  Based on the boson realization of the Euclidean algebras, it is shown that
the five-dimensional Euclidean dynamical symmetry may emerge at the triple
point of the shape phase diagram of the interacting boson model, which thus
offers a symmetry-based understanding of this isolated point. It is further
shown that the low-lying dynamics in $^{108}$Pd, $^{134}$Ba, $^{64}$Zn, and
$^{114}$Cd may be dominated by the Euclidean dynamical symmetry.
