[Ca/Fe], [Mg/Fe] and [Ti/Fe] abundances for the Sculptor targets from this work versus their [Fe/H] (red asterisks). Overplotted are stars from other studies. Red symbols indicate Sculptor stars from Hill et al. (in prep.), Shetrone et al. (2003), Tafelmeyer et al. (2010) and Frebel et al. (2010a). The black small circles are the halo stars from the Cayrel et al. (2004) sample. A typical error bar for this sample is shown in the lower right corner of each panel. The Mg values are taken as updated by Bonifacio et al. (2009). A sample of very and extremely metal-poor stars from other galaxies are plotted as gray symbols. We show all literature values for stars in ultra-faint galaxies and stars with [Fe/H]  < −2.5 dex in the classical dwarf spheroidals. Frebel et al. (2010b) for Ursa Major II and Coma Berenices, Tafelmeyer et al. (2010) for Fornax, Tafelmeyer et al. (2010) and Aoki et al. (2009) for Sextans, Venn et al. (2012), and Lemasle et al. (2012), for Carina, Koch et al. (2008) for Hercules, Cohen & Huang (2009) and Fulbright et al. (2004) for Draco, Cohen & Huang (2010) for Ursa Minor and Norris et al. (2010b) for Bootes I. For Ti, Ti II abundances are used for the stars from this work, since these are determined with smaller errors generally. For most other works we adopt Ti II abundances as well, except for the Hercules stars and the Draco star from Fulbright et al. (2004) where only Ti I was available. For the Cayrel et al. (2004) sample, the average of Ti I and Ti II is shown. All [Fe/H] abundances are determined from Fe I lines, except again for Cayrel et al. (2004) stars for which we show an average value (generally the difference between their Fe I and Fe II abundances is very minimal).