Proposed evolution of jaws in Namanereidinae. A Jaws with fully dentate cutting edge, layer almost inconspicuous in basal teeth B Layer increases their extension among basal teeth and reaches medial ones C Layer covers completely basal and medial teeth, and reaches subterminal ones D Teeth recede and become narrow, layer covers subterminal teeth excepting the last two E Just remnants of teeth are visible if any, layer increases its extension F Teeth fully replaced by the layer. Stages B and C in most Namalycastis species and Namanereis with serrated cutting edge; stage D as in Namanereis stocki and N. tiriteae; stage E as in Namanereis socotrensis; stage F as in Namanereis with bifid jaws and Namalycastis occulta.