Proper semimajor axis a_p vs. the proper eccentricity e_p for the synthetic family (left column). It is an output of the N-body simulation, which initially included 660 bodies (i.e., 10 times more than observed) and later rescaled to the same size-frequency distribution as the observed one; a random background population was also included (middle column). Colors correspond the numbers of bodies N_box in the respective boxes. Finally, there is the observed family, and the corresponding χ² metric (right column). The “initial” conditions are shown at t = 0 Myr (top row), the best fit at 30 Myr (middle row), and a very poor fitat 520 Myr (bottom row) for comparison. Dotted lines on the χ²(t) plot correspond to the 1-σ and 3-σ levels. A reasonable match is only possible for young ages t ≲ 100 Myr.