  We compare the predictions of the Pe\~narrubia et al. (2005) model for the
Monoceros stellar ring around the Milky Way with new observational constraints
that provide deeper insights on its origin. Recently, Grillmair (2006) found a
coherent sub-structure in a panoramic analysis of SDSS data, spanning 5x65
deg^2 above the Galactic plane towards the anticenter. We show here that this
structure strikingly matches the prior model predictions in projected position
on the sky and the distance (~10 kpc) to within 20%. Newly measured velocities
within this sub-structure also match the model predictions perfectly. This
match suggests that the model assumptions are correct, namely, that the
Monoceros Ring corresponds to a tidal stream wrapping the Milky Way that
results from a single disruption event of a satellite (M~5x10e8 M_sun) with a
prograde, low-inclination, low-eccentric orbit. Further support for the
external origin of the Mon Ring comes from new metalicity measurements of the
Mon Ring, which show that this system is much more metal poor than star
clusters in the outer Galactic disk at the same radius, and independent
detections of RRLyr over-densities in the area that are in excellent agreement
with the model predictions. That these observational data can be
comprehensively explained by alternative disk heating scenarios seems not
likely, but would need to be checked by detailed modeling.
