  We present a surprising redefinition of matrix fermions which brings the
supercharges of the $\cal N$-extended supersymmetric $A_{n-1}$ Calogero model
introduced in [1] to the standard form maximally cubic in the fermions. The
complexity of the model is transferred to a non-canonical and nonlinear
conjugation property of the fermions. Employing the new cubic supercharges, we
apply a supersymmetric generalization of a "folding" procedure for
$A_{2n-1}\oplus A_1$ to explicitly construct the supercharges and Hamiltonian
for arbitrary even-$\cal N$ supersymmetric extensions of the $B_n$, $C_n$ and
$D_n$ rational Calogero models. We demonstrate that all considered models
possess a dynamical $osp({\cal N}|2)$ superconformal symmetry.
