Which came first, clusters or early-type galaxies? Insights from SpARCS and GOGREEN

At high and intermediate stellar masses, elliptical and lenticular galaxies have been associated with galaxy clusters and rich groups for more than half the history of the Universe.  But when and how did this association begin?  Were massive early-type galaxies already fully transformed  and without star formation when the clusters they are found in formed?  Were self-quenching and environmental effects always as distinct and separable as low-redshift studies suggest?  The SpARCS and GOGREEN surveys have been examining galaxy evolution in the densest environments at high-intermediate redshifts (0.8 < z < 2) in search of answers to these questions.  Our results over the last several years at redshifts 1 to 1.7 in particular suggest that environmental quenching takes time to establish itself after the early formation of galaxy clusters, and that environmental effects may not be clearly separable from galaxy-mass-related self-transformation when the star formation-density and morphology-density relations were first being established.