Time evolution of β(r), defined by Eq. (1), in the underfilling models. The top row shows β calculated from the velocity dispersion of all stars in the SC (regardless of mass), and the rows below are calculated for specific mass groups – from the least massive in the second row, intermediate-mass in row three, and the most massive stars in the bottom row (see also the labels on the right-hand side). Red colours correspond to radial anisotropy, and blue colours to tangential anisotropy. If the fit is poorly defined because of an insufficient number of data points in a radius–mass bin, we mask the corresponding pixel in grey. To give a sense of the radial scale and dynamical evolution of the SCs in each plot, we also show the 1% L.r., the half-mass radius, the 99% L.r., and the tidal radius (from bottom to top; black lines). We note that because of the log-scale on the vertical axis, the bins below 2% may appear more prominent than the other bins despite covering a smaller radial range.