  We have developed an efficient photometric technique for identifying young
early-type galaxy candidates using a combination of photometric redshifts,
spectral-type classification, and optical/near-infrared colors. Applying our
technique to the GOODS HST/ACS and VLT/ISAAC data we have selected a complete
and homogeneous sample of young elliptical candidates among early-type field
galaxies. The distribution of structural parameters for these candidates shows
that their selection, which is based on early spectral types, is fully
consistent with early morphological types. We investigate the evolution of
their luminosities and colors as a function of redshift and galaxy mass and
find evidence for an increasing starburst mass fraction in these young
early-type galaxy candidates at higher redshifts, which we interpret in terms
of massive field galaxies experiencing more massive/intense starbursts at
higher redshifts. Moreover, we find indications for a systematically larger
young elliptical fraction among sub-L*/2 early-type galaxies compared to their
brighter counterparts. The total fraction among the field early-type galaxies
increases with redshift, irrespective of galaxy luminosity. Our results are
most consistent with galaxy formation scenarios in which stars in massive
early-type field galaxies are assembled earlier than in their low-mass
counterparts.
