... Panoramic spectroscopy of the sample of 80 nearby lenticular galaxies is presented. ... By comparing the subsample of the S0s with the chemically distinct nuclei to the total sample of nearby S0s (Fig. 1), we have assured that the chemically distinct nuclei are always younger than the surrounding bulges: the mean age difference between the chemically distinct nuclei and their surrounding bulges is 2.8 Gyr while the age difference between the nuclei and the bulges for the whole sample is only 1 Gyr. ...