  We investigate the nature of Lyman break galaxies (LBGs) using a
chemodynamical model for evolution of galaxies. Our models predict an early
(the first Gyr) stage of intense star formation in the evolution of massive
spheroids which could be identified to the LBGs, observed at redshift $\sim 3$
with strong ongoing star formation. In particular, we are successful in
reproducing the properties of the LBG DSF 2237+116 C2 with a model describing a
young $\sim L^*$ spheroid. The comparison of the predictions of our models with
the observations gives support to the scenario in which LBGs are the
progenitors of present-day massive spheroids, i.e. bulges of luminous early
type spirals or luminous elliptical galaxies.
