  We perform a molecular dynamical study of the isolated $d=1$ classical
Hamiltonian ${\cal H} = {1/2} \sum_{i=1}^N L_i^2 + \sum_{i \ne j}
\frac{1-cos(\theta_i-\theta_j)}{r_{ij}^\alpha} ;(\alpha \ge 0)$, known to
exhibit a second order phase transition, being disordered for $u \equiv
U/N{\tilde N} \ge u_c(\alpha,d)$ and ordered otherwise ($U\equiv$ total energy
and ${\tilde N} \equiv \frac{N^{1-\alpha/d}-\alpha/d}{1-\alpha/d}$). We focus
on the nonextensive case $\alpha/d \le 1$ and observe that, for $u<u_c$, a
basin of attraction exists for the initial conditions for which the system
quickly relaxes onto a longstanding metastable state (whose duration presumably
diverges with $N$ like ${\tilde N}$) which eventually crosses over to the
microcanonical Boltzmann-Gibbs stable state. The temperature associated with
the (scaled) average kinetic energy per particle is lower in the metastable
state than in the stable one. It is exhibited for the first time that the
appropriately scaled maximal Lyapunov exponent
$\lambda_{u<u_c}^{max}(metastable) \propto N^{-\kappa_{metastable}} ;(N \to
\infty)$, where, for all values of $\alpha/d$, $\kappa_{metastable}$
numerically coincides with {\it one third} of its value for $u>u_c$, hence
decreases from 1/9 to zero when $\alpha/d$ increases from zero to unity,
remaining zero thereafter. This new and simple {\it connection between
anomalies above and below the critical point} reinforces the nonextensive
universality scenario.
