  In a Palatini $f(\mathcal{R})$-model, we define chonodynamical effects due to
the choice of atomic clocks as standard reference clocks and we develop a
formalism able to quantitatively separate them from the usual effective dark
sources one has in extended theories. We apply the formalism to Hubble drift
and briefly discuss the issue about the physical frame. In particular, we argue
that there is no physical frame in the sense one does different things in
different frames and that, in a sense, is the physical characteristic of
extended gravity. As an example, we discuss how Jordan frame may be well suited
to discuss cosmology, though it fails within the solar system.
