- Galaxies in galaxy clusters have lower orbital anisotropy at high redshift compared to the present day. - Blue, star-forming galaxies that entered clusters recently have lower anisotropy than galaxies that have been cluster members for longer. - Simulations show that the orbital anisotropy of cluster member galaxies increases over time as galaxies move in the deepening cluster potential well. - The increasing mass concentration of clusters causes galaxy orbits to become more radially anisotropic.