  The ages of stellar populations in 52 elliptical and S0 galaxies in the Coma
cluster are investigated using a new spectroscopic sample. More than 40% of the
S0s are found to have experienced recent star formation in their central
regions during the last ~5 Gyrs, while such activity is absent in the
ellipticals. Galaxies in this sample have absolute magnitudes in the range
-20.5 < M_B < -17.5, and the fraction of S0 galaxies with recent star formation
is higher at fainter luminosities. The observed luminosity range of S0 galaxies
with signs of recent star formation activity is consistent with them being the
descendants of typical star-forming spirals at intermediate redshift whose star
formation has been halted as a consequence of the dense environment.
