical heating of the
merging hosts is observed as the stellar systematic rotation decreases with
time in favour of the increase of random motions. The merger remnants, being
dispersion-dominated systems with non-negligible rotation, resemble elliptical
galaxies. Placing ULIRGs on the fundamental plane of early-type galaxies shows
that they resemble intermediate-mass ellipticals. After the nuclear
coalescence, the black hole masses of ULIRGs, calculated from their relation to
the host dispersions, are of the order 10^7-10^8 M_sun. To investigate whether
ULIRGs go through a QSO phase during their evolution, we perform a similar
(preliminary) analysis of the IR-bright-QSO kinematics. We find that the
average dispersion of the IR-bright QSOs is similar to that of the ULIRG
remnants, indicating that evolutionary links between the two populations may
exist.
