Time evolution of the surface density of solids for small planetesimals in a disk with power index p = 2. Thin lines correspond to the isolated formation of Jupiter, thick lines correspond to the simultaneous formation of the giant planets. Evidently, the presence of Saturn significantly reduces the surface density of solids at Jupiter’s location by the accretion of small planetesimals. The presence of Saturn delayed the formation time of Jupiter by a factor  ~ 2 (color figure only available in the electronic version).