  We compare elliptic flow evolution from ideal hydrodynamics and covariant
parton transport theory, and show that, for conditions expected at RHIC,
dissipation significantly reduces elliptic flow even for extreme parton cross
sections and/or densities sigma_gg * dN/d\eta(b=0) ~ 45 mb * 1000. The
difference between transport and hydrodynamic elliptic flow is established
rather early during the evolution of the system, but the buildup of elliptic
flow is surprisingly insensitive to the choice of the initial (formation or
thermalization) time in both models.
