First occurrence of a new Ocruranus-like helcionelloid mollusc from the lower Cambrian of East Gondwana

A new cap-shaped mollusc, Emargimantus angulatus gen. et sp. nov. is described from the Arrowie Basin of South Australia. The new species is closely comparable to mollusc species from South China and North-East Greenland previously described under the generic name Ocruranus Liu, a genus recently reinterpreted as a multiplated, possibly polyplacophoran mollusc. Emargimantus is interpreted as a univalved helcionelloid mollusc and differs from Ocruranus in both morphology and function. E. angulatus represents the first discovery of Ocruranus-like helcionelloids in the lower Cambrian of eastern Gondwana and demonstrates that these molluscs had a global distribution during the early Cambrian.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A new species from the lower Cambrian succession of South Australia is included in a new genus — Emargimantus. ► Univalved helcionelloid mollusc is quite distinct from the polyplacophoran Ocruranus. ► First find of this type of mollusc from lower Cambrian strata of Gondwana.