Ages and metallicities of both cEs compared with a sample of cEs and massive compact galaxies from the literature. Left panel: Metallicity as a function of M_⋆ in units of 10⁹ M_⊙, with FS90 110 and FS90 192 identified by a diamond and a pentagon, respectively. The sample from the literature follows the same symbol coding as in previous figures, where framed symbols depict cEs with mean ages above 10 Gyr. The solid line shows the mass–metallicity relation for massive ETGs (McDermid et al. 2015), with dotted ones representing its dispersion. The dashed line corresponds to the relation fitted by Romero-Gómez et al. (2023) to ETGs from the Fornax cluster. Right panel: Age-metallicity distribution for the same sample of galaxies, with FS90 110 and FS90 192 highlighted, as in previous figures.