Flattened galactic haloes and baryonic dark matter

We discuss the tight interconnection between microlensing optical depths, f lattening of dark haloes and low-to-intermediate redshift baryonic census. By analysing plots of the microlensing optical depth as a function of Galac tic coordinates for different values of axis ratio q of the Galactic MACHO halo, we have shown that observations are best described by a flattened hal o with q similar or equal to 0.6. There is no dynamical obstacle for such a choice of global halo shape. Both extremely flattened q similar or equal t o 0.2 and spherical q similar or equal to 1 haloes have several difficultie s, although not of equal severity. Consequences of such flattening for the cosmological density fraction contained in MACHOs are considered, and compa rison with mass in low- and intermediate-redshift Ly alpha forest and other plausible reservoirs of gas is discussed in context of a unified descripti on of the evolution of baryonic content of the Universe.