2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/124500We consider the case of $R^n$-gravity and perform a detailed analysis of the dynamics in Bianchi I cosmologies which exhibit {\it local rotational symmetry} (LRS). We find exact solutions and study their behaviour and stability in terms of the values of the parameter $n$. In particular, we found a set of cosmic histories in which the universe is initially isotropic, then develops shear anisotropies which approaches a constant value.4 pages, 2 figures; to appear in the proceedings of the MG11General Relativity and Quantum Cosmologytext