Structure and Kinematics of Early-Type Galaxies from Integral-Field
  Spectroscopy
  Observations of galaxy isophotes, longs-slit kinematics and high-resolution
photometry suggested a possible dichotomy between two distinct classes of E
galaxies. But these methods are expensive for large galaxy samples. Instead,
integral-field spectroscopic can efficiently recognize the shape, dynamics and
stellar population of complete samples of early-type galaxies (ETGs). These
studies showed that the two main classes, the fast and slow rotators, can be
separated using stellar kinematics. We showed there is a dichotomy in the
dynamics of the two classes. The slow rotators are weakly triaxial and dominate
above $M_{\rm crit}\approx2\times10^{11} M_\odot$. Below $M_{\rm crit}$, the
structure of fast rotators parallels that of spiral galaxies. There is a smooth
sequence along which, the metals content, the enhancement in $\alpha$-elements,
and the "weight" of the stellar initial mass function, all increase with the
CENTRAL mass density slope, or bulge mass fraction, while the molecular gas
fraction correspondingly decreases. The properties of ETGs on galaxy scaling
relations, and in particular the $(M_{\ast}, R_{\rm e})$ diagram, and their
dependence on environment, indicate two main independent channels for galaxy
evolution. Fast rotators ETGs start as star forming disks and evolve trough a
channel dominated by gas accretion, bulge growth and quenching. While slow
rotators assemble near the center of massive halos via intense star formation
at high redshift, and remain as such for the rest of their evolution via a
channel dominated by gas poor mergers. This is consistent with independent
studies of the galaxies redshift evolution.
