  Let M_{g,n}^rt be the moduli space of stable n-pointed curves of genus g>1
with rational tails. We also consider the space C_g^n classifying smooth curves
of genus g with not necessarily distinct n ordered points. There is a natural
proper map from M_{g,n}^rt to C_g^n which contracts all rational components.
Tautological classes on these spaces are natural algebraic cycles reflecting
the geometry of curves. In this short note we study the connection between
tautological classes on M_{g,n}^rt and C_g^n. We show that there is a natural
filtration on the tautological ring of M_{g,n}^rt consisting of g-2+n steps. A
conjectural dictionary between tautological relations on M_{g,n}^rt and C_g^n
is presented. Our conjecture predicts that the space of relations in
R^*(M_{g,n}^rt) is generated by relations in R^*(C_g^n) together with a class
of relations obtained from the geometry of blow-ups. This conjecture is
equivalent to the the independence of certain tautological classes in Chow. We
prove the analogue version of our conjecture for the Gorenstein quotients of
tautological rings.

Algebraic Geometry