  Understanding the physical formation of the Hubble sequence remains one of
the most important unsolved astrophysical problems. Searches for proto-disks
and proto-ellipticals can now be effectively done using deep wide-field Hubble
Space Telescope images taken with the new Advanced Camera for Surveys. Through
an analysis of concentrations (C), asymmetries (A) and clumpiness values (S)
(CAS) of galaxies found in the GOODS Field South, we are able to identify
objects possibly forming onto the Hubble sequence. Using this approach, we
detect a sizeable population of star forming luminous diffuse objects and star
forming luminous asymmetric objects between redshifts 0.5 < z < 2. These
galaxies have extremely low light concentrations, or high asymmetries, with
absolute magnitudes M_B < -19. The luminous diffuse objects are found in
abundance between z = 1 - 2, with fewer objects at z > 2 and z < 1. The
luminous asymmetric objects are found at a similar abundance, with a peak at
z~1. We argue that these galaxies are a subset of modern disks and ellipticals
in formation. The co-moving volume density of the luminous diffuse objects
between z = 1 - 2 is similar to the local density of bright disk galaxies, with
values ~5*10^{5} Gpc^{-3}. The SEDs of these objects are mostly consistent with
starbursts, or star-forming normal galaxies, with average uncorrected for
extinction star formation rates of ~4 M_0 yr^{-1}. These galaxies also host
35-40% of the star formation activity at 1 < z < 2. We briefly discuss the
implications of these objects for understanding the origin of the Hubble
sequence.
