Muscle scars of the Cambrian univalved mollusks and their significance for systematics

Zones of the honeycomb microsculpture have been discovered on the surface-of internal moulds of the Cambrian mollusks, i.e., Bemella communis, B. incomparabilis, Anhuiconus micromberus and Beshtashella tortilis from the Botomian Stage of South Australia and Bemella sp. and Oelandiella sp. from the Tommotian Stage of the Siberian Platform. The species represent three families of the Cambrian univalved mollusks: Helcionellidae, Corcospiridae, and Onychochylidae. It is supposed that these zones are the muscle attachment areas, i.e., muscle scars. The significance of this find for the systematics of the Cambrian mollusks is discussed.