  The transition quadrupole moments, $Q_{\rm t}$, of four weakly populated
collective bands up to spin $\sim$ $65\hbar$ in $^{157,158}$Er have been
measured to be ${\sim}11 {\rm eb}$ demonstrating that these sequences are
associated with large deformations. However, the data are inconsistent with
calculated values from cranked Nilsson-Strutinsky calculations that predict the
lowest energy triaxial shape to be associated with rotation about the short
principal axis. The data appear to favor either a stable triaxial shape
rotating about the intermediate axis or, alternatively, a triaxial shape with
larger deformation rotating about the short axis. These new results challenge
the present understanding of triaxiality in nuclei.
