The correlations between spectral indices and SFH parameters. The spectrum of LEGA-C 144377 does not cover the D _n 4000 region. D _n 4000 serves as a good qualitative proxy to the lookback time of the burst and the time that a galaxy became quiescent. On the other hand, there is no clear correlation between the burst strength and either D _n 4000 or EW(Hδ). LEGA-C 144377 has not become quiescent (see the main text), we manually put it at t _q = − 0.1.