Best-fitting models for ZF-UDS-7329. The top panel shows the original PRISM spectra in black and the two best-fit models from pPXF. In blue is the Milky Way-like Kroupa set of SSPs and in orange is the bottom-heavy IMF Γ_b = 3.0 (this colour scheme is throughout the Letter). The middle panel shows the residuals between the models and observations, where the shaded region is the sodium doublet mask. The bottom panels show the mass fractions as a function of age.