  Detailed measurements of the azimuthal anisotropy (\v2) for identified
charged particles are reported as a function of transverse momentum ($p_T$) and
centrality for Au+Au collisions at \sqrtsNN = 200 GeV. The measurements
indicate clear evidence for eccentricity and particle flavor scaling over a
broad range of centralities and transverse rapidity $y_T$, indicating a
hydrodynamical origin of the fine structure of azimuthal anisotropy at RHIC.
The observed scaling supports the picture of a suddenly hadronizing
(recombining) fluid of quarks. An apparent breaking of flavor scaling at
relatively large values of $y_T$ points to an important change in the mechanism
for particle emission.
