  The dynamical evolution of the recently detected stellar group Mamajek 2 is
studied by means of its past 3D orbit. The past orbits of the open clusters NGC
2516 and $\alpha$ Persei, belonging to the so-called "Local Association", were
also computed in order to check for a possible common past dynamical evolution
of these systems. To complete the data of the Mamajek 2 small group, we have
obtained high resolution FEROS spectra to measure the radial and also the
projected rotational velocities of its members; an estimate of its metallicity
was obtained as well. Two exceptionally low rotating A-type stars turned out to
be a strong magnetic Ap star in one case, and a normal A0 star with near-solar
metallicity in the other. The dynamical results showed that NGC 2516 and
Mamajek 2 may have had a common origin at the age of 135 $\pm$ 5 Myr. This
dynamical age confirms the individual ages of 140 Myr for NGC 2516 and 120
$\pm$ 25 Myr for Mamajek 2 obtained independently by photometric methods. Both
these groups appear to have the same solar metallicity giving support to a
common birth scenario. The dynamical approach is showing that some bound open
clusters can form in a coeval fashion with unbound stellar groups or with
associations.
