Biomechanical methods reveal construction principles in natural structures. To understand the process of shaping in the skeleton of vertebrates we assume that mechanical constraints are one of the most important factors. We begin by testing this hypothesis with simple models, which are analyzed using the Finite-Element- Method (FEM) with only minor basic rules for support and force initiation. The aim of this study of the crocodile-like fossil Proterosuchus is to obtain a simplified model, which is, in shape and internal structure, as close as possible to the natural counterpart. Our results of the virtual 2D- and 3D-model allow us to predict the origin of natural structures. This leads to a possible reconstruction of the soft tissues in the skull of Proterosuchus.