English: Fig. 10 Reconstruction of the topological arrangement in the functional head region of A. symbrachiata. The reconstruction of the mouth follows that of other radiodontans, such as Hurdia and Peytoia, although the symmetry and the arrangement of mouth plates are conjectural. The relative position of the GLSs is based on their association with the reduced transitional flaps and inferred function (by comparison with gnathobases of euarthropods, see the main text). The correspondence between GLSs and the reduced transitional flaps is indicated by the coloured outline. The relative size of each component is based on specimens illustrated herein. The size of animal is not scaled. See Methods for abbreviations