In-place operculum demonstrates that the Middle Cambrian <i>Protowenella</i> is a hyolith and not a mollusc

Protowenella is an early–middle Cambrian, isostrophically coiled, calcareous microfossil originally described from the middle Cambrian (Miaolingian) of Australia; it has been referred previously to molluscan classes Monoplacophora, Helcionelloida or Gastropoda. A unique specimen Henson Gletscher Formation (Miaolingian Series, Wuliuan Stage) North Greenland a bilaterally symmetrical operculum preserved in place within shell aperture. Paired cardinal processes and clavicles on inner side indicate that was hyolith morphologically close orthothecid Conotheca. transferred Mollusca Hyolitha, Order Orthothecida, Family Protowenellidae nov., representing novel morphological departure generally slender cones other hyoliths.John S. Peel [[email protected]], Department Earth Sciences (Palaeobiology), Uppsala University, Villavägen 16, SE-75236, Uppsala, Sweden.