Dynamical Mass Determinations and Scaling Relations of Early-Type
  Galaxies
  I review our understanding of classic dynamical scaling relations, relating
luminosity, size and kinematics of early-type galaxies. Using unbiased
determinations of galaxy mass profiles from stellar dynamical models, a simple
picture has emerged in which scaling relations are driven by virial
equilibrium, accompanied by a trend in the stellar mass-to-light ratio (M/L).
This picture confirms the earliest insights. The trend is mainly due to the
combined variation of age, metallicity and the stellar initial mass function
(IMF). The systematic variations best correlate with the galaxy velocity
dispersion, which traces the bulge mass fraction. This indicates a link between
bulge growth and quenching of star formation. Dark matter is unimportant within
the half-light radius, where the total mass profile is close to isothermal
($\rho\propto r^{-2}$).
