  We infer the crater chronologies of Ceres and Vesta from a self-consistent
dynamical model of asteroid impactors. The model accounts for planetary
migration/instability early in the solar system history and tracks asteroid
orbits over 4.56 Gy. It is calibrated on the current population of the asteroid
belt. The model provides the number of asteroid impacts on different worlds at
any time throughout the solar system history. We combine the results with an
impactor-crater scaling relationship to determine the crater distribution of
Ceres and Vesta and compare these theoretical predictions with observations. We
find that: (i) The Ceres and Vesta chronologies are similar, whereas they
significantly differ from the lunar chronology. Therefore, using the lunar
chronology for main belt asteroids, as often done in previous publications, is
incorrect. (ii) The model results match the number and size distribution of
large (diameter $>90$ km) craters observed on Vesta, but overestimate the
number of large craters on Ceres. This implies that large crater erasure is
required for Ceres. (iii) In a model where planetary migration/instability
happens early, the probability to form the Rheasilvia basin on Vesta during the
last 1 Gy is 10\%, a factor of $\sim1.5$ higher than for the late instability
case and $\sim2.5$ times higher than found in previous studies. Thus, while the
formation of the Rheasilvia at $\sim1$ Gy ago (Ga) would be somewhat unusual,
it cannot be ruled out at more than $\simeq1.5\sigma$. In broader context, our
work provides a self-consistent framework for modeling asteroid crater records.
