GC ages and virial mass evolution of the modeled NGC 3115-analog galaxy compared to the observed GC ages in NGC 3115. Top and middle: age distributions of the GC population in NGC 3115 from Usher et al. (2019), with a sample of 116 GCs, and of the modeled GC population in an NGC 3115-analog galaxy from Valenzuela et al. (2021) with 525 GCs. The smooth distributions are smoothed using an assumed uncertainty of 1.5 Gyr for the GC ages. These are computed through a summation over normal distributions with the respective ages as the means and their uncertainties as the standard deviations. Bottom: dark matter virial mass evolution of the simulated NGC 3115-analog galaxy, showing its accretion history.