Understanding the formation and the evolution of early-type galaxies (ETGs) is one of the priorities of the observational cosmology since they contain most (~70%) of the present-day stars and baryons. Recent observations have shown that in spite of the majority of ETGs lies on well defined scaling relations up to z~1.5-2, a significant fraction of them deviate appearing significantly smaller in spite of the same mass. This evident non homogeneity of ETGs has to originate at an earlier epoch (z>2), in the preceeding 3 Gyr, when they have been assembled. The relevant question is then: which formation scenario and early physical conditions can account for the observed different properties of ETGs yet observed at z~2 ? We combined proprietary and archival HST observations to collect a sample of ~60 ETGs at 1