  The Kepler mission results indicate that systems of tightly-packed inner
planets (STIPs) are present around of order 5% of FGK field stars (whose median
age is ~5 Gyr). We propose that STIPs initially surrounded nearly all such
stars and those observed are the final survivors of a process in which
long-term metastability eventually ceases and the systems proceed to
collisional consolidation or destruction, losing roughly equal fractions of
systems every decade in time. In this context, we also propose that our Solar
System initially contained additional large planets interior to the current
orbit of Venus, which survived in a metastable dynamical configuration for
1-10% of the Solar System's age. Long-term gravitational perturbations caused
the system to orbit cross, leading to a cataclysmic event which left Mercury as
the sole surviving relic.
