  We consider a class of degenerate equations satisfying a parabolic
H\"ormander condition, with coefficients that are measurable in time and
H\"older continuous in the space variables. By utilizing a generalized notion
of strong solution, we establish the existence of a fundamental solution and
its optimal H\"older regularity, as well as Gaussian estimates. These results
are key to study the backward Kolmogorov equations associated to a class of
Langevin-type diffusions.
