The standard cosmological model successfully reproduces the properties
of the universe on supergalactic scales. However, it is unclear
whether it can match the detailed properties of galaxies themselves.
In particular, the origin of spheroidal galaxies is currently a point
of discord between observation and the standard hierarchical
model. For example, the stellar populations properties and sizes of
massive galaxies are difficult to reproduce by models.  Surprisingly,
in the past decade it has become clear that supermassive black holes
might be an essential ingredient to solve this puzzle: they are found
ubiquitously at the center of spheroidal galaxies and their mass
correlates with global properties of the host. Furthermore my work,
and that of others, has shown that global properties of spheroidal
galaxies also correlate very tightly with those of their dark matter
halos.  A unified description of dark matter, baryons and black holes
seems thus necessary to explain the observed correlations, and could
perhaps reconcile the standard model with the conflicting
observations. I will present highlights of my observational research
program aimed at measuring the evolution over cosmic time of black
holes, stars, and dark matter in spheroidal galaxies.