Dynamical simulation of orientation texture evolution of a polymeric liquid crystal under simple shear flow has been carried out. The Leslie-Ericksen equation was numerically solved to obtain three dimensional orientation over the shear plane spanned by the flow (x) and thickenss (y) axes. The present study shows a cascade of complex orientation texture evolutions as a function of the Ericksen number (E) during shear flow starting from a near perfect monodomain condition. When E-2>E >E-1, directors in the middle gap region twist out of the shear plane in a uniform sense. When E-3>E >E-2, the twist sense is not of the same sign, but alternating along the now axis. When E-4>E >E-3, the middle orientation wall of the alternating twist sense divides into a pair, which migrate towards the bounding plates, forming a series of tubular orientation walls. When E >E-4. the tubular orientation walls still form, but through a reentrant two-dimensional in-shear-plane state.