Yochelcionelloidea

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Yochelcionelloidea is an extinct superfamily of early molluscs from the Paleozoic era. Scientists aren’t sure exactly where they fit on the mollusc family tree, so they are thought to be either early gastropods (snails) or primitive monoplacophorans (shelled molluscs). They lived from the Lower Cambrian to the mid Cambrian period. The earliest members appear in the Middle Tommotian, and the group is most diverse from the Botomian to the early Middle Cambrian. The group was named by Runnegar and Jell in 1976. In some classifications they are placed within Gastropoda, but others place them in the class Helcionelloida (as Archaeobranchia, Helcionelliformes).